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Tektronix 1480-SERIES User's Manual

1. Instrument fils standard 19 inch rack ORDERING INFORMATION 1480C NTSC Waveform Monilor 1480R NTSC Waveform Monitor 1481C PAL Waveform Monitor 1481R PAL Waveform Monitor 1482C PAL M Waveform Monitor 1482R PAL M Waveform Monitor 1485C PAL NTSC Dual Standard Wavelorm Monilor 1485R PAL NTSC Dual Standard Waveform Monitor Option 01 1 megohm 20 pf probe input probe not included Suggested Probe P6065A 10X Probe 6 ft Order 010 6065 13 9 ft Order 010 610505 Option 02 With carrying Case Cabinet Version Only Option 03 With Blank CRT Option 07 Slow Sweep Option 08 Adds capability of recognizing four field sequence of SECAM 1481C 1481R 1485C 1485R only TEKTRONIX Automatic Correction Products are also available for 525 60 NTSC systems Tektronix COMMITTED TO EXCELLENCE P O Box 500 Beaverton Oregon 97077 U S A 3 11 Application Notes 1480 Series SN B060000 up application notes Tektronix COMMITTED TO EXCELLENCE UU UU UU UU ea no 13 Time Base Fold Back A Novel Improvement Over Double Triggering for Video Testing By Charles W Rhodes In video testing one is often comparing the amplitude of a test signal with the reference level provided by still another test signal For example the measurement of pulse to bar ralio using the 2T sine squared pulse and the line bar or measuring chrominance to luminance gain equality with the modulated sine squared pulse and li
2. 2338 12 Fig 1 13 Magnified Sweep a X1 b X5 c X10 d X20 e X25 f X50 Unpacking and Incoming Inspection 1480 Series SN B060000 up b VARiable MAGNIFIER 1481 1482 amp 1485 only Set the MAGNIFIER TO X1 and the DISPLAY to 10 us DIV See Fig 1 14 Rotate the VARiable MAGNIFIER back and forth to check its total range Change in duration of one line from less than 1 2 scale line to greater than 1 2 scale line See Fig 1 14 This procedure has only covered the standard instru ment if the instrument being looked at contains any options it will be necessary to consult the Performance Verification Procedure Section 5 for familiarization REPACKAGING INSTRUCTIONS The 1480 Series shipping carton provides maximum instrument protection during shipment If reshipment becomes necessary repackaging the instrument in its original carton will minimize the danger of damage during shipment Figure 1 15 and 1 16 show how to repackage the instrument 1 10 2338 13 Fig 1 14 Variable Magnifier 1481 1482 1485 only a Greater than 1 b Less than 1 Unpacking and Incoming Inspection 1480 Series SN B060000 up Fig 1 15 1480 Series Rackmount packaging e 1 11 Unpacking and Incoming Inspection 1480 Series SN B060000 up Fig 1 16 1480 Series Cabinet model packaging 1 12 REV A SEP 1980 Section 2 1480 Series SN B060000 up OPERATING INSTRUCTIONS The 1480 Series of T
3. m 60 40 Fig 5 3 NTSC Color Bar Signal Color Bars are in identical location for PAL signal REV B FEB 1980 Performance Verification 1480 Series SN B060000 up Table 5 1A VOLTS Leveled FULL Sine wave SCALE Generator Amplitude Limit 0 5 50 kHz 1 volt Set as reference at 1 volt 0 5 5 MHz 1 volt 2 20 mV or 2 8 IRE Ref 50 kHz 0 5 8 MHz 1 volt 2 3 from 50 kHz reference Ref 50 kHz 0 5 10 MHz 1 volt 2 5 from 50 kHz reference Ref 50 kHz Table 5 1B VOLTS Leveled FULL Sine wave SCALE Generator Amplitude Limit L 0 2 50 kHz 1 volt Set as reference at 1 volt E 0 2 5 MHz 1 volt 2 20 mV or 2 8 IRE Ref 50 kHz 0 2 8 MHz 1 volt 2 3 Ref 50 kHz 0 2 10 MHz 1 volt 2 5 Ref 50 kHz k Return the leveled sine wave generator frequency to 50 kHz Change the 1480 Series VOLTS FULL SCALE selector to 1 0 and check for 1 volt of display amplitude Do not change the leveled sine wave generator amplitude for the remainder of this step Set the 1480 Series VOLTS FULL SCALE selector to 0 2 and vertically position the top of the display to the 1 0 V or 100 IRE line Note because the vertical sensitivity has been increased by a factor of five the graticule scale reduces by a factor of five Each major division is now 20 mV or 2 IRE instead of 100 mV or 10 IRE Minor divisions are now 2 mV or 0 4 IRE m Check auxi
4. K 4 is read as the greatest deviation of the baseline of the 2T pulse from flatness using the tolerance limit lines as reference e g if the distorted baseline just reached the limit lines at one or more points then the value of K would be 5 Other values can be obtained by interpolation or for appreciably smaller readings by increasing the vertical gain as described in Part 1 above giving the type of display shown in Figure 2b Figure 2a Measurement of K p Figure 2b As Figure 2a but VOLTS FULL SCALE set at 0 2 Part 3 optional measurement Bar Trail Smear Control Settings As immediately above In a linear system distortion at the lower video frequencies is measured by the value of K but in some instances a type of non linearity distortion may be present which gives rise to a slow decay of the lrailing edge of the bar not consistent with the distortion of the bar top A measure of the seriousness of this may be obtained immediately after the K reading by shift ing the trace horizontally until the mid point of the trailing edge of the bar coincides with the right hand member of the pair of circles beneath ihe K box Figure 3 The percentage bar trail can then be found from the point where this transition inter sects the small vertical scale located between points B and B3 Another form of this distorlion may cause an undershoot fol lowed by a slow rise to the final value This is read off in exa
5. VOLTS FULL SCALE 1 0 CAL RESPONSE FLAT DC RESTORER FAST SYNC TIP OPER and CAL buttons both depressed MAG OFF DISPLAY 5 us div FIELD 1 8 LINE SELECTOR 17 DIG SYNC INT DIRECT ALL FIELDS OFF The display obtained with these settings will probably seem confusing just at first glance so to make it clearer to under stand reduce the input temporarily to about 50 of the pre vious value when it will be evident that the display consists of the same ITS waveform repeated at lwo levels Figure 1 3 2 no 11 UUUUUU Figure 1 Normal display at reduced amplitude What in fact has happened is that a square wave whose period is 4H i e 4 times line duration and whose amplitude is exactly one volt has been linearly added to the test waveform A complete cycle of the square wave looks like the photograph Figure 2 with a pair of TV lines successively located at each of the two voltage levels but the synchronizing arrangements of the 1480 Series are such that the display always appears in the overlaid form Figure 2 Display locked to calibrating square wave Since the vertical separation of the two traces is as has been said exactly one volt it follows that when the sync bottom of the upper trace is located on precisely the same horizontal graticule line as the bar top of the lower trace then the overall amplitude of the video signal is also one volt This provides a very simple criterion for determinin
6. INPUT A to PIX MONITOR OUT 1 0 02 VARIABLE VOLTS FULL SCALE RANGE Input signals between 0 7 volts and 20 volts can be adjusted to 1 voll equivalent display height Maximum Input Signal lor inspecification op eration of AUX VIDEO OUT and PIX OUT AC CPL D INPUT A and B 20 V P P at any APL Display distortion 1 0 V P P al any APL if both AUX VIDEO OUT and PIX OUT are terminated for distortion free signal al those outputs DC CPL D INPUT A and B 15 V DC Peak AC AUX VIDEO IN 15 V DC Peak AC Maximum Output DC Voltage AUX VIDEO OUT and PIX MONITOR OUT into 75 9 0 5 V DC Common Mode Rejection Ratio A B 60 Hz gt 46 dB 15 kHz gt 46 dB 4 43 MHz gt 34 dB Frequency Response FLAT including INPUT A or INPUT B Through AUX VIDEO OUT or PIX MONITOR OUT from 50 kHz Reference 50 kHz to 5 MHz 0 5 5 MHz lo 10 MHz 05 3 IRE Conforms to IRE 1958 standard 238 1 Attenuation at 443 MHz 22 dB LOW PASS Attenuation gt 14 dB 500 kHz and above 3 58 MHz 1 of FLAT at 3 58 MHz 3 dB down al 3 1 to 3 4 MHz and 38 lo 40 MHz 4 43 MHz 1 of FLAT at 4 43 MHz 3 dB down at 3 9 lo 4 1 MHz and 4 7 lo 4 9 MHz DIFF D STEPS Per mits amplitude comparisons of risers on stair step signal with automatic gain increase of 5 limes attenuation 2 dB from 0 4 to 05 MHz atlenuation gt 20 dB at 15 kHz and 2 MHz al tenuation 40 dB at 3 58 MHz and 4 43 MHz Linear Waveform Distortion Pulse Preshool
7. Pulse Overshoot and Pulse Ringing 05 of applied pulse amplitude 25 ws Bar Till 05 Field Square Wave Tilt 1 Pulse to Bar Ratio 0 99 1 to 101 1 or 099 to 1011 Non Linear Waveform Distortion Differential Gain Displayed 05 at any APL AUX VIDEO OUT and PIX MONITOR OUT 025 at any APL Differential Phase AUX VIDEO OUT and PIX MONITOR OUT 025 at any APL DC RESTORER Mains Hum Attenuation Slow 10 Fast 26 dB Shift caused by Presence or Absence of Burst 1 IRE or 7 mV Return Loss Wilh 75 Termination INPUT A or B gt 40 dB DC to 5 MHz AUX VIDEO IN AUX Video OUT or PIX MONITOR OUT 34 dB DC to 5 MHz Vertical Overscan lor 1 V Peak to Peak Com posile Video Signal all specifications are valid at 10 05 and 02 volts FLLL SCALE and any vertical position setting to 5 MHz Calibrator Accuracy 1 V 02 714 mV and 700 mV 05 Timebase Accuracy and Linearity 5 s DIV and 10 4s DIV Accuracy Over Center 10 Div 1 Linearity Overall 1 Magnified Timing and Linearity For center 10 divisions of unmagnitied sweep 2 accu racy 2 linearity 2 FIELD Sweep Length and Linearity 12 7 div 05 div FIELD SELECTOR Posilive selection of ODD 2 amp 4 or EVEN 1 amp 3 in 525 60 Systems Display starts on selected field Positive selection of 1 2 3 or 4 or 1 amp 3 2 amp 4 in 625 50 Systems Display starts on selected field REV A SEP 1980 LINE SELECTOR VARIABLE
8. 1480 Series SN B060000 up d Check that the red bar is within 196 of the amplitude set earlier in this step The tops of the bars should be flat and rise and fall time of the color burst should be nearly identical e Disconnect the composite video signal and connect the leveled sine wave generator to the 1480 Series instru ment Set the leveled sine wave generator frequency to 3 58 MHz and amplitude for a convenient reference 100 IRE f Check that the display amplitude is 3 dB from the reference 100 IRE at 3 58 MHz at 3 1 to 3 4 MHz and 3 8 to 4 0 MHz 18 Check 4 43 MHz Bandpass Filter if used a Connect the video signal source to the VIDEO INPUT A connector and terminate the loop thru connec tor in 75 Q Setthe video signal source fora standard color bar test signal b Set the 1480 Series VOLTS FULL SCALE selector and the VOLTS FULL SCALE VAR so that the red bar is 700 mV in amplitude c Set the RESPONSE selector to 4 43 BANDPASS d Check that the red bar is within 1 of the amplitude set earlier in this step The tops of the bars should be flat and the rise and fall time of the color burst should be nearly identical e Disconnect the composite video signal and connect the leveled sine wave generator signal to the 1480 Series instrument f Set the leveled sine wave generator frequency for 4 43 MHz and amplitude for a convenient reference 1 Volt g Check that the display amplitude is 3 dB from th
9. 4nd Pass Amplitude within 1 of amplitude in Flat response position Bandpass approximately 600 kH 4 43 Band Pass Amplitude within 1 of amplitude in Flat response position Bandpass approximately 600 kHz IRE Conforms lo IRE Standard 238 1 1958 amended DC Restorer Keyed type may be turned off Clamping point BACK PORCH SYNC TIP TIME CONSTANT FAST reduces mains hum 226 dB SLOW reduces mains hum lt 1 dB Calibrator Amplitude selected by dc Restorer switch Syne Tip 1 volt 0 2 Back Porch 714mV or 700mV 0 5 Linear Waveform Distortion Pulse bar ratio 1 SHORT TIME preshoot overshoot ringing lt 0 5 on 100 ns sin pulse LINE TIME TILT or rounding 0 596 FIELD TIME AC coupled lt 1 Non Linear Distortion Differential gain lt 0 5 HORIZONTAL DEFLECTION Time Base 5 ysec and 10 usec Div 1 over center 10 divisions tusec 0 5 usec 0 25 usec 0 2 usec and 0 1 usec Div 2 over cenler 10 divisions 2 FIELD 12 7 division 1 External Sync Input Two loop through high impedance with gt 46 dB return loss in a 75 Q sys tem Inputs are slaved to A and B input or to A external sync input only External Sync Input Requirements 400 mV to 2 volls composite video or 200 mV to 8 volts com posite sync Field Selector Positive selection of Field 1 or 2 in the NTSC system Positive selection of 1 2 3 40r1 amp 3 2 amp 4 in the PAL systems e Selector Dig Selects lines 9
10. AUX VIDEO IN to INPUT A 1 5 0 3 dB GAIN INPUT A lo AUX VIDEO OUT 1 0005 INPUT A to PIX MONITOR OUT 1 0 02 VARIABLE VOLTS FULL SCALE RANGE Input signals between 0 7 volts and 2 0 volts can be adjusted to 1 volt equivalent display height Maximum Input Signal for inspecification op eralion of AUX VIDEO OUT and PIX OUT AC CPL D INPUT A and B 2 0 V P P at any APL Display distortion 10 V P P at any APL if both AUX VIDEO OUT and PIX QUT are terminated for distortion free signal at those outputs DC CPL D INPUT A and B 15 V DC Peak AC AUX VIDEO IN 1 5 V DC Peak AC Maximum Output DC Vollage AUX VIDEO OUT and PIX MONITOR OUT into 75 2 0 5 V DC Common Mode Rejection Ratio A B 60 Hz gt 46 dB 15 kHz gt 46 dB 4 43 MHz gt 34 dB Frequency Response FLAT including INPUT A or INPUT B Through AUX VIDEO OUT or PIX MONITOR OUT from 50 kHz Reference 50 kHz to 5 MHz 0 5 5 MHz lo 10 MHz 05 3 IRE Conforms to IRE 1958 standard 238 1 Attenuation al 4 43 MHz gt 22 dB LOW PASS Attenuation gt 14 dB 500 kHz and above 3 58 MHz 1 of FLAT al 3 58 MHz 3 dB down al 3 1 to 3 4 MHz and 38 to 4 0 MHz 4 43 MHz 1 of FLAT at 4 43 MHz 3 dB down at 3 9 to 4 1 MHz and 47 to 4 9 MHz DIFF D STEPS Per mils amplitude comparisons of risers on stair step signal wilh automatic gain increase of 5 limes attenuation lt 2 dB from 0 4 to 0 5 MHz atlenuation gt 20 dB al 15 kHz and 2 MHz
11. Characterislic Performance Requirement Supplemental Informalion Temperature Operating 0 C to 50 C Storage 40 C to 65 C Altitude Operating To 15 000 feet Storage To 50 000 feet 4 11 Specification 1480 Series SN B060000 up Table 4 9 MECHANICAL CHARACTERISTICS Characteristics English Units i Metric Units Cabinet Model Length 16 95 inches 43 cm Width 8 50 inches 21 6 cm Height 8 25 inches 21 cm Net Weight 21 Ib 8 oz 9 81 kg Domestic Shipping Weight 28 Ib 8 oz 12 9 kg Export Shipping Weight 41 Ib 8 oz 18 8 kg Rackmount Model Length 18 inches 45 7 cm Width 19 inches 48 3 cm Height 5 25 inches 13 3 cm Net Weight 24 Ib 9 oz 11 2 kg Domestic Shipping Weight 53 Ib 2 oz 24 1 kg Export Shipping Weight 75 lb 2 oz 34 1 kg 4 12 Section 5 1480 Series SN B060000 up PERFORMANCE VERIFICATION PROCEDURE This procedure verifies the Performance Requirements of the Electrical Characteristics found in Section 4 Steps at the end of the procedure are for the various operating options i e Option 1 X10 Probe these options may or may not be present in the instrument under test allows for a single verification procedure for all models If the operation of this instrument is found to beoutside the performance requirements it should be referred to a qualified service technician for re adjustment 1480 Series Waveform Monitors have two basic graticule s
12. Check AUX VIDEO OUT Response a Connect the video signal source composite video output through a 75 Q feed thru termination and the bnc cable tee connector to the A and B VIDEO INPUTS Do not terminate the inputs b Connect the AUX VIDEO OUT through the 1 5 dB attenuator to the AUX VIDEO IN connector c Set the video signal source for a color bar test signal output 5 6 d With the RESPONSE switch in the FLAT position generally note the amplitude of the chrominance portion of the display and specifically note the amplitude difference between the yellow and cyan bars note also the peak to peak amplitude of the composite signal e Set the RESPONSE switch to AUX VIDEO IN f Check the peak to peak display amplitude of the composite signal it should be within 5 of that noted previously g Check the chrominance amplitude and the amplitude difference between the yellow and cyan bars it should be within 0 5 of that noted previously 14 Check IRE Filter NTSC only a Connect an NTSC video signal source to the 1480 Series VIDEO INPUT A connector and terminate the loop thru connector in 75 Q b Set the RESPONSE switch to IRE and the INPUT Switch to A AC CPL D c Set the video signal source for a five step staircase modulated with 20 IRE of subcarrier step d Check that the luminance portions of the signals have no preshoot overshoot or ringing Chrominance on the staircase should be 2 9 IRE or less
13. OUTput Less than 0 25 any APL Differential phase AUXiliary VIDEO OUTput Less than 0 25 any APL Picture PIX MONITOR Less than 0 25 any APL Maximum Output DC Voltage AUXiliary VIDEO OUTput 0 5 V dc into 75 ohms Picture PIX MONITOR OUTput 0 5 V dc into 75 ohms Input signal absent and line strobe present 44 REV B SEP 1980 Specification 1480 Series SN B060000 up Table 4 1 cont Characteristic Performance Requirement Supplemental Information DC Restorer Mains hum attenuation SLOW position Less than 0 9 dB Change of back porch or sync tip level caused by FAST position More than 26 dB hum Shift caused by absence or presence of burst Less 7 mV CCIR or 1 IRE NTSC Calibrator accuracy 1 00 V 10 296 0 714 V 0 5 NTSC 0 700 V 0 5 CCIR Return Loss INPUT A or B With 75 ohm termination More than 40 dB dc to 5 MHz Any front panel control setting instrument on or off AUXiliary VIDEO INput More than 34 dB dc to 5 MHz Instrument on only AUXiliary VIDEO OUTput More than 34 dB dc to 5 MHz Instrument on only Picture PIX MONITOR OUTput Characteristic Input Resistance Input RC Product More than 34 dB dc to 5 MHz Instrument on only Table 4 2 X10 PROBE INPUT Option 1 Performance Requirement Supplemental Information 1
14. a LOW PASS Switch the RESPONSE to LOW PASS and note that all subcarrier and corners of fast transitions are lost See Fig 1 5b b LUM or IRE Switch the RESPONSE to LUM IRE and note that most subcarrier is lost but the corners of the fast transitions are retained See Fig 1 5c C FLAT Switch the RESPONSE to FLAT and note an undistorted presentation of the composite test signal Fig 1 5d d BANDPASS 4 43 or 3 58 Switch the RESPONSE to BANDPASS and note that only the subcarrier informa tion is presented See Fig 1 5e e DIFFD STEP Switch the RESPONSE to DIFF D STEP and note that each transition is now represented asa spike See Fig 1 5f Unpacking and Incoming Inspection 1480 Series SN B060000 up 2338 04 Fig 1 5 Effects of the various filters on a Composite Test Signal a Applied signal b Low Pass filter c IRE NTSC or Lum PAL d Flat e Bandpass f Diff d Step Unpacking and Incoming Inspection 1480 Series SN B060000 up 5 WAVEFORM COMPARISON Turn the larger OVERLAY knob out of the switch detent note that the WAVEFORM COMPARISON light comes on Rotate the smaller LOCATE knob back and forth slowly and note a small break in the trace and moves back and forth with the rotation of the LOCATE knob Position the break between the pulse and bar components of the composite test signal With the OVERLAY control position the right side of the display so that the pulse lines up dire
15. at tenuation gt 40 dB at 358 MHz and 4 43 MHz Linear Waveform Distortion Pulse Preshool Pulse Overshoot and Pulse Ringing lt 0 5 of applied pulse amplilude 25 us Bar Till lt 0 5 Field Square Wave Tilt lt 1 Pulse to Bar Ratio 0 99 1 to 1 01 1 or 0 99 to 101 1 Non Linear Waveform Distortion Differential Gain Displayed lt 0 5 al any APL AUX VIDEO OUT and PIX MONITOR OUT 0 25 at any APL Differential Phase AUX VIDEO OUT and PIX MONITOR OUT 0 25 at any APL DC RESTORER Mains Hum Altenuation Slow lt 10 Fast gt 26 dB Shift caused by Presence or Absence of Burst 1 IRE or 7 mV Return Loss With 75 Termination INPUT A or B 40 dB DC to 5 MHz AUX VIDEO IN AUX Video OUT or PIX MONITOR OUT 34 dB DC to 5 MHz Vertical Overscan or 1 V Peak to Peak Com posite Video Signal all specifications are valid al 10 05 and 0 2 volts FLLL SCALE and any vertical position selling to 5 MHz Calibrator Accuracy 1 V 02 714 mV and 700 mV 0 5 Timebase Accuracy and Linearity 5 s DIV and 10 4s DIV Accuracy Over Center 10 Div 1 Linearity Overall 1 Magnified Timing and Linearity For center 10 divisions of unmagnified sweep 2 accu racy 2 linearity 2 FIELD Sweep Length and Linearity 127 div 0 5 div FIELD SELECTOR Positive selection of ODD 2 amp 4 or EVEN 1 amp 3 in 525 60 Systems Display starts on selected field Positive selection of 1 2
16. is used for the reinserted test signal The usefulness of this technique is enhanced by its universality The size of the system under test can be anywhere from a Studio to Transmitter Link to a transcontinental network In addition since only the difference between the Insertion Test Signals is to be considered any point in the system can be selected for the reinsertion point with monitoring at any down stream point desired This leaves one major consideration the monitoring operator must know where reinsertion is occurring but with modern distribution systems this is no problem REV A SEP 1980 ihe composite test signal Position ihe leading edge of the bar to the ascending arrow Vertically position the blanking level lo point B on the 0 IRE Unit refer ence line Insertion gain is measured at the bar midpoint see Figure 1 Figure 1 Checking Insertion Gain and Line Time Distortion Insertion Gain unity L D 096 Line Time Distortion Position the composite test signal bar leading edge to the ascending arrow with blanking level on point B If insertion gain is off set the VARiable VOLTS FULL SCALE so that the bar top passes ihrough 100 IRE at its midpoint See Figure 1 To measure line time distortion check the largest deviation of the bar top tilt or rounding within the box This box ignores the first and last 1 usec where short time distortions may be ob served The box provides 2 and 5 L D line t
17. used to intensify the displayed vertical intervals In addition the LINE STROBE OUT was used along with the field switching to control the display on a Vector scope for a quick look at burst phasing Table 1 Field Selector Field Line Number Burst m PAL PAL M PAL PAL M 4 4 623 522 No Yes 1 6 8 No No 1 1 310 259 No Yes 2 319 270 Yes No 2 2 623 522 No No 3 6 8 Yes Yes 3 3 310 259 Yes No 4 319 270 No Yes No burst on either line 622 or line 623 of field 2 Copyright 1977 Tektronix Inc All rights reserved Printed in US A Foreign and U S A Products of Teklronix Inc are covered by Foreign and U S A Patents and or Patents Pending Information in this publication supersedes all previously published material Specification and price change privileges reserved TEKTRONIX TEK SCOPE MOBILE TELEQUIPMENT and fj are registered trademarks of Tektronix Inc P O Box 500 Beaverton Oregon 97077 Phone Area Code 503 644 0161 TWX 910 467 8708 Cable TEKTRONIX More than 50 Subsidiaries Distributors around the world 5 77 3 28 AX 3078 1 REV A SEP 1980 CHARACTERISTICS Application Notes 1480 Series SN B060000 up SCALE FACTOR INPUT A and B 10 Volls Full Screen 1 3 mV 0 5 Volls Full Screen 15 mV 0 2 V F Screen 6 mV Ratio INPUT A to INPUT B 1 0 002 to 1 AUX VIDEO IN to INPUT A 15 03 dB GAIN INPUT A lo AUX VIDEO OUT 1 0 005 INPUT A to PIX
18. 0 2 V full screen with 10X attenualor probe GAIN Range 10 Tilt lt 5 on 50Hz square wave High Frequency Response 1 25 Hz to 5 MHz 3 5MHz to 10MHz Referenced to 50kHz Input Resistance 1 M9 2 not including probe Input RC Product 20 xs 0 5 not including probe BNC connector accepts most TEKTRONIX probes P6065A probe recommended 10X Probe Calibrator Output Voltage 1 000 V x0 005 V or 0 995 to 1 005 V Cabinet Rackmount Dimensions in cm in cm Height 8 25 21 0 5 25 13 3 Width 8 50 21 6 19 0 48 2 Depth 16 95 43 0 18 0 45 7 Weight Ib kg Ib kg Net 21 5 9 8 24 6 11 2 Shipping z28 5 42 9 z53 1 241 Application Notes 1480 Series SN B060000 up 1485R ORDERING INFORMATION 1480C NTSC Waveform Monitor 1480R NTSC Waveform Monitor 1481C PAL Waveform Monitor 1481R PAL Waveform Monitor 1482C PAL M Waveform Monitor 1482R PAL M Waveform Monitor 1485C PAL NTSC Dual Standard Waveform Monitor 1485R PAL NTSC Dual Standard Waveform Monilor Option 01 1 megohm 20 pf probe input probe not included Suggested Probe P6105A 10X Probe 6 ft Order 010 6065 13 9 ft Order 010 6105 05 Option 02 With Carrying Case Cabinet Version Only Option 03 With Blank CRT Option 07 Slow Sweep Option 08 Adds capability of recognizing four field sequence of SECAM 1481C 1481R 1485C 1485R only OPTIONAL ACCESSORIES Mounting Cradles A cradle assembly with associated bezel allows the 1480C Wave form Monitor to be mounte
19. 1813 07A Fig 2 1 Vertical control locations for rackmount left and cabinet model right Operating Instructions 1480 Series SN B060000 up 10 OPER Selects the INPUT signal for normal dis play operation 11 CAL Selects an internally generated squarewave useful for checking vertical gain and the complete or component parts of a composite video signal When CAL is pushed in at the same time as the OPER button the incoming signal at the A Input only is overlayed on the two levels of the calibrator squarewave for quick and accurate evaluation of the video signal amplitude The Calibrator signal amplitude is dependent on the DC Restorer settings Sync Tip 1 V Back Porch 700 mV or 714 mV depending further on which line standard exter nal graticule is being used 12 VERTICAL POSITION Provides positioning in the vertical direction with a ten turn potentiometer 13 GAIN Adjusts amplitude of the displayed signal with the VARiable VOLTS FULL SCALE control in the CALibrated detent position This is usually adjusted by comparing the internal calibrator signal with the calibrated internal graticule 14 TRACE ROTATION Aligns the display with the horizontal graticule lines 15 OPTION 1 X10 PROBE INPUT Bnc connector for use with an external high impedance X10 probe Input amplifier has a gain of 10X to compensate for the probe s attenuation a one volt signal through the X10 probe will appear as one volt o
20. 2 LOSS PADS 28 30 SERIES RESISTOR oO nO SHUNT RESISTOR 1990 1 5 dB LOSS CIRCUITS FOR AUX VIDEO PATH Application Notes 1480 Series SN B060000 up Set black level along the 0 3 reference line and check that the midpoint of the bar top passes through the circle in the Kpa box Then rotate the HORIZONTAL POSITION control until the baseline of the 20T chrominance pulse is located symmet rically within the submarine diagram Figure 4a Figure 4a Measurement of 20T pulse baseline Adjust the 1478 Corrector until the amplitudes of the upper and lower lobes formed by the pulse baseline intersecting with the 0 3 reference line are equal The chrominance luminance gain inequality is then derived from the Corrector reading consult instrument manual Without disturbing this setting check that the crossover point of the baseline coincides with the circle forming the centre of the limit diagram and if necessary adjust the horizontal position to achieve this The peak to peak amplitude of the pair of lobes is then a mea sure of the chrominance luminance delay distortion The pair of horizontal lines correspond to 200 ns which may be considered as a limiting value for a high quality TV system This can be converted to 100 ns and 40 ns respectively by the use of the gain steps of the VOLTS FULL SCALE control This diagram may also be used wilh a 10T chrominance pulse provided the indicated readings are halved The limiting value f
21. 3 or 4 or 1 amp 3 2 amp 4 in 625 50 Systems Display starts on selected field REV A SEP 1980 LINE SELECTOR VARIABLE Range From ap proximately line 20 of the selected field to ap proximately line 8 of the next complementary field example line 20 or field 1 to line B of field 3 Lines inlensitied by the strobe in 2 FIELD display are the lines displayed in 5 ys DIV or 10 us DIV DIGITAL Selects line 9 322 to line 22 335 15 LINE Identical lo VARIABLE except that 15 successive lines are displayed ALL FIELDS Time overlay of all fields any setting of the DISPLAY switch Sync Input Requirements INT 200 mV peak to peak to 2 V peak to peak composite video EXT 400 mV peak to peak lo 2 V peak to peak com posite video 200 mV peak to peak to 8 V peak to peak composite sync Relurn loss gt 46 dB down lo 5 MHz Maximum Jitter with 1 V Peak lo Peak Composite Video 26 dB White Noise Direcl 250 ns AFC 90 ns Maximum Jitter with Missing Horizonlal Sync Pulses 15 ns missing sync pulse maximum of 10 conseculive horizontal sync pulses missing 50 Hz 60 Hz Recognition Automalically recog nizes 50 Hz or 60 Hz scan in dual standard in strument Horizontal Trigger AFC Horiz Frequency 15 750 200 Hz Lock In Time lt 1 sec Maximum Jit ler with Respect to Input Sync 10 ns lInput com Posile Video or Composile Sync from a 140 series Generator 12 ns Variable APL 12 ns Variable APL amp 4 V r
22. 50 Hz signal c Set the 1480 Series DISPLAY selector to 2 FIELD and depress both INT and EXT SYNC pushbuttons d Check for a triggered 1480 Series display of 2 full cycles of square wave e Install the 50 Q X10 attenuator in the cable from the pulse generator to the AUX SYNC INPUT Using the test oscilloscope as an amplitude monitor set the pulse generator for 400 mV at 50 Hz f Check for a triggered 1480 Series display of 2 full cycles of square wave 45 Check 50 60 Hz Triggering Frequency Range a Using the test oscilloscope as an amplitude monitor set the pulse generator amplitude to 1 volt b Rotate the pulse generator frequency control from 50 to 60 Hz and check for a triggered display of 2 full cycles of square wave from 50 to 60 Hz Disregard a small jump that occurs near 55 Hz This is normal and provides for almost identical sweep length at 50 and 60 Hz 5 13
23. 5b and 5c Figure 5a Signal with random noise FLAT response 3 3 Application Notes 1480 Series SN B060000 up Figure 5b As Figure 5a but IRE response Figure 5c As Figure 5a but LOWPASS response Use of Overlay Yet a further improvement can be effected by the use of the overlay facility of the 1480 Series which makes it possible to bring the bar top and the sync pulse bottom into the same vertical axis with the result that the correct adjustment of level is achieved with the two reference points actually overlaid Apart from the added convenience of use this provides a small but significant improvement in resolution since it is easier to adjust for minimum thickness of line than it is to ensure that the two reference points lie on the same horizontal graticule line The appearance of the display with both a correct and an in correct adjustment is shown in Figures 6a and 6b Sync bottom coincident with center of bar top Figure 6a Use of OVERLAY level correct 3 4 Sync bottom vertically above bar top but seperated from st Figure 6b As Figure 6a but level 5 low Measurement of Picture Component So far the setting of video level has been described entirely in terms of the overall one volt amplitude of the signal How ever it is often required to check the amplitude of the pic ture component in addition This is quite simply brought about by changing the DC RESTORER button from SY
24. CRT Option 07 Slow Sweep Option 08 Adds capability of recognizing four field sequence of SECAM 1481C 1481R 1485C 1485R only TEKTRONIX Automatic Correction Products are also available for 525 60 NTSC systems m Tektronix COMMITTED TO EXCELLENCE P O Box 500 Beaverton Oregon 97077 US A 3 19 Application Notes 1480 Series SN B060000 up TEKTRONIX E Enhanced Video Measurement Capability Using the 15 Line Display of the TEKTRONIX 1480 Series Waveform Monitors U v VV La aad television application note no 15 As the television industry has come of age the viewing public along with the technicians and engineers of the industry has become an extremely critical judge of picture quality This critical judgement forces the broadcaster to adopt ever more sophisticated measurement techniques requiring greater accuracy in test methods and test equipment For years the same general video measurement techniques or difficult special tests have been used on video tape recorders This would be fine if only machine characteristics such as frequency response transient response or signal non linearity were involved However many of the important performance characteristics of modern VTR systems are related to the individual heads their equalizers and preamplifiers rather than to overall VTR performance This application note deals primarily with assessing the performance of individual heads but does not ignore such VTR
25. Connect the video signal source composite sync to EXTERNAL SYNC A input connector b Set the VOLTS FULL SCALE selector to 1 0 MAGNIFIER switch to OFF RESPONSE selector to FLAT and DISPLAY selector to 2 FIELD Press the SYNC DIRECT and EXT pushbuttons c Set the Sync Input Selector on the rear panel to EXT SYNC ALWAYS A and check for a stable display d Move the composite video to the VIDEO INPUT B connector set the INPUT selector to B and check for a stable display e Change the Sync Input Selector to EXT SYNC SWITCHED WITH INPUT SWITCH A or B and check that the display is not locked f Move the composite sync input to the EXTERNAL SYNC B connector and check for a stable display 33 Check Return Loss a Connect the return loss bridge output connectors to the test oscilloscope differential comparator inputs Connect the leveled sine wave generator output through the 50 Q to 75 Q minimum loss attenuator to the return loss bridge Input connector Set the test oscilloscope differential comparator for differential operation and Volts Div to l b Set the leveled sine wave generator for 50 kHz Check that the 75 Q termination is not connected to the Unknown Arm of the return loss bridge and adjust the Performance Verification 1480 Series SN B060000 up leveled sine wave generator amplitude for a 500 mV display on the test oscilloscope c Connect the return loss bridge unknown arm to the VIDEO INPUT A co
26. FIELDS Time overlay of all fields any setting of the DISPLAY switch Sync Input Requirements INT 200 mV peak to peak to 2 V peak to peak composite video EXT 400 mV peak to peak to 2 V peak to peak com posile video 200 mV peak to peak to 8 V peak to peak composite sync Return loss gt 46 dB down to 5 MHz Maximum Jitter with 1 V Peak lo Peak Composite Video 26 dB White Noise Direct 250 ns AFC 90 ns Maximum Jitter with Missing Horizontal Sync Pulses 15 ns missing sync pulse maximum of 10 consecutive horizontal sync pulses missing 50 Hz 60 Hz Recognition Aulomatically recog nizes 50 Hz or 60 Hz scan in dual standard in strument Horizontal Trigger AFC Horiz Frequency 15 750 200 Hz Lock In Time lt 1 sec Maximum Jil ter with Respect lo Input Sync 10 ns Input com posite Video or Composite Sync from a 140 series Generalor 12 ns Variable APL 12 ns Variable APL amp 4 V rms Hum 30 ns Variable APL amp 4 V rms Hum 36 dB White Noise Jitter Reduction with Respect to While Noise 8 dB DIRECT Horiz Frequency Range lt 20 kHz Maximum Jitter with Respect to Input Sync 12 ns input Composite Video or Composite Sync from a 140 series Generator 20 ns Variable APL 20 ns Variable APL amp 4 V rms Hum 90 ns Variable APL amp 4 V Tum 36 dB White Noise EXTERNAL HORIZ IN Sensitivity 05 V div Linearity 1 RGB YRGB J9036 RGB Sweep Length Inter
27. Hum Attenuation Slow lt 10 Fast 26 dB Shift caused by Presence or Absence of Burst 1IRE or 7 mV Return Loss With 75 Termination INPUT A or B gt 40 dB DC to 5 MHz AUX VIDEO IN AUX Video OUT or PIX MONITOR OUT 34 dB DC to 5 MHz Vertical Overscan lor 1 V Peak lo Peak Com posite Video Signal all specifications are valid at 10 05 and 02 volts FLLL SCALE and any vertical position setting to 5 MHz Calibrator Accuracy 1 V 02 714 mV and 700 mv 05 Timebase Accuracy and Linearity 5 ys DIV and 10 us DIV Accuracy Over Center 10 Div 1 Linearity Overall 1 Magnified Timing and Linearity For center 10 divisions of unmagnified sweep 2 accu racy 2 linearity 2 FIELD Sweep Length and Linearity 127 div 0 5 div FIELD SELECTOR Positive selection of ODD 2 amp 4 or EVEN 1 amp 3 in 525 60 Systems Display starts on selected field Positive selection of 1 2 8 or 4 or 1 amp 8 2 amp 4 in 625 50 Systems Display starts on selected field REV A SEP 1980 LINE SELECTOR VARIABLE Range From ap proximately line 20 of the selected field lo ap proximately line 8 of the next complementary field example line 20 or field 1 to line 8 of field 3 Lines intensified by the strobe in 2 FIELD display are the lines displayed in 5 amp s DIV or 10 us DIV DIGITAL Selects line 9 322 to line 22 335 15 LINE Identical to VARIABLE excep thal 15 successive lines are displayed ALL
28. LINE SELECTOR VARIABLE Range From ap proximalely line 20 of the selected field lo ap proximately line 8 of the next complementary field example line 20 or field 1 to line 8 of field 3 Lines intensified by the strobe in 2 FIELD display are the lines displayed in 5 s DIV or 10 xs DIV DIGITAL Selects line 9 322 to line 22 335 15 LINE Identical lo VARIABLE excep thal 15 successive lines are displayed ALL FIELDS Time overlay of all fields any setting of the DISPLAY switch Sync Input Requirements INT 200 mV peak to peak to 2 V peak to peak composite video EXT 400 mV peak to peak to 2 V peak to peak com posite video 200 mV peak to peak to 8 V peak lo peak composite sync Return loss gt 46 dB down lo 5 MHz Maximum Jitter with 1 V Peak to Peak Composite Video 26 dB White Noise Direct 250 ns AFC 90 ns Maximum Jitter with Missing Horizontal Sync Pulses 15 ns missing sync pulse maximum of 10 consecutive horizontal sync pulses missing 50 Hz 60 Hz Recognition Automatically recog nizes 50 Hz or 60 Hz scan in dual standard in strument Horizontal Trigger AFC Horiz Frequency 15 750 200 Hz Lock In Time 1 sec Maximum Jit ler with Respect to Input Sync 10 ns Input com posite Video or Composite Sync Irom a 140 series Generator 12 ns Variable APL 12 ns Variable APL amp 4 V rms Hum 30 ns Variable APL amp 4 V rms Hum 36 dB While Noise Jitter Reduction with Respect to
29. Measure the amplitudes of the largest and the smallest as accurately as possible let these be A and A max respeclively Then the percentage non linearity dis max tortion is given by mi X100 which may more conve niently be calculated if the amplitude of the largest pulse A pax is made 7 graticule divisions 0 7V The expression then sim plifies to 1 1 4 A X100 min In very many instances it is possible to utilize the VOLTS FULL SCALE VAR control to set the largest pulse to 10 graticule divi sions by making it extend from the O line to the 1 0 line when the distortion is given even more simply by 1 A X100 and the calculation required is minimal Another way of comparing the amplitudes of the differentiated pulses which is sometimes useful is to make use of the OVER LAY facility by means of which any pair of pulses can be over laid and their amplitude difference made clearly visible Both the increase of amplitude to 10 divisions and the use of the overlay facility are illustrated in Figure 5 Figure 5 Measurement of differentiated pulse amplitudes using OVERLAY REV A SEP 1980 Application Notes 1480 Series SN B060000 up Part 6 Video Level Measurement Control Settings MAG OFF Others As under Part 1 Note the VAR VOLTS FULL SCALE con trol must be in the CAL position A rapid estimate of the amplitude of the video signal can be obtained under operational conditions by the followin
30. Range From ap proximately line 20 ol Ihe selecled field to ap proximately line 8 of the next complementary held example line 20 or field 1 to line 8 of field 3 Lines intensified by the strobe in 2 FIELD display are the lines displayed in 5 s DIV or 10 us DIV DIGITAL Selects line 9 322 to line 22 335 15 LINE Identical to VARIABLE except that 15 successive lines are displayed ALL FIELDS Time overlay of all fields any setting cf the DISPLAY switch Sync Input Requirements INT 200 mV peak to peak to 2 V peak to peak composite video EXT 400 mV peak to peak to 2 V peak to peak com posite video 200 mV peak to peak lo 8 V peak to peak composite sync Return loss 46 dB down lo 5 MHz Maximum Jitter with 1 V Peak to Peak Composite Video 26 dB White Noise Direct 250 ns AFC 90 ns Maximum Jitter with Missing Horizontal Sync Pulses 15 ns missing sync pulse maximum of 10 consecutive horizontal sync pulses missing 50 Hz 60 Hz Recognilion Avtomatically recog nizes 50 Hz or 60 Hz scan in dual slandard in strument Horizontal Trigger AFC Horiz Frequency 15 750 200 Hz Lock In Time 1 sec Maximum Jil ler with Respect to Input Sync 10 ns Input com posite Video or Composite Sync from a 140 series Generator 12 ns Variable APL 12 ns Variable APL amp 4 V rms Hum 30 ns Variable APL amp 4 V rms Hum 36 dB White Noise Jitter Reduction with Respect to While Noise 8 dB DIRECT Ho
31. Range reduced by one half anywhere on 5 us DlVision or with magnified 10 us DIVision 10 us DIVision unmagnified sweep sweep OVERLAY Range Will overlay the selected 5 us DIVision or 10 us portion of sweep marked by the locate index on portion DIVision unmagnified index of the sweep preceding the LINE STROBE OUTPUT Incidence and duration dictated by line selection TTL amplitude Line Selection Variable VAR selects a single line from approximately line 20 of the selected field see Field Selection through the next field and vertical interval to approximately line 8 Any line intensified in 2 FIELD will be the one displayed in 5 us DlVision or the first line displayed in 10 us DIVision sweep speeds 2FIELD Vv 15 LINES operation covers the same range but inten sifies a block of 15 consecutive lines In 2 FIELD display this intensification shows up as a block of lines At 10 us DIVision a two line display of increased brightness starting with the first intensified line in 2 FIELD will be seen At 5 us DlVision a single brightened line will be seen again beginning with the first intensified line See Figure 4 2 1813 2338 22 Fig 4 2 15 Line display mode 4 10 Digital DIG selects any one of 13 lines the 9th through the 22nd of the selected field this includes lines 322 through 335 PAL and 272 through 285 PAL M In 2 FIELD displays the digitally selected line is
32. SCALE selector to 1 0 RESPONSE selector to FLAT DISPLAY selector to 10 us DIV and MAGNIFIER switch to OFF c Press the LINE SELECTOR DIG and EVEN FIELD pushbuttons d Again set the video signal source for known signals in the vertical interval e Check that the line displayed and the line selected by the 1480 Series LINE SELECTOR switch agree f Press the LINE SELECTOR VAR pushbutton and set the DISPLAY selector to 2 FIELD Rotate the VAR control and check that the selected line is intensified and that the intensified zone can be moved the width of the display with the VAR control g Press the LINE SELECTOR 15 LINES pushbutton Rotate the VAR control and check that fifteen consecutive lines can be intensified and the zone can be moved the width of the display with the VAR control 30 Check PIX MONITOR OUT and LINE STROBE OUT a Connect the video signal source composite video signal to the VIDEO INPUT A connector 5 10 b Set the RESPONSE selector to FLAT DISPLAY selector to 2 FIELD VOLTS FULL SCALE selector to 1 0 and MAGNIFIER switch to OFF c Press LINE SELECTOR VAR pushbutton d Connect the PIX MONITOR OUT connector througha75 Q termination to the test oscilloscope vertical input e Check thatthe line selected by the LINE SELECTOR controls is identified on the 1480 Series display by an intensified zone and on the test oscilloscope display by a 200 mV pedestal The pedestal should be one line dura t
33. White Noise 8 dB DIRECT Horiz Frequency Range 20 kHz Maximum Jitter with Respect to Input Sync 12 ns input Composite Video or Composite Sync from a 140 series Generator 20 ns Variable APL 20 ns Variable APL amp 4 V rms Hum 90 ns Variable APL amp 4 V Tum 36 dB White Noise EXTERNAL HORIZ IN Sensitivity 05 V div Linearity 196 RGB YRGB J9036 RGB Sweep Length Inter nally selected for Y5 normal sweep YRGB Sweep Length internally selected for t4 normal sweep WAVEFORM COMPARISON LOCATE Range suf ficient to place LOCATE indication any place on 5 s DIV or unmagnified 10 ps DIV sweeps OVERLAY Range sullicient to overlay any se lected portion of 5 us DIV or unmagnitied 10 us DIV on any other portion LINE STROBE OUT Strobe output of line or lines selecled by VARIABLE 15 LINE or DIGI TAL line setector modes and the DISPLAY Switch TTL amplilude ac coupled Time Con stant 1 uF 10 kt OPTION 1 10X Probe Channel Scale Factor adjustable to 1 V peak to peak equivalent display height GAIN Range 10 Gain to AUX VIDEO Unity 3 with gain adjusted for 1 V peak to peak equivalent display height Tilt 5 on 50 Hz square wave High Frequency Response 195 25 Hz to 5 MHz 3 5 MHz to 10 MHz Referenced to 50 kHz Differential Phase 025 al any APL Differen tial Gain 0 25 at any APL Input Resistance 1 Mt 2 not including probe Input RC Product 20 ys 05 not includ
34. a X1 probe for signal acquisition permits ten times signal gain and is useful for low signals such as hum or residual subcarrier 2 11 Operating Instructions 1480 Series SN B060000 up Using the RGB YRGB Input J9034 J9034 provides control and signal access for stepping the Waveform Monitor Sweep with the RGB or YRGB staircase The encoded line rate or field rate camera pick up tube parade signal can then be applied to one of the VIDEO INPUTS and the various pick up tube matching adjustments can be easily made J9034 pin D is the access for sweep length alteration Grounding this point shortens the sweep allowing the RGB YRGB stair case to step the parade across the crt so that the outputs of the camera pick up tubes are seen on the same display The RGB YRGB staircase is applied to J9034 pin C The staircase repositions the shortened sweep The sweep is not shortened in time only in distance traveled across the crt A mating male plug P9034 is available for applying external RGB YRGB input signals to J9034 See Accessories in the rear of this manual for ordering information It is possible to alter the length of the sweep by changing the value of two resistors Since this is a circuit change it should be attempted only by a qualified technician Information on these values changes can be found in Section 6 of the SERVICE part of this manual 1480 Series instruments are shipped with plug jumpers P4032 an
35. by a 147 147A when full line deletion at a 100 IRE level is selected Figure 7b shows the same mea surement made with the Composite waveform which it must be noted is less sensitive Figure 7 Field Time Distortion observed from VIT Signals a A full line 100 IRE pedestal from a 147 1474 b A Composite Test Signal This technique is obviously less sensitive but will display enough field time distortion field time tilt to be a useful in service measurement technique The versatile TEKTRONIX 1480 Series Waveform Monitor is ideally suited for routine operating signal analysis or labora tory investigations This application note deals with only one display mode All Fields for further application information contact the nearest Tektronix Field Office or representative REV A SEP 1980 Votos espouse m nA e e Q0 1485C CHARACTERISTICS VERTICAL DEFLECTION Inputs input A and B are 759 high impedance loop through Return loss is gt 40dB from Dc to 5MHz in a 759 system Aux Video Input is internally terminated in 759 Relurn loss is 234 dB from Dc to 5 MHz Scale Factor A and B input calibrated 1 0 0 5 0 2 volts full scale Variable Range for each scale factor at least 4096 to 50 Aux Video Input 1 5 dB gain Max Input Voltage 2 volts peak to peak Ac coupled Frequency Response Flat Flat to 5 MHz 0 5 MHz to 10MHz 0 5 596 Low Pass nuation gt 14dB S00 kHz and above 3 58
36. can be improved by using the VOLTS FULL SCALE control as a multiplier and resetting the vertical position so that the centre of the bar again passes through the circle The two steps con vert the box limits of 5 into 2 and 196 respectively The appearance of the display during this measurement is given by Figure 1 This figure is satisfactory for use as a rouline check but it has been obtained from a 10 us bar instead of the 25 us bar specified for K rating purposes A common way out of this difficulty is to double the 10 us bar value to give a K com parable with the figure which would be obtained with a 25 us bar Note If there is any serious till of black level on the video signal there is an ambiguity in the setting of black level against the 0 3 line It can be shown that the minimum error is obtained when the trace coincides with this reference line at the point marked B on the graticule Figure 1 Measurement of K and K phe Part 2 Ky Control Settings MAG x25 200 ns div Others As in Part 1 Turn the HORIZONTAL POSITION contro until the 2T pulse is located symmetrically within the submarine tolerance dia gram with black level lying along the 0 3 line and the peak of REV A SEP 1980 the pulse coinciding with the 1 0V line as in Figure 2a the variable gain control will usually be required to achieve this The symmetrical positioning of the pulse is best checked against the pair of uppermost lines
37. delay in one signal path only is completely avoided by insert ing the filler in the AUX VIDEO circuit Most usually the basic loss of the filler is less than the 1 5 dB gain provided in the AUX VIDEO channel It is then preferable to insert an attenuator pad of the correct value in series with the filter so as to make the AUX VIDEO gain unity while at the same time preserving the 759 circuit impedance This will ensure that the calibration of the waveform monitor remains the same in both conditions of use Details of suitable types of pad are given in Appendix I Insertion of Measuring Equipment Video measuring equipment whose output requires a waveform monitor display can be inserted in series with ihe AUX VIDEO path whenever desired without breaking the input video feed A case in point is described in some detail in Application Note 712 Part 4 where a TEKTRONIX 1478 Calibrated Chrominance Level Corrector is employed for the measurement of chro minance luminance gain and delay inequalities With this kind of connection it becomes possible to make measurements freely under in service conditions with no fear that the use of the equipment will modify ihe video signal and become obvious to the viewer For the same reason the measuring equipment may be removed or interchanged without any effect on the video feed REV A SEP 1980 Application Notes 1480 Series SN B060000 up It is also possible to make use of the VIDEO OUT facility to
38. drive another instrument simultaneously from ihe same signal For instance a vectorscope can be added when required with out disturbing the normal utilisation of the waveform monitor Operational Networks Tektronix has incorporated into the 1480 Series Ihe widest practicable range of operational nelworks that is chrominance and luminance separating filters and so on However il is obviously not possible to anticipate all user requirements and in fact it may well happen that these needs will change with time The AUX VIDEO path provides the ability io add or to modify networks as the situation demands thus ensuring a great deal of flexibility and a degree of protection against obsolescence Equaliser Design Coaxial cable possesses a loss characterislic giving a steadily increasing attenuation with frequency so in order to maintain ihe distortion at an acceplably low level it is necessary to equalise long cable runs It will be shown that the AUX VIDEO facility can be utilised as a very simple and efficient means of designing these networks There are two approaches to video equaliser design In the firsl one measures the response to be equalised and then calculates the element values of the network best fitting the inverse of this response over Ihe video band In the second advantage is taken of the fact that highly slandardised TV tesl waveforms are now readily available to obtain the equaliser values directly by inserting in se
39. for 10 us markers b Apply a trigger from the time mark generator to the EXTERNAL SYNC A input connector c Press SYNC EXT and DIRECT pushbuttons d DISPLAY is at 10 us DIV e Check for a display of 1 time mark div within 2 f Set the MAGNIFIER switch to 0 1 us DIV and the time mark generator for 0 1 us marks g Check the magnified display for 1 mark div 3 over the center 10 divisions of the unmagnified display Total effective magnified display is 1270 divisions in length 12 7 div magnified 100X Specification appliesto any portion of the center 1000 divisions at this magnifica tion h Check magnified timing and linearity as in Table 5 3 Table 5 3 TIME MARKERS MAG DISPLAY LIMIT 14s 0 2 us 1 mark 5 div 3 1 us 0 25 us 1 mark 4div 3 1 us 0 5us 1mark 2div 2 14s 104s 1 markdiv 1 25 Check WAVEFORM COMPARISON Range a Set the DISPLAY switch to 5 us DIV and rotate the WAVEFORM COMPARISON OVERLAY control just out of detent Notice the small blanked portion of the trace b Rotate the WAVEFORM COMPARISON LOCATE control to place the blanked portion at the start of the trace c Rotate the WAVEFORM COMPARISON OVERLAY control throughout its range d Check that the OVERLAY control has sufficient range to position the display completely off screen e Set the DISPLAY switch to 10 us DIV and repeat this step 26 Check RGB YRGB Operation a Connectthe
40. io compensate for about 3 parallax error Using an external graticule same Scale size as the internal graticule for visual monitoring will provide a parallax error of 1 or less Visual unmarked graticules should not be used for wave form photography Using Graticule A The primary test signal in this application note is an NTSC composite test signal generally a Vertical Interval Test Signal VITS The composite test signal can be either the one required by the FCC 873 669 for remote transmitter control or the CCIR composite VITS for interna lional program exchange CCIR Rec ommendation 473 Annex Il 525 line systems adopted 1974 While the graticule special scales pro vide 2 resolution increments at 1 0 VOLTS FULL SCALE greater resolution is provided by the 1480 Waveform Monitor s calibrated vertical expansion A 1 0 volt video signal can be expanded 2X or 5X without loss of accuracy pro viding direct resolution of up to 0 296 for some of the measurements thal follow Calibration Checks Time base calibra lion accuracy can be checked with just the video signai The 5 and 10 us DIV time bases are checked by measuring the time duration of 1 or 2 lines 63 5 usec or 127 usec The 0 1 and 0 2 us DIV time bases are checked by measuring burst period against the scale tick marks on the 30 IRE Unit line Vertical gain which may be reset from the front panel is easily checked by using the 1480 s buill in ca
41. is carried out as follows Set the con trols as given above and rotate the HORIZONTAL POSITION contro until the trailing edge of the bar is within the display area Adjust the gain so that the top and bottom of the bar fit exacily between the 0 and 1 0 graticule lines then position the display so that the bottom of the bar lies on the 0 2 line and at the same time the trailing edge coincides with the intersection of the1 1line and the graduated scale Figure 8 The time of fall can then be read from the horizontal spacing between the small vertical 5 scale and the point where the bar edge cuts the 0 3 graticule line Copyright 1974 Tektronix Inc All rights reserved Printed in U S A Foreign and U S A Producls of Tektronix Inc are covered by Foreign and U S A Palents and or Palents Pending Information in this publication supersedes all previously published material Specification and price change privileges reserved TEKTRONIX SCOPE MOBILE TELEQUIPMENT and ge are regislered trademarks of Tektronix Inc P O Box 500 Beaverton Oregon 97005 Phone Area Code 503 644 0161 Telex 36 0485 Cable TEKTRONIX Overseas Distributors in over 40 Countries AX 3070 3 10 9 74 REV A SEP 1980 CHARACTERISTICS Application Notes 1480 Series SN B060000 up SCALE FACTOR INPUT A and B 1 0 Volts Full Screen 1 3 mV 0 5 Volts Full Screen 15 mV 0 2 V F Screen 6 mV Ratio INPUT A to INPUT B 1 0 002 to 1
42. machine problems as time base instability jitter distorted or missing sync pulses or field time distortion In order to accurately evaluate VTR head performance of modern quadruplex machines a novel waveform monitor 2 FIELD EEE display mode had to be adopted The TEKTRONIX 1480 Series Waveform Monitors incorporate this new 15 line display mode While its primary application is to VTR head evaluation other applications where selected groups of lines must be looked at provides this mode with extra versatility This display mode selects 15 adjacent lines and displays them one on top of the other as shown in Figure 1 Using the 15 line display mode provides a much brighter display than a line selected one 1H or two 2H line display but still does not confuse the operator with extraneous information as would happen in a full field display The following paragraphs will show how to use the 1480 Series Waveform Monitor 15 line display mode to evaluate each individual head of a quadruplex VTR for signal to noise ratio and non linear distortion differential gain and differ ential phase In addition to the 1480 Series Waveform Moni tor a noise measurement system such as the TEKTRONIX 1430 or the 147 147A NTSC 148 PAL or 148 M PAL M and a Vectorscope 520 520A NTSC 521 521A PAL or 522 522A PAL M are required Figure 1 15 line display mode Any 15 lines may be selected and displayed overlaid Copyright 19
43. mode both OPER and CAL are pressed superimposing the A VIDEO INPUT signal on the calibrator waveform Signal amplitude errors are easily distinguished by noting differences between the bottom of the upper display and top of the lower display Using the DC RESTORER The DC RESTORER clamps either the back porch or the sync tip of the composite video waveform to 0 V The two rates of restoration FAST and SLOW allow the user to compare the signal in the presence of hum to the signal with hum attenuated The FAST mode attenuates mains hum by at least 26 dB while the SLOW mode attenuates by 0 9 dB or less In addition an internal jumper can be changed to increase the fast clamp restorer speed This jumper P1993 should only be changed by a qualified technician because this change requires the removal of the protective covers Instructions for this and other program changes appear in Section 6 of the SERVICE part of this manual REV A SEP 1980 Operating Instructions 1480 Series SN B060000 up In the fast slew rate rapid restoration is accomplished but the circuit is more susceptible to noise In the slower of the fast slew rates the one normally programmed at the factory the dc restorer is less susceptible to noise but is takes longer to clamp Clamping at the back porch is automatically selected internally when RESPONSE is in LOW PASS Rise and fall of sync pulses in LOW PASS are so low that there is no sync tip left to clam
44. of a knob These should be sufficient for practical purposes As an illustration of the applications of this new graticule in conjunction with the 1480 Series of waveform monitors a brief summary of a suggested measurement procedure is given below It should be noted that apart from the initial settings and ihe inevitable readjustments of positioning controls and gain only a single control needs to be moved throughout the series of measurements Measurement Procedure Part 1 K and K bar ph Control Settings Line Selector 17 and DIG FIELD 1 and 3 together DC RESTORER BACK PORCH FAST MAG OFF DISPLAY 5 us div RESPONSE FLAT VOLTS FULL SCALE 1 0 Set the start of the trace against the left hand edge of ihe 3 6 wiwiurnoe 12 graticule and by using the VOLTS FULL SCALE VAR control in conjunction with the horizontal and vertical positioning con trols set the waveform so that black level coincides with the 0 3 line the centre of the bar top passes through the circle in the Ka box and the bar transitions pass through the pair of circles below the box The value of K is then read as the largest of the deviations of the bar top from the central horizontal line whether above or below between the vertical lines forming the ends of the box The value of K can also be obtained from the position of the peak of the 2T pulse on the scale marked K If K is appreciably less than 5 the reading accuracy
45. of a quadruplex videotape machine overlaid to show differential chroma gain between them Figure 4 Picture monitor display showing selected 15 lines Notice how easily each head of the VTR can be identified Figure 5 Difference in differential gain between two ad jacent video heads as observed on a 1480 Series Waveform Monitor Head Signal to Noise Ratio Measurements Video signal to noise ratio of each individual head can be measured using the 1480 Series Waveform Monitor 15 line display mode in conjunction with the Tektronix developed noise measurement by comparison technique A TEKTRONIX 147 147A NTSC Test Signal Generator or 148 148 M Insertion Test Signal Generator PAL or PAL M which include the noise measurement feature or the TEKTRONIX 1430 Random Noise Measuring Set can be used In the case of the 147 3 21 Application Notes 1480 Series SN B060000 up 147A 148 or 148 M external low pass filters should be employed between the generator and the 1480 Series Wave form Monitor Use a 4 2 MHz low pass filter with the 147 147A or 148 M and a 5 MHz low pass filter with the 148 The 1430 contains its own filter and does not require the use of external filters Figure 6 shows the equipment connections for signal to noise measurements on a head by head basis A length of tape is recorded with a flat field signal and played back The TEKTRONIX 1430 147 147A 148 or 148 M provides the cali brated noise insertion fo
46. so by correctly placing the 15 line display the Waveform Monitor can show each head individually or it can show the transition between any two consecutive heads Head identification and correct place ment of the intensified portion may at first seem difficult but is actually quite easily done By slightly misadjusting REV A SEP 1980 Application Notes 1480 Series SN B060000 up the VTR s female tape guide and viewing the signal before any time base correction is applied the characteristic scalloping of the picture seen on the picture monitor indicates the area scanned by each head Figure 4 shows the picture monitor display used to locate each head When the VTR is operating in the home track mode the first sixteen lines of the field starting with the serrated vertical pulse are covered by head number 4 The first lines shown in figure 4 are from head number 2 making the sequence of head passes 4 2 3 1 4 etc The brightened portion in figure 4 indicates that we are looking at head number 1 After the head has been located in this manner the female tape guide is returned to its correct position and the desired test or adjustment is made If it is desired to compare the characteristics of two adjacent heads the brightened portion of the picture is positioned to straddle the two heads and the Waveform Monitor then dis plays the output of these heads overlaid one on another for easy comparison Figure 5 shows two heads
47. the AUX VIDEO path is functionally an alternative to the built in range of networks available by the use of the RESPONSE control but with the advantage of being isolated from the normal signal path by means of buffer amplifiers It is provided with pre cision 752 input and output terminations and an overall gain of 1 5 dB This means that 7582 passive networks can be inserted without fear of reflection effects and that gain is available to compensate for their basic loss The calibration will then be correct whichever path is in use The advantages of this facility are illustrated by the following examples PROBE IN INPUT SELECT 752 AUX VIDEO Noise Reduction by Band Limitation It is not always realised that the random noise associated with a video signal often possesses a bandwidth extending surprising ly far above the nominal upper limit of the video band This comes about because the video signal spectrum is limited by aperlure and other effects whereas the equipment handling it is commonly made to have a wide bandwidth lo minimise dis lortion In such instances it follows that the signal to noise ratio can be improved at the cost of only a small signal impairment by limiting the bandwidth to its nominal value by means of a de lay compensated lowpass filter of suitable design This is especially effective with signals which have been transmitted over long microwave links where the noise spectrum tends to rise
48. three values as determined by front panel switches With the CAL and SYNC TIP DC RESTORER buttons pressed the squarewave amplitude is one volt No other value is possible or needed since all television standards employ a one voltinto 75 Q composite video signal Adjustment of the front panel GAIN control in this mode is simply a matter of adjusting until the calibrator display coincides with the appropriate internal graticule markings Measur ing the distance from blanking to peak white is not so straight forward since different television standards employ different amplitudes Dual standard models of the 1480 Series use a precise resistor divider with taps for different values Which tap is used in determined by the setting of the Back Porch Cal Ampl switch and the position of the SCALE ILLUM switch The Back Porch Cal Ampl switch is located inside the crt bezel below the crt When external graticule lighting is desired pull the SCALE ILLUM control out This also enables the Back Porch Cal Ampl switch to control signal amplitude The setting of the Back Porch Cal Ampl switch is determined by a hole in the external graticule into which the switch thumb slidefits NTSC graticules setthe slideswitchtothe 714 mV tap on the resistor divider CCIR graticules set the slide switch to the 700 mV position See Fig 2 1 and CAUTION note under External page 2 9 The calibrator signal is particularly useful in the additive calibrator mode In this
49. to 97 5 0 35 MHz 70 to 80 1 MHz 31 2 to 42 5 2 MHz 5 6 to 14 3 6 MHz 4 MHz Fig 4 1 IRE Standard 23S 1 1958 REV A MAY 1980 4 3 Specification 1480 Series SN B060000 up Table 4 1 cont Characteristic Performance Requirement Supplemental Information Filters IRE Conforms to IRE Standard 238 1 1958 See Figure 4 1 At least 22 dB down at 4 43 MHz Luminance Less than 3 dB down at 1 MHz At least 40 dB down at 4 43 MHz Low Pass At least 14 dB down at 500 kHz and above Bandpass 3 58 MHz 1 of flat at 3 58 MHz 3 dB between 3 1 and 3 4 MHz and 3 8 amp 4 0 MHz 4 43 MHz 1 of flat at 4 43 MHz 3 dB between 3 9 amp 4 1 MHz and 4 7 amp 4 9 MHz Differentiated Steps Diff d Steps Less than 2 dB 0 4 MHz to 0 5 MHz At least 20 dB 14 kHz and 2 0 MHz At least 40 dB 3 58 MHz and 4 43 MHz Linear Waveform Distortion Pulse preshoot overshoot and ringing Less than 0 5 of applied pulse amplitude Vertical gain increase approximately 5 times to compare staircase risers 25 us bar tilt Less than 196 of applied pulse amplitude Pulse to bar ratio 0 99 1 to 1 01 1 Field squarewave tilt Less than 1 of applied squarewave amplitude Non Linear Waveform Distortion Differential gain displayed Less than 0 5 any APL AUXiliary VIDEO OUTput Less than 0 259 any APL Picture PIX MONITOR
50. to B Input Gain Ratio a Set the test signal generator Variable APL or Peak White to 100 and the 1480 Series VOLTS FULL SCALE selector to 1 0 b Check display amplitude 1 0 volt or 140 IRE from sync tip to peak white 0 42 IRE NTSC or 3 mV CCIR Note exact amplitude c Change the video input cable to the 1480 Series VIDEO INPUT B connector and change the 75 ohm termination to the VIDEO INPUT B loop thru connector Change the 1480 Series INPUT switch to B DC CPL D d Check display amplitude and compare to that noted onthe AINPUT A B 2 mV CCIR or0 28 IRE NTSC 9 Check VARIABLE VOLTS FULL SCALE Range a Check the amplitude of the sync pulse 40 IRE NTSC or 300 mV CCIR b Rotate the VARiable VOLTS FULL SCALE control just out of detent and check sync pulse amplitude 56 IRE NTSC or 420 mV CCIR or more c Rotate the VARiable VOLTS FULL SCALE control fully counterclockwise and check the sync pulse amplitude for minimum amplitude 20 IRE NTSC or 150 mV CCIR or less d Return the VARiable VOLTS FULL SCALE control to its detented position 10 Check AUX VIDEO IN Response Change a Connect a color bar test signal from the video signal source to the 1480 Series VIDEO INPUT A connector Connect the VIDEO INPUT A loop thru connector to the AUX VIDEO IN connector Do not terminate Set the RESPONSE switch to FLAT and the DISPLAY switch to 5 us div Note the amplitude difference between the tops of the
51. video signal source composite video to the VIDEO INPUT A connector and terminate the loop thru connector in 75 Q REV B SEP 1980 Performance Verification 1480 Series SN B060000 up b Set the INPUT switch to A AC CPL D DISPLAY Switch to 10 us DIV and the MAGNIFIER selector to OFF C Press the SYNC INT and DIRECT pushbuttons d Connect J9034 on the rear panel for RGB YRGB operation ground pin D and connect RGB YRGB steps to pin C e Connect a 3 step staircase from the television test signal generator to J9034 pin C and set the television test signal generator amplitude control for three video lines in 12 7 div If the 1480 Series is internally programmed for YRGB substitute a 4 step staircase See Accessories in the rear of this manual for information on mating male plug P9034 for use with J9034 f Check for a stable display centered without com pression g Set the DISPLAY selector to 2 FIELD and check fora display that is three fields in 12 7 divisions Four fields if connected for YRGB 27 Check EXTERNAL HORIZ input if activated For information on how to activate the External Horizontal mode refer qualified service personnel to OPERATING CHANGES in Section 6 Installation a Set the DISPLAY switch to EXT b Connect a 5 volt positive going ramp from the ramp generator to the EXT HORIZ input c Check for a trace that is 10 0 div 3 28 Check Field Selection a Apply a composite vi
52. with increasing frequency and the greater part of the noise power lies at the higher frequencies An example of this is given in the photographs of Figures 2a and 2b where the spectrum of the random noise was quasi triangular In Figure 2a it is not really possible to be sure how much distortion exists at the base of the 2T pulse whereas in Figure 2b where the signal has previously been passed through an FL4 557 lowpass filler of BBC design connected between AUX VIDEO OUT and AUX VIDEO IN it is clear that one would proceed with a measurement with much more confidence The improvement is even greater subjectively than appears from the photographs AUX VIDEO OUT IN 759 PICTURE MON OUT Figure 1 Block Schematic of Auxiliary Video Facility 3 30 REV A SEP 1980 a c_i b Signal after bani Figure 2 Improvement in Signal To Noise Ratio by Band Limitation The advantages of connecting the filter in the AUX VIDEO path are that it may be left in place as long as desired ready to be called up at the turn of a switch and that the distortion likely to be caused by connecting this type of filter between long coaxial cable lengths in a loop through circuit is eliminated by the good 759 terminations provided by the AUX VIDEO path Moreover lowpass filters of this type have a considerable time delay in this instance 500 ns as can be seen by comparing Figures 2a and 2b Any possibility of timing errors from such a
53. 00 nsec div time bases using the convenient NTSC color burst Also located on the 0 IRE Unit horizontal reference line are points T and B Point T is for use in measuring rise and fall time It lies directly below point R and denotes the time zero when the 90 point of a 100 IRE Unit rising transient or 10 of a 100 IRE Unil falling transient intersects point R at the 80 IRE Unit line If there is any serious tilt of the blanking level there is ambiguity in the selling of the blanking level to the 0 IRE reference level To remove that ambiguity a study group of the CCIR CMTT 187 E has recommended that insertion gain be measured between the center of the white bar and a blanking level reference point On Graticule A this blanking level reference point is labeled B Internal and External Graticules Two graticules are installed in each 1480 Selective illumination of either graticule allows the user to in effect choose the appropriate graticule for his measure ment Parallax errors are entirely avoided when an internal gralicule is used The external graticule however is subject to parallax error This error can be elimi nated when taking waveform photo graphs by using an external graticule designed to correct for parallax Tek tronix provides such graticules and strongly recommends them for wave form photography Labeled Photographic they should only be used for waveform photography because they are designed
54. 08 Cable TEKTRONIX Overseas Distributors in over 40 Countries REV A SEP 1980 3 39 Application Notes 1480 Series SN B060000 up Tektronix COMMITTED TO EXCELLENCE USING THE 1480 SERIES WAVEFORM MONITOR television application note no 21 All Fields Display to Improve NTSC In Service Testing by John Lauer Since their introduction the use of Vertical Interval Test Signals for in service measurements has revolutionized tele vision transmission system measurement techniques For the first time it became possible to comprehensively assess distortions caused by the transmission system while the system was in use To further these techniques a feature that permits for example the simultaneous display of VITS occuring on all fields has been incorporated in the 1480 Series Waveform Monitor In instruments of this series designed for use on PAL where four pushbuttons uniquely select the four fields of the PAL signal a separate push button selected function labeled ALL FIELDS is provided Instruments designed for NTSC on the other hand will have two field selection pushbuttons and when both are depressed the display is selected This new display mode presents three distinct advantages 1 Simultaneous viewing of VITS 2 Transmission system analysis through comparison of VITS inserted at separate points 3 A novel in service field time distortion measurement tech nique Other useful applications of this new and ve
55. 1 5 2 19 1 5 dB Attenuator Must be constructed by customer as shown below o 2338 92 75 Q 1 5 dB Attenuators PROCEDURE 1 Check Astigmatism a Connect the video signal source to the 1480 Series Video INPUT A Connector and terminate the loop through connector into 75 Q See Figure 5 1 b Set the INTENSITY control to about 2 o clock and adjust the front panel FOCUS control for a sharp well defined display VIDEO SIGNAL SOURCE Composite Video 750 TERMINATION 1480 SERIES 2338 23 Fig 5 1 Initial connections for 1480 Series performance check REV A SEP 1980 2 Check Magnified Tracking a Alternately press the LINE SELECTOR OFF and DIG pushbuttons without readjusting FOCUS or INTEN SITY Check that the display maintains its definition and brightness Intensification and Focus b Press the LINE SELECTOR OFF pushbutton c Rotate the MAGNIFIER switch throughout its range and check that the display maintains its brightness over the MAGNIFIER range 3 Check Geometry and Trace Rotation a Set the INPUT selector to B DC CPL Dand position the trace to the graticule center line 0 5 V or 40 IRE b Check that the trace is level with the center graticule line If not adjust TRACE ROTATION so that the trace is level with the center graticule line c Check that the trace is approximately level with the top and bottom graticule lines 4 Check Y Axis Alignment a Ch
56. 116 429 432 13 02 871 1190 398 Ri Ki Ro R Kr Ro SYMMETRICAL T PAD Kim R2 K Ro Rs Ks Ro SYMMETRICAL T PAD QA TM Ru AiL Kat fgg Dein DEA ASYMMETRICAL PAD must be terminaled as shown A 1 A Ks A INSERTION VOLTAGE RATIO ANTILOG 0 05 dB LOSS Figure 5 Design of Attenuator Pads Copyright 1974 Tektronix Inc All rights reserved Printed in U S A Foreign and U SA Products of Tektronix Inc are covered by Foreign and U S A Palents and or Patents Pending Information in this publication supersedes all previously published material Specification and price change privileges reserved TEKTRONIX SCOPE MOBILE TELEQUIPMENT and are registered trademarks of Tektronix Inc P O Box 500 Beaverlon Oregon 97005 Phone Area Code 503 644 0161 Telex 36 0485 Cable TEKTRONIX Overseas Distributors in over 40 Countries 9 74 REV A SEP 1980 AX 3079 3 33 Application Notes 1480 Series SN B060000 up TEKTRONIX technical excellence U rrr J LANTIY u A NEW NTSC GRATICULE FOR THE 1480 WAVEFORM MONITOR Operational Measurements Using a New NTSC Composite Graticule By Charles W Rhodes and John Lauer The modern display features of ihe TEKTRONIX 1480 Waveform Monitor have been further enhanced by a new versatile NTSC graticule Many linear transmission distortion measuremenls that have been difficult or inconvenient can now be made with rela
57. 15 Check LOW PASS Filter a Press the CAL and DC RESTORE SYNC TIP pushbuttons b Set the RESPONSE switch to LOW PASS c Check the corner of the leading edge of the calibrator square wave for 0 5 5 mV or 0 7 IRE or less overshoot or ringing 16 Check DIFF D STEP Filter a Connect the video signal source composite video output to the 1480 Series VIDEO INPUT A connector and terminate the loop thru connector in 75 Q REV B SEP 1980 b Set the RESPONSE switch to DIFF D STEP and press the OPER pushbutton c Set the video signal source for a five step staircase modulated with 140 mV or 20 IRE of subcarrier d Check the amplitude of the differential step risers 5X normal The differentiated pulses should have 1 or less preshoot overshoot and ringing e Disconnect the composite video and connect the subcarrier from the video signal source to the 1480 Series instrument f Check that the displayed subcarrier is 20 mV or 2 8 IRE or less 17 Check 3 58 MHz Bandpass Filter if used a Connect the video signal source color bar signal to the 1480 Series VIDEO INPUT A connector and terminate the loop thru connector in 75 Q b Set the VOLTS FULL SCALE AND VOLTS FULL SCALE VAR so that the red bar is 100 IRE in amplitude See Fig 5 4 c Set RESPONSE to 3 58 BANDPASS 120 pres GRAT A 100 i 60 40 Fig 5 4 Red Color Bar with amplitude increased to 100 IRE NTSC Performance Verification
58. 1813 68 Displays the record current signal in Displays line by line chrominance the control track head in the record error Signal d mode 1813 69 Fig 2 11 TR70C operating waveforms cont 2 16 e Operating Instructions 1480 Series SN B060000 up PUSHBUTTON 1480 Series DISPLAY servo system that indicates lockup of 1813 76 TR 70C i PUSHBUTTON 1480 Series DISPLAY GUIDE zm CU LL a Displays a signal from the guide servo system as a performance check for that 1813 73 system Displays a signal from the capstan the system either in record or playback mode Displays the reference pulse as an Displays the tonewheel pulse as an operational check of the reference operational check of the tonewheel generator processor acer es BPs Displays a signal from the head wheel servo system that indicates lockup of the system either in record or playback 813 75 mode Fig 2 12 TR70C operating waveforms cont 2 17 Section 3 1480 Series SN B060000 up APPLICATION NOTES Information contained in this section is of a specific nature and goes far beyond normal Operating Instruc tions In some cases the information is new and has been added to this manual to keep it current Whenever new information concerning the operation of this ins
59. 1C PAL Waveform Monitor 1481R PAL Waveform Monitor 1482C PAL M Waveform Monitor 1482R PAL M Waveform Monitor 1485C PAL NTSC Dual Standard Waveform Monitor 1485R PAL NTSC Dual Standard Wavelorm Monilor Option 1 1 megohm 20 pf probe input probe not included Suggested Probe P6065A 10X Probe 6 ft Order 010 6065 13 9 ft Order 010 6105 05 Option 2 With carrying Case Cabinet Version Only Option 3 With Blank CRT TEKTRONIX Automatic Correction Products are also available for 525 60 NTSC systems TEKTRONIX committed to fechneat escellence P O Box 500 Beaverton Oregon 97077 US A 3 29 Application Notes 1480 Series SN B060000 up application notes TEKTROND C committed to technical excellence TIONAL a no 17 The Auxiliary Video Facility of the 1480 Series of Waveform Monitors by L E Weaver Tektronix European TV Engineering Consultant The AUXILIARY VIDEO facility of the 1480 Series of Waveform Monitors is a novel and imaginative feature whose inclusion indicates the care taken during the planning of these instru ments to ensure the greatest flexibility of use combined with ease of operation and a degree of protection against obsoles cence lis primary funclion is to make possible a wide range of signal processing facilities in a side chain which can be switched in or oul without impairing the normal use of the instrument As can be seen from the schematic diagram Figure 1
60. 5 Figure 3 K ph K To measure pulse to bar ratio place ihe composite tesi signal bar leading edge over the ascending arrow and the blanking level on the 0 IRE Unit reference line at point B If insertion gain is incor rect bar midpoint not at 100 IRE use the 1480 VARiable VOLTS FULL SCALE 1o correct this condition The pulse to bar measurement is from bar midpoint to peak 2T pulse amplitude expressed in or percent See Figure 3 K If insertion gain is incorrect adjust the VARiable VOLTS FULL SCALE to compensate Use a 200 nsec div time base and posilion the 2T pulse beneath the Ka scale This measurement uses Graticule B To illuminate the external Graticule B pull the Scale Illumination knob See Figure 4 The mask corresponds io 5 If greater resolution is desired change the VOLTS FULL SCALE without moving VARiable to 0 5 for 2 2 or 0 2 for 1 mask limits See Figure 5 m GRAT B Figure 5 K measurement with increased gain K gt 1 Short Time Waveform Distortion SD IEEE Trial Slandard 511 1974 describes ihe technique for measuring short time waveform distortion SD in detail Graticule B includes the mask prescribed in the Trial Standard The 1480 s POSI TION controls are adjusted so that the transition passes through points B blanking and C and the vertical gain is set so that white level of the bar passes through point W Some control interac tion will take place
61. 75 Tektronix Inc All rights reserved Printed in U S A 3 20 REV A SEP 1980 The Monitor and the VTR Figure 2 shows the interconnections for routine operation and maintenance of a broadcast videotape recorder The video signal is provided to the Waveform Monitor from a signal selector panel in the VTR The Waveform Monitor displays this signal and also provides a unique video signal to a picture monitor In any of the line selector modes digital variable or 15 line the lines being displayed on the Waveform Monitor appear intensified on the picture monitor In the 2 field mode of the Waveform Monitor these selected lines are displayed as an intensified portion of the sweep as shown in Figure 3 This is an excellent way to exactly locate the lines of interest within a picture Select the desired mode and simply adjust the VARIABLE LINE SELECTOR control until the lines of interest are intensified and those will be the lines displayed when the time base is changed to give a one or two line display The picture monitor always shows those intensified lines being displayed on the Waveform Monitor independent of the horizontal sweep mode of the Waveform Monitor WAVEFORM MONITOR PIX MON OUT PICTURE MONITOR Figure 2 Equipment setup for normal VTR operation and maintenance Figure 3 Two field display with selected lines intensified In a quadruplex videotape recorder each head pass covers just a bit more than 15 lines
62. 75 kHz will not permit anormal TV display Sync Jitter with composite video or composite sync 12 ns maximum jitter With respect to input sync With up to 4 V rms hum with variable APL 10 90 20 ns maximum jitter With up to 4 V rms hum With variable APL 10 90 36 dB white noise 90 ns maximum jitter With up to 4 V rms hum AFC SYNC Horizontal Frequency Range 15 75 kHz 200 Hz Lock In Time Less than 1 second Sync Jitter with composite video or composite sync 10 ns maximum jitter With respect to input sync With up to 4 V rms hum with variable APL 10 9096 12 ns maximum jitter With up to 4 V rms hum with variable APL 10 90 36 dB white noise 30 ns maximum jitter With up to 4 V rms hum Jitter with respect to white noise Jitter doubles with each 6 dB increase in white noise Noise Immunity DIRECT Less than 250 ns jitter with 1 V composite video plus 26 dB white noise AFC Less than 90 ns jitter with 1 V composite video plus 26 dB white noise 4 6 REV A MAY 1980 Specification 1480 Series SN B060000 up Table 4 3 cont Characteristic Performance Requirement Supplement Information Jitter from missing line sync pulses Less than 15 ns per missing sync pulse Maximum of 10 consecutive line sync pulses 50 60 Hz Recognition Automatic for dual standard m
63. Alters vertical gain allowing 1 0 0 5 or 0 2 volt signals to produce full screen deflec tion Also acts as a vertical magnifier providing X2 or X5 expansion of the input signal 6 VAR VOLTS FULL SCALE Varies vertical gain from X0 5 to X1 4 nominal 6 dB to 3 dB when not in the CAL detent position 7 UNCAL Lights up to indicate the VAR VOLTS FULL SCALE control is not in CAL 8 RESPONSE Selects wide band filtered or differentiated vertical response modes Also selects aux iliary video input from rear panel LOW PASS Attenuates frequencies 500 kHz and up by at least 14 dB 40 dB at 1 MHz typical IRE Conforms to IRE standard 23S A 1958 22 dB at 4 43 MHz typical 1480C and 1480R only FLAT Unfiltered wide band position Flat to 5 MHz or more 3 at 10 MHz 4 48 BANDPASS Provides bell shaped response curve with 4 43 MHz as center frequency Within 196 of FLAT reference at 4 43 MHz 3 58 BANDPASS Provides bell shaped response curve with 3 58 MHz as center frequency Within 196 of FLAT reference at 3 58 MHz DIFF D STEP Differentiates risers of linearity test signals providing amplitude comparisons of staircase step risers Automatically increases vertical gain to maximum between 5 and 7 times Attenuation in creases from about 2 dB at 0 5 MHz to about 40 dB at color subcarrier center frequencies Dc restoration not effective in this mode AUX VIDEO IN Provides unfiltered wide ban
64. DS mode center two buttons pressed with DISPLAY in 5 us DIV or 10 us DIV and the LINE SELECTOR VAR pressed no display will be ob tained if the LINE SELECTOR VAR potentiometer is set to display lines during the time a second field would have been displayed The ALL FIELDS mode time overlays each successive field on the first half of the 2 FIELD display thus the maximum ramp amplitude at the 2 Field Sweep Generator is 5 volts The LINE SELECTOR VAR control has a range of 0 to 10 volts at the input to the 2 Field Sweep Generator Since the LINE SELECTOR VAR control voltage is applied to one side of a comparator in the 2 Field Sweep Generator device there is no delayed gate output if the LINE SELECTOR VAR is set above the maximum ramp voltage 5 volts 2 The four front panel FIELD buttons would seem to imply that the 1480 Series monitors identify four fields of any television system In PAL systems the Bruch se quence certainly identifies four fields but NTSC and PAL without Bruch sequence systems have four less clearly identified fields These fields are determined by subcarrier phase with respect to the leading edge of line sync The 1480 Series monitors positively identify four PAL fields in the presence of the Bruch sequence but cannot identify fields that are different from each other only in the phase of the subcarrier with respect to line sync 3 If composite PAL video isapplied to the AUX VIDEO IN connector and composite syn
65. IX SCOPE MOBILE TELEQUIPMENT and are registered lrademarks of Tektronix Inc P O Box 500 Beaverlon Oregon 97077 Phone Area Code 503 644 0161 TWX 910 467 8708 Cable TEKTRONIX Overseas Distribulors in over 40 Countries 6 75 REV A SEP 1980 AX 3077 1 3 25 Application Notes 1480 Series SN B060000 up application notes Tektronix COMMITTED TO EXCELLENCE U uUUUUUUUUUUUUULUUUUUUU UUUUUNU no 16 Verifying the Bruch Blanking Sequence Verification of the Bruch blanking sequence falls into the area of routine testing and though necessary is tedious Using the accurate four field selection of a 1480 Series Waveform Monitor can reduce the time required for this test In essence only 4 lines need to be observed to accurately determine if the se quence is occurring correctly on each field Figure 1 shows the PAL Bruch blanking sequence and identifies lines 6 310 319 and 623 If the Bruch blanking sequence for PAL M 525 60 used in Brazil is being verified using a PAL M 1480 Series Waveform Monitor disregard Figure 1 Lines 8 259 270 and 522 will be substituted for those above Table 1 in the Verifica tion Procedure is prepared for both 625 50 PAL and 525 60 PAL M The Verification Procedure that follows displays portions of two Figure 2 fields The first field whose sync triggers the time base cor responds to the field selected by front panel pushbutton The investigation of the blanking seq
66. MONITOR OUT 1 0 02 VARIABLE VOLTS FULL SCALE RANGE Input signals between 0 7 volts and 20 volts can be adjusted 1o 1 voll equivalent display height Maximum Input Signal for inspecification op eration of AUX VIDEO OUT and PIX OUT AC CPL D INPUT A and B 2 0 V P P at any APL Display distortion 10 V P P at any APL if both AUX VIDEO OUT and PIX OUT are terminated for distortion free signal al those outputs DC CPL D INPUT A and B 15 V DC Peak AC AUX VIDEO IN 15 V DC Peak AC Maximum Output DC Voltage AUX VIDEO OUT and PIX MONITOR OUT into 75 9 0 5 V DC Common Mode Rejection Ratio A B 60 Hz gt gt 46 dB 15 kHz gt 46 dB 4 43 MHz gt gt 34 dB Frequency Response FLAT including INPUT A or INPUT B Through AUX VIDEO OUT or PIX MONITOR OUT from 50 kHz Reference 50 kHz lo 5 MHz 0 5 5 MHz to 10 MHz 0 5 3 IRE Conforms lo IRE 1958 slandard 238 1 Altenuation al 4 43 MHz gt 22 dB LOW PASS Attenuation gt 14 dB 500 kHz and above 3 58 MHz 1 of FLAT at 3 58 MHz 3 dB down at 3 1 to 3 4 MHz and 38 lo 4 0 MHz 443 MHz 1 of FLAT al 4 43 MHz 3 dB down at 3 9 to 4 1 MHz and 4 7 to 4 9 MHz DIFF D STEPS Per mits amplilude comparisons of risers on stair step signal with automalic gain increase of 5 times attenuation 7 2 dB from 0 4 lo 05 MHz attenuation 7 20 dB al 15 kHz and 2 MHz at tenuation gt 40 dB at 3 58 MHz and 4 43 MHz Linear Waveform Distortion Pulse Presho
67. Megohm 2 20 us 0 5 Not including probe Not including probe GAIN Range 10 Adjustable for 1 volt peak to peak display amplitude Gain Unity 3 with GAIN adjusted for equivalent 1 volt peak to peak display Frequency Response 25 Hz to 5 MHz 2 Referenced to 50 kHz 5 MHz to 10 MHz 3 5 Tilt Less than 5 on 50 Hz squarewave FAST DC RESTORER eliminates low frequency tilt on a composite video signal Non Linear Distortion differential gain Less than 0 25 any APL differential phase Less than 0 25 any APL Probe Calibrator waveform Squarewave duty cycle 50 period 4 horizontal lines output voltage 1 000 V 0 5 0 995 V to 1 005 V output impedance Approximately 950 ohms REV B SEP 1980 4 5 Specification 1480 Series SN B060000 up Table 4 3 SYNCHRONIZATION Standard Instruments Characteristic Performance Requirement Supplemental Information SYNC Input INTernal 200 mV to 2 V peak to peak Composite video applied composite video to Aor B VIDEO INPUT EXTernal composite video 400 mV to 2 V peak to peak composite video Composite video applied to EXTERNAL SYNC Input composite sync 200 mV to 8 V peak to peak composite sync Composite sync applied to EXTERNAL SYNC Input DIRECT SYNC Horizontal Frequency Range Up to 20 kHz Frequencies much below 15
68. NC TIP to BACK PORCH This not only alters the clamping mode but at the same time brings in a square wave whose amplitude is 700 mV for 625 line signals or 714 mV for 525 line signals With dual standard instruments the changeover is effected automatically when either the internal or the external graticule is brought into use by actuating the SCALE ILLUM control The procedure is exactly the same in principle as that used for the overall amplitude and the same remarks apply with the exception that the use of the overlay facility is less advan tageous as can be seen from the photographs Figures 7a 7b Top of bar continuous with black level Figure 7b As Figure 7a but level 10 high REV A SEP 1980 The sync pulse amplitude is not measurable directly by this method but of course it is available by subtracting the picture amplitude from the overall Comments This method of setting and measuring the level of video signals has the great advantages of absence both of parallax and of the transfer error associated with the conventional method To understand what this latter means consider how such a measurement is most usually carried out A calibrating square wave is first displayed and the vertical gain is adjusted until it appears to fit as well as possible between two fixed graticule lines The square wave is then removed and the video wave form displayed and compared against the same pair of refer ence lines Several
69. R A confusing display for accurate measurements Slight alteration of the 520 Series Vectorscope is required to use the 1480 Series Waveform Monitor strobe output to un blank the lines of interest In addition a pair of signal diodes will need to be added to the PAL or PAL M 520 Series Vectorscope to retain PAL blanking To modify the Vectorscope except 520s below serial number B15000 for unblanking by the strobe output of the 1480 Series Waveform Monitor move the coax cable from pin BO of the sweep circuit board to pin BQ For 520s below serial number B15000 only move the coax cable from pin AR of the sweep circuit board to pin AW Install the signal diodes in either 521 521A or 522 522A Vectorscopes as REV A SEP 1980 Application Notes 1480 Series SN B060000 up follows Place one anode to coax cable between pin BR of the sweep circuit board and the coax cable connected lo it The second again anode to coax cable between pin BQ and the coax cable that has been moved to it If V V identification is not needed disconnect the coax cable from pin BR and skip installing the diodes Figure 12 shows the equipment hook up for differential gain and phase measurements STROBE OUTPUT D VECTORSCOPE Figure 12 Equipment connections for differential gain and phase measurements For this measurement record several minutes of modulated stairstep or ramp on the recorder and rewind On playback locate the head of
70. RLAY Time overlays that portion of the sweep occuring after the break point with the preceding part of the sweep As the control is rotated coun terclockwise the display will overlay from right to left A red indicator turns on when the OVERLAY control is active 24 INTENSITY amp FOCUS Control brightness of the beam and definition of the display 25 SCALE ILLUM Adjusts illumination of the inter nal or external graticule markings PULL FOR EXT Selects lighting system for external graticules and turns off internal graticule system It also selects the calibrator waveform amplitude for the BACK PORCH mode of the DC RESTORER The external graticule restrains a slide switch at its base behind the bezel to selecting the appropriate calibra tion voltage CONNECTORS The following is a discussion of the various input and output connectors In addition there are other features that are incorporated in the rear panel configuration they too are discussed here All items mentioned are found in Fig 2 3 27 VIDEO INPUTS A amp B High impedance loop thru inputs for composite video Compensated for 75 Q not internally terminated REV A MAY 1980 Operating Instructions 1480 Series SN B060000 up 3 23 3 1 V Fig 2 3 Rear panel connectors and features for 1480 Series rackmount and cabinet models Operating Instructions 1480 Series SN B060000 up 28 EXTERNAL SYNC A amp B High impe
71. Tektronix Inc P O Box 500 Beaverton Oregon 070 2338 00 97077 Tektronix COMMITTED TO EXCELLENCE 1480 SERIES WAVEFORM MONITORS B060000 and above INSTRUCTION MANUAL Serial Number B 67S 2 2 0 First Printing MAY 1977 SUE Y mission o in U S A Specification and price change S are ed 1480 Series SN B060000 up SAFETY SUMMARY The following are general safety precautions that must be observed during all phases of operation WARNING information in this manual is intended to protect personnel from hazardous primary voltages CAUTION information is intended to protect the instru ment from damage Electrical shock hazards are present inside this instrument Only qualified service per sonnel should remove the instrument cover To reduce the electrical shock hazard the instrument chassis must be properly ground ed Refer to Section 1 Unpacking and In coming Inspection The crt used in the 1480 Series Waveform Monitor is a high vacuum device and should be handled with care Be sure to read the war nings and procedure for crt replacement in SECTION 7 before attempting to remove the crt Avoid coming in contact with components that are operating at high temperatures such as high wattage resistors spaced above the cir cuit boards power transistors some of the metal can transistors and some of the in tegrated circuits IC Handle silicon grease with care Avoid getti
72. ULL SCALE for a pulse amplitude of 100 IRE Units Shift the pulse down until the peak is at ihe 50 IRE Unit line See Figure 13 The Graticule 0 IRE Unit reference line now intersects the pulse at the half amplitude point Figure 13 Half amplitude Duration H A D measurement of a 2T pulse H A D 245nsec By selecting the proper time base the half amplitude duration HAD of the pulse is directly measured on the 0 IRE Unit reference line Use a 100 nsec div time base for a T or 2T pulse and a 500 nsec div time base for a 12 5T modu lated sine squared pulse Sync Amplitude Sync amplitude error can be read directly using the scale at the center of the 40 IRE Unit graticule line This scale is marked at 36 38 40 42 and 44 Units or 10 5 096 4 595 and 1096 respeclively It is located in time so that it can be used with either the 10 zs DIV or 2 FIELD Figure 14a Horizontal line Sync Ampli tude measurement Sync Amplitude 40 IRE 20 CRAT A Figure 14b Vertical field Sync Ampli tude measurement Sync Amplitude 40 IRE Vertically place the blanking level of the composite video waveform on the grati cule s 0 IRE Unit reference line Check insertion gain and then read horizontal sync amplitude using the 10 us DIV time base Figure 14a or vertical sync amplitude using the 2 FIELD DISPLAY Figure 14b Tests With Other Signals Amplitude Vers
73. Using the 200 nsec div time base an undistorted 1T transi tion will lie perfectly centered in the mask See Figure 6 Figure 6 S D using 2T pulse rising tran sient S D 2 The FCC Composite VITS 873 699 Figure 15 provides for a 2T bar This signal cannot be used to measure SD It does however include a 2T pulse which 3 35 Application Notes 1480 Series SN B060000 up may be used to measure SD using the 2T pulse mask of Graticule B See Figure 4 A 5 value of SD is used as the basis of the mask in Graticule B again this is in conformity with the IEEE Trial Standard 511 1974 In a linear system one need only mea Sure one transition rising or falling but in practical circuits non linear distor tions may affect the transitions very differently This provides a clue to the presence of such non linear distortions It is good therefore to measure both transitions Each might be characterized by a different value of SD Chrominance Luminance Gain Inequality Check insertion gain If it is not unity use the VARiable VOLTS FULL SCALE to get a 100 IRE Unit blanking to bar center amplitude Use a 1 s DIV time base and check the peak amplitude and base line offset of the 12 5T modulated sine squared pulse If other forms of distor lion are not present the variation in peak amplitude and the baseline offset at pulse center will be equal See Figure 7 Figure 7 Chrominance to Luminance G
74. ain Inequality measurement C L Gain Inequality 9 6 Assuming that the 12 5T pulse baseline is symmetrical negligible chrominance luminance delay as shown in Figure 7 gain inequality can be measured using either the vernier scale 10 to 10 IRE or the R scale to the right of the pulse Each division of these scales equals 2 IRE Units Chrominance lumi nance chrominance to luminance gain inequality is equal to twice the difference between 100 IRE Units and peak dis played amplitude of the 12 5T modulated sine squared pulse expressed in per centage This measurement can also be made by using a TEKTRONIX 1478 Calibrated Chrominance Level Corrector in the 1480 Aux Video Out Aux Video In 3 36 configuration See Television Applica tion Note 17 The Auxiliary Video Facility of the 1480 Series of Waveform Monitors by L E Weaver Chrominance Luminance Delay If the chrominance luminance gain in equality is negligible or has been annulled for example using the TEK TRONIX 1478 Calibrated Chrominance Level Corrector See Television Prod ucts Application Note 10 Chromi nance to Luminance Gain Correction and Delay Measurements chrominance luminance delay inequality can be read directly from Graticule A Use a 1 4s DIV time base and hori zontally center the 12 5T modulated sine squared pulse Set displayed pulse amplitude for 100 IRE Units blanking level to pulse peak amplit
75. an 50 Hz to more than 60 Hz Signal A 50 to 60 Hz squarewave with no field sync and filtered line sync Sensitivity 400 mV peak to peak min to 3 V peak to peak max Input Impedance Approximately 10 kilohm ac coupled Input Acquisition f Rear panel AUXiliary SYNC loop thru input connector Actuation Simultaneous use of the INTernal and EXTernal SYNC switches Table 4 6 HORIZONTAL SYSTEM Characteristic Performance Requirement Supplemental Information Sweep Timing Accuracy 5 us DIVision 2 center 10 divisions 10 us DIVision 2 center 10 divisions 2 FIELD Proportional to the line rate sweeps 5 and 10 us division Linearity 5 us DIVision 1 10 uS DIVision 1 2 FIELD 0 5 division SLOW SWEEP Option 7 5 of full screen over the length of the sweep Magnified Sweep Timing Accuracy X5 1 us DIV Center 10 div of unmagnified sweep 1 Calibrated at 1 us DIV X10 0 5 us DIV 2 X20 0 25 us DIV 3 X25 0 2 us DIV 3 X50 0 1 us DIV 3 Linearity X5 1 us DIV 2 X10 0 5 us DIV 2 X20 0 25 us DIV 2 X25 0 2 us DIV 2 X50 0 1 us DIV 2 REV A SEP 1980 Specification 1480 Series SN B060000 up Table 4 6 cont Characteristic Performance Requirement Supplemental Information VARiable MAGNIFIER 1481 1482 a
76. and the trace is not on the screen a red indicator lamp that is part of the Waveform Comparison circuit will be lit 17 MAG gs DIV Overrides DISPLAY switch to select other sweep deflection factors Display brightness is automatically increased to maintain balanced displays OFF Selects normal sweep modes controlled by DISPLAY switch X5 X10 X20 X25 X50 Magnifies 2 FIELD and EXTernal displays accordingly 1 5 25 2 1 Overrides 10 us DIV or 5 us DIV modes to provide indicated calibrated sweep speeds VAR 1481 1482 and 1485 only Extends the effective range of the fixed magnifier positions REV B MAY 1980 18 HORIZONTAL POSITION Moves display horizontally with a ten turn potentiometer This has sufficient range to display both ends of the sweep at 50 times magnification 19 FIELD Positively selects the beginning of the 2 FIELD sweep Buttons select individual fields 1 2 3 or 4 for PAL systems or EVEN fields 1 and 3 or ODD fields 2 and 4 field pairs for NTSC systems HORIZONT POSITION A Right front section rackmount model Operating Instructions 1480 Series SN B060000 up Simultaneously pressing FIELD 3 and 2 buttons and any LINE SELECTOR function selects all fields to be time overlaid During the ALL FIELDS mode the horizontal sweep is only one field period long The LINE SELECTOR VARiable control cannot be used to select lines or groups of lines that belong in the sec
77. ange the INPUT selector to A DC CPL D and set the VOLTS FULL SCALE selector to 0 2 Vertically posi tion the display so that only the rising and falling portions of the display are visible b Use the HORIZONTAL POSITION control to posi tion the vertical lines across the crt screen Check that the vertical lines are perpendicular to the bottom graticule line 5 Check Vertical Gain Out A VIDEO INPUT to AUX VIDEO OUT a Connect the video signal source and test os cilloscope as shown in Fig 5 2 b Set the test oscilloscope to 20 mV Div differential input with ac coupling Shut off the test generator chrominance c Check the display on the test oscilloscope for 5 mV or less amplitude excluding transitional spikes Performance Verification 1480 Series SN B060000 up 6 Check PIX MONITOR OUT Gain a Change the output cable from the AUX VIDEO OUT connector to the PIX MONITOR OUT connector b Check for a display amplitude of 20 mV or less excluding transitional spikes 7 Set Front Panel Gain Adjustment a Press the DC RESTORER SYNC TIP and CAL pushbuttons b Check for 1 volt equivalent display height c Adjust GAIN control if necessary for 1 volt equivalent display height VIDEO SIGNAL SOURCE Composite Video 750 TERMINATION 75 Q TERMINATION 1480 SERIES Fig 5 2 Setup for 1480 Series Gain Measurement 5 3 Performance Verification 1480 Series SN B060000 up 8 Check A
78. arious subcarrier boosts are shown in Table for both 3 58 MHz and 4 43 MHz A video test signal generator providing a good sine squared pulse and bar signal such as the TEKTRONIX 148 for example is then connected to the point where the video signal is nor mally applied and a suitable display of the chrominance pulse 20T 12 5T or 10T obtained on the waveform monitor Initially with a resistor alone in the series arm the baseline of the pulse will appear concave but as the capacitance is increased from zero this decreases until a point is reached where the baseline is as flat as in the input pulse Multiplying this critical value by two gives the series arm capacitance of the constant resistance equaliser The element values for the final equaliser can be calculated or taken from Table I With these small values of correction its construction presents no real difficulties The required capaci tance can be synthesised by connecting values in parallel and the inductance value can often be found to a sufficient accuracy in a series of commercial miniature wire ended chokes AUX VIDEO IN o __ AUX VIDEO OUT o 28 30 AUX VIDEO IN o _ AUX VIDEO OUT o 1989 0 o _ 752 397 92 L 757C Figure 4 Conversion of 2 Terminal Networks to the Equivalent Constant Resistance Equaliser REV A SEP 1980 The final step is to connect the equaliser in series with the waveform monitor an
79. arker is provided whenever the circuit is REV A SEP 1980 z xs 13 32512 19232 aam 20333 10 25 x3 g 322 x0 Li Application Notes 1480 Series SN B060000 up HORIZONTAL POSITION WAVEFORM COMPARISON LOCATE 5 OVERLAY UNE SELECTOR ko cta UN C 32 operating Figure 4 shows the marker which is controlled by the LOCATE control The other inner control knob labeled OVERLAY moves the portion of the waveform to the right of the intensity marker For example the line bar lies to the left of the sine pulse as shown in Figure 4 but the sine pulse is easily moved to the left for comparison with the bar which remains stationary Once the sine pulse is positioned at bar midpoint very small differences in pulse and bar amplitudes can be resolved by 3 13 Application Notes 1480 Series SN B060000 up Figure 4 magnifying the signal vertically For example a 1 difference in 2T pulse to bar ratio equals 1 IRE unit 7 mV CCIR in a 1 volt full scale deflection This is barely discernible but with X5 vertical expansion a 1 pulse to bar amplitude in equality is displayed as a difference of 5 IRE units as shown in Figure 5 A 1 difference in pulse to bar amplitudes is approximately K 0 25 If a Ky of 0 25 can be dis played as 5 IRE units then one may easily resolve K to say 0 1 K For a measurement of chrominance luminance gain inequality a modulated sine pul
80. at the factory to ensure that the instrument will continue to meet these Performance Requirements Table 4 1 VERTICAL SYSTEM Characteristic Performance Requirement Supplemental Information Input Impedance 75 ohms nominal Auxiliary Video Input Vertical Ranges Display VOLTS FULL SCALE NTSC CCIR 1 0 140 IRE 10096 0 5 140 IRE 100 0 2 140 IRE 100 Vertical Accuracy VOLTS FULL SCALE 1 0 7 mV 0 5 15 mV 0 2 7 mV Any one range may be ad justed to unity However the accuracy of the others may not remain within the Performance Requirement Input Gain Ratios Ato B 1 to 1 0 002 0 998 1 002 AUXiliary VIDEO INput to INPUT A 1 5 dB 0 3 dB INPUT A to AUXiliary VIDEO OUTput 1 to 1 0 005 0 995 1 005 Adjustable INPUT A to PIX MONITOR OUTput 1 to 1 0 02 0 98 1 02 REV B FEB 1980 Specification 1480 Series SN B060000 up Table 4 1 cont Characteristic Performance Requirement Supplemental Information Maximum Input Signal Ac coupled INPUT A and B 2 0 V peak to peak at any average picture level 1 0 V peak to peak at any average picture level with both AUXiliary VIDEO OUTput and PIX MONITOR OUTput terminated Maximum dc component 5V Dc coupled INPUT A and B and AUXiliary VIDEO INput 1 5 V dc peak ac Maximum voltage from Loop Thru common terminal to chassis in Floating Ground mode 4 Vrms at mains
81. ay allow the metal parts of this instrument to be elevated above ground potential and create a shock hazard Damage Inspection After carefully removing the 1480 Series Waveform Monitor from the shipping carton inspect the instrument for possible damage incurred during shipment Report any shortage or damage to the carrier Save the shipping carton and packing material in case you need it to repackage the instrument for shipment Included Accessories List A complete listing of accessory items that are shipped with the various 1480 Series models can be found follow ing the Replaceable Mechanical Parts list near the rear of this manual The graticule or scale items that follow are part of the listing under Standard Accessories They are also listed here as a convenience to the user The following crt scale is shipped with all 1480 Series Waveform Monitors Tektronix Qty Description Part No 1 Scale crt Blank 331 0393 00 The following graticules are supplied according to the 1480 Series configuration Tektronix Qty Description Part No 1 CCIR Composite 1481 1482 1485 Opt 3 amp 1485C Opt 5 331 0393 02 1 CCIR K Factor visual 1481 amp 1485 331 0393 05 Tektronix Qty Description Part No 1 CCIR K Factor photo 1481 amp 1485 except Opt 3 331 0393 07 1 NTSC Graticule A visual 1485 amp 1480 Opt 3 331 0393 08 1 NTSC Graticule B visual 1480 amp 1485 331 0393 09 1 NTSC Graticule A photo 1485 e
82. ble Connect the second SYNC connector through 50 Q cable and a 50 Q termination to the test oscilloscope vertical input b Connect composite video from the video signal source to the 1480 Series VIDEO INPUT A connector and terminate the loop thru connector in 75 Q 5 12 c Connect composite sync from the video signal source to the 1480 Series EXTERNAL SYNC A input connector and terminate the loop thru connector in 75 Q d Connect the 067 0621 00 Calibration Fixture to J9034 on the 1480 Series rear panel e Set the 1480 Series DC RESTORER selector to FAST BACK PORCH and SYNC to EXT Set all switches on the 067 0621 00 up Normal f Set the test oscilloscope Time Div to 0 5 ms and Volts Div to 5 Set the pulse generator output amplitude for 3 volts pulse duration for 300 us and period for 4 167 ms 4 ms for 625 line scanning system g Rotate the 1480 Series vertical POSITION control to set the back porch of the displayed signal at blanking level h Remove the 75 Q termination from the VIDEO INPUT A connector Check that the back porch of the displayed signal is clamped at blanking level Replace the termination i Set the 067 0621 00 Horizontal Display switch to 2 Field or Tone Wheel Check to see that the back porch of the displayed signal remains at the blanking level j Remove the termination from the VIDEO INPUT A connector Check to see that the back porch of the displayed signal is not clamped Replace the
83. c to the EXT SYNC IN connectors with no signal to the VIDEO INPUTS or with the INPUT switch in the PROBE position and SYNC in EXT the 1480 Series monitors will not positively identify the four PAL fields even in the presence of the Bruch sequence All the sync functions appear normal but the Frame Pulse Generator does not receive burst informa tion 4 Do not attempt to use the AUX VIDEO IN as an end of line termination for a signal looped through other instruments if the 1480 Series POWER switch is off With POWER on the AUX VIDEO IN circuit is internally terminated in 75 Q but with POWER off the impedance is around 80 Q 5 The additive calibrator mode where the front panel CAL and OPER buttons are pressed simultaneously operates only with the video signal connected to the A VIDEO INPUT If the INPUT switch is in B or PROBE the display in the additive calibrator mode will still be whatever is connected to the A VIDEO INPUT superim posed on the calibrator signal 6 With the INPUT switch in the PROBE position and the front panel CAL button pressed the DC Restorer is disabled and no clamping is done The DC Restorer operates with the OPER button pressed 7 The calibrator timing flipflop is disabled if the LINE SELECTOR 15 LINES button is pressed and the DISPLAY Switch is in 5 us DIV 2 FIELD or EXT 8 In PAL instruments the lack of Bruch sequence in the incoming video signal causes loss of sweep if FIELD 1 or FIELD 4 bu
84. cales One is used inthe NTSC countries and is referred to in this procedure as the NTSC graticule The other scaled for use with PAL standards is identified as the CCIR graticule The horizontal time scale is the same for both because the 1480 Series time base is in microseconds us rather than increments of line time The major difference lies in the vertical scales Oto 1 volt forthe CCIR graticule and 40 to 100 IRE for the NTSC graticule Where amplitude measurements are made in this procedure the results are given in both mV and IRE Through most of this procedure the instrument is operating in a 75 Q impedance system A 75 Q end line termination should be used on the open side of the loop thru connector pair when termination is required Front and rear panel control and connector names on the 1480 Series instrument under test are capitalized for example VOLTS FULL SCALE Control and connector names on test equipment have only the first letter capitalized for example Time Div TEST EQUIPMENT REQUIRED The test equipment listed here was used in preparing this procedure The measurement capabilities described are the minimum required to verify instrument perfor mance Each piece of test equipment is assumed to be operating within its stated specifications If alternative equipment is used it must meet or exceed these re quirements REV A SEP 1980 Some additional test equipment is required to check the performance o
85. ch contributing these distortions will at the downstream end provide a degraded picture Since these distortions are small on a per link basis they prove hard to measure without use of calibrated vertical expansion and time base foldback Together these features of TEKTRONIX 1480 Series Waveform Monitor provide state of the art mea surement capabilities for both laboratory and operational work Television Measurement Techniques by L E Weaver Peter Peregrinus Ltd 1971 3 14 Figure 5 Figure 6 Figure 7 Figure 8 Copyright 1977 Tektronix Inc All rights reserved Printed in U S A Foreign and USA Producls of Tektronix Inc are covered by Foreign and U S A Patents and or Patents Pending Information in this publication supersedes all previously published material Specification and price change privileges reserved TEKTRONIX TEK SCOPE MOBILE TELEQUIPMENT and Pare registered trademarks of Tektronix Inc PO Box 500 Beaverton Oregon 97077 Phone Area Code 503 644 0161 TWX 910 467 8708 Cable TEKTRONIX More than 50 Subsidiaries Distributors around the world 5 77 AX 3071 1 REV A SEP 1980 CHARACTERISTICS Application Notes 1480 Series SN B060000 up SCALE FACTOR INPUT A and B 10 Volts Full Screen 1 3 mV 0 5 Volts Full Screen 15 mV 0 2 V F Screen 6 mV Ratio INPUT A lo INPUT B 1 0 002 to 1 AUX VIDEO IN to INPUT A 15 03 dB GAIN INPUT A to AUX VIDEO OUT 1 0 005
86. cluded here are the Electrical Specifications for Options 1 4 5 and 7 Options 2 and 3 require no change in the Electrical Specification and Option 6 has its own supplemental manual The electrical characteristics that follow can be verified using the Performance Check Procedure in Section 5 ELECTRICAL CHARACTERISTICS The electrical performance requirements given here can only be achieved over an operating ambient temperature range of 0 C to 50 C after a warm up time of 20 minutes necessary for operating temperatures at or near 0 C In addition the Performance Requirements are only valid if the instrument is calibrated in an ambient temperature between 20 C and 30 C aftera minimum warm up time of 10 minutes Performance Requirements Performance Requirements listed in this section assure accurate instrument performance Where necessary they are specifically tested by the Performance Check Procedure found in Section 5 In many cases it is not necessary to check each individual requirement because assurance may be achieved in other ways In some areas certain levels of performance have been designed into this instrument and if not present other broader Performance Requirements will not be met In a few cases the equipment required is extremely expensive not readily available or the procedure necessary to verify performance is very exacting Under these circumstances lot sampling and repetitive testing is done
87. ctly the same manner Note that this measurement does not form part of the standard K rating method but it has been found useful in the Federal Republic of Germany and is at present under consideration by the CCIR3 REV A SEP 1980 Application Notes 1480 Series SN B060000 up Measurement of bar trail Figure 3 Part 4 Chrominance Luminance Gain and Delay Inequalities Control Settings MAG x5 1 us div Others As in Part 1 There are two ways of carrying out this measurement The first by far the most convenient and accurate utilizes a TEKTRONIX 1478 Calibrated Chrominance Level Corrector A The 1478 may be inserted directly in series with the video signal under test Alternatively an arrangement which is much to be preferred when in service measurements are to be carried out the 1478 is connected in the AUX VIDEO path It is then available simply by turning the RESPONSE conirol to AUX VIDEO IN withcut the need for breaking the signal feed How ever since this path has a gain of 1 5 dB to allow for the loss of passive networks which may be used there it will be neces sary to introduce a compensating loss in front of the 1478 Preferably ihis should take the form of a 75 9 1 5 dB loss pad but since all impedances are resistive even a shunt or series resistor will suffice if facilities are limited Values are given in the diagram The measurement then proceeds as follows 1300 6460 6460 4310 1 5 dB 75
88. ctly under the bar See Fig 1 6 i Return the OVERLAY control to the detented position 2338 06 Fig 1 7 Test Signals that can be found in the vertical interval a Line 17 International Test Signal Europe b Line 330 International Test Signal Europe c NTSC Composite Test Signal Line 17 Field 1 d NTSC Test Signal Line 17 Field 2 16 Unpacking and Incoming Inspection 1480 Series SN B060000 up 6 LINE SELECTOR These tests require that the operator know on what vertical interval lines the test signals VITS or ITS have been inserted a DIGital Push the DIG and correct FIELD buttons o wwc wow w ae a gt rotate the LINE SELECTOR switch until a line known to 50 carry a test signal is selected For example line 17 or 330 in hal d T the PAL color system Check that the test signal is correct for the field and line selected See Fig 1 7a through 17d b VARiable Depress the VAR pushbutton and rotate the VAR LINE SELECTOR through its range and check that both vertical interval and picture area line can be displayed c 15 LINES Push the 15 LINES button and rotate the VAR LINE SELECTOR from end to end and find a display that has picture information and vertical interval lines including test signals See Fig 1 8 d ALL FIELDS Push the DIG pushbutton and select line 17 17 amp 330 Depress the ALL FIELDS pair and observe overlayed test signals See Fig 1 9 2338 08 Fig 1 9 Al
89. d P4240 installed With these plugs in place the gain is set for RGB operation for YRGB operation they need to be removed Because these changes require removing protective covers they should only be done by a quailified technician using the instruc tions from Section 6 of this manual RGB YRGB STAIRCASE INPUT GROUND FOR RGB YRGB 1813 258 Fig 2 8 J9034 connections for RGB or YRGB operation 2 12 Fig 2 9 A three step RGB display B YRGB display note 4 steps Using PIX MONITOR OUT The amplifier that drives AUX VIDEO OUT also drives PIX MONITOR OUT The only difference between the two outputs is that PIX MONITOR OUT contains the line strobe when the waveform monitor is in one of the LINE SELECTOR modes This output when connected to a picture monitor enables the user to view the waveform monitor display asa television picture and at the same time to see the exact location of the line or lines 15 LINE selected by the LINE SELECTOR controls Some picture monitors do not react favorably when the inserted line strobe crosses the field sync area External synchronization of the picture monitor should eliminate the unfavorable reaction REV A SEP 1980 Using LINE STROBE OUT The LINE STROBE OUT is an ac coupled positive going TTL compatible output time coincident with the line or lines selected by the LINE SELECTOR controls This signal can be used to brighten a picture monitor display or can be su
90. d alongside a 9 inch Conrac Picture Monitor in a standard 19 inch rack A cradle and bezel are also available for mounting two 1480C s side by side For mounting 9 inch SNA 9 Picture Monitor Requires 834 inches rack space Cradle Assembly 014 0020 00 Bezel for mounting 1480C on operator s left 014 0023 00 Bezel for mounting 1480C on operator s right 014 0024 00 For mounting two 1480C Waveform Moni tors side by side requires 834 inches rack space Cradle Assembly 014 0020 00 Bezel 5 65 MN nea Sy 014 0022 00 1480R Cradle Assembly For mounting the 1480R in a WECO backless rack Order 426 0309 00 Copyright 1977 Tektronix Inc All rights reserved Printed in U S A Foreign and U S A Products of Tektronix Inc are covered by Foreign and U S A Patents and or Patents Pending Information in this publication supersedes all previously published material Specification and price change privileges reserved TEKTRONIX TEK SCOPE MOBILE TELEQUIPMENT and i are registered trademarks of Tektronix Inc P O Box 500 Beaverton Oregon 97077 Phone Area Code 503 644 0161 TWX 910 467 5 77 8708 Cable TEKTRONIX More than 50 Subsidiaries Distributors around the world REV A SEP 1980 AX 3165 1 3 43 Section 4 1480 Series SN B060000 up SPECIFICATION This section covers the Electrical Mechanical and Environmental specification of 1480 Series Waveform Monitors In
91. d in suitable texts 2 Impedance Transformation The AUX VIDEO connector provides an output with a 759 source impedance and the same polarity as the output for any of the inputs to the waveform monitor In particular it may be used in conjunction with the X 10 probe as an impedance transformer between a very high and a 75 impedance This is invaluable when one wishes to drive another instrument with a 759 input impedance from a probe for instance a TEKTRONIX vector Scope Conclusions The examples given above are typical of the uses to which ihe AUX VIDEO facility can be put and clearly demonstrate ihe potential it possesses for increasing the field of utilisa lion of the 1480 Series of Waveform Monitors It is hoped they will suggest further ideas for employing this facility in the solution of operational and olher problems Application Notes 1480 Series SN B060000 up References 1 Bode Network Analysis and Feedback Amplifier Design D Van Nostrand 1945 2 Landee Davis and Albrecht Electronic Designer s Hand book McGraw Hill 1952 Appendix 1 Resistance Values for 75 Atlenuator Pads R2 2 Ra 9 Rs 2 Re 9 6 51k 13 0k 0 86 6 48k 3 26k 6 51k 171 3 22k 217k 434k 255 2 13k 1 63k 3 26k 3 38 1 59k 130k 261k 420 1 27k 1 08k 217k 5 01 105k 929 1 86k 5 81 894 813 1 63k 660 777 722 145k 7 38 687 650 130k 816 615 591 1 19k 892 556 541 1039 1 09k 9 68 506 499 1127 1 00k 1046 465 463 1214 932 1
92. d input to the vertical amplifier The response characteristics are the same as FLAT REV A SEP 1980 9 DC RESTORER Eliminates vertical drift and provides stable displays despite changes in signal amplitude and average luminance levels Buttons select the clamping speed and clamping location on the com posite video signal In the DIFF D STEP response mode the dc restoration is automatically turned off In the LOW PASS response mode SYNC TIP is automatically locked out In the BANDPASS response modes the dc restorer circuits still operate but becausethe filters do not pass dc or a low frequency component dc restoration neither adds to nor detracts from measurements made with these filters OFF Disables the dc restoration circuits The trace level will follow the dc content of the incoming signal A Left front section rackmount model Operating Instructions 1480 Series SN B060000 up SLOW Selects a time constant long enough to display mains hum and field ratetilt in the video signal FAST Selects instantaneous clamping to eliminate hum and tilt in the display Attenuates mains hum at least 26 dB BACK PORCH Sets the clamping sample pulse to Occur at back porch time in the composite video waveform SYNC TIP Sets the clamping sample pulse to occur at sync tip time in the composite video waveform bod 1485C WAVEFORM MONITOR VERTICAL POSITION B Left front section cabinet model
93. d television triggering Differential Comparator Bandwidth dc to 30 MHz minimum deflection factor 1 mV Div two channels capable of differential operation Dual Trace Amplifier Vertical amplifier independent of the Differential Comparator Bandwidth dc to 30 MHz minimum deflection factor 5 mV Div Example a TEKTRONIX 7603 with 7B53A Option 5 Dual Time Base 7A13 Differential Comparator and 7A18 Dual Trace Amplifier 8 Return Loss Bridge Tektronix Part Number 015 0149 00 9 Television Test Signal Generator Capable of generating 3 step and 4 step RGB YRGB signals Example a TEKTRONIX 067 0601 00 Television Test Signal Generator 10 75 Q Coaxial Cable 42 inches long four each Tektronix Part Number 012 0074 00 11 75 Q End Line Termination Four each Tektronix Part Number 011 0102 00 12 75 Q Feed Through Termination Two each matched within 0 2 Supplied as accessories with the Return Loss Bridge item 8 Tektronix Part Number 011 0103 00 13 75 Q Feed Through Termination Tektronix Part Number 011 0103 02 Two each 14 50 Q to 75 Q Minimum Loss Attenuator Tektronix Part Number 011 0057 00 15 Attenuators 2X Tektronix Part Number 011 0069 02 5X Tektronix Part Number 011 0060 02 10X Tektronix Part Number 011 0059 02 16 Bnc Cable Tee Connector Tektronix Part Number 067 0525 00 17 P6101 1X Probe Tektronix Part Number 010 61 01 01 18 P6105 10X Probe Tektronix Part Number 010 6105 0
94. d to readjust the gain to normal since there will now be a loss of 1 5 dB in the circuit This will present no problem if the monitor is used with a 752 termination since the loss can be made good simply by recalibrating the instru ment with the preset variable gain control on the front panel but with a loop through connection it will become necessary lo insert an amplifier In this case where video gain amplifiers are available to standard values such as 3 dB or 6 dB it will be most convenient to choose this value as the basic equaliser loss Table I Values of 2C and 2L as a Function of Subcarrier Boost 3 58 MHz i 4 48 MHz Boost dB 2C nF 2L uH 2C nF 2L uH OA 091 543 0 74 42 02 1 34 7 6 1 08 64 0 3 mA 9 6 1 38 78 04 2 06 116 1 67 94 0 5 242 13 6 196 11 0 06 2 79 15 7 2 26 127 07 3 20 18 0 259 146 08 3 67 20 6 2 96 167 09 4 20 23 6 3 39 19 1 10 4 85 27 3 3 92 22 4 Longer cable lengths can be equalised by exactly the same procedure with the exception that the very simple configura lion employed above will have to be replaced by a more com plex structure The one recommended does not in fact follow the desired law of attenuation particularly well but where the loss at subcarrier frequency is no more than say 1 dB the eriors are negligibly small and any greater complexity of the equaliser arm is not justified by any improvement in per formance Details of networks suitable for cable equalisation in general can be foun
95. dance loop thru inputs for composite sync Compensated for 75 Q not internally terminated 29 External Sync Selector Switch Selects source for external sync information EXT SYNC SWITCHED WITH INPUT SWITCH A OR B External sync input follows setting of the front panel INPUT switch EXT SYNC ALWAYS A External sync input is always from the A input regardless of the INPUT Switch setting 30 EXTERNAL HORIZ IN Requires a 5 volt positive going input signal starting at O volt for full screen deflection Dc coupled Input impedance is 10 kQ No crt blanking Normally shipped disabled to protect the cathode ray tube Internal wiring change is required to activate this mode See note on diagram 9 31 LINE STROBE OUT A line selector strobe pulse that is present only during Line Selector mode of opera tion 32 PIX MONITOR OUT A composite video output of incoming video signal picked off after the vertical preamp but before the Response filters Line Strobe is added to the output signal in Line Selector modes of operation Inter nally terminated in 75 Q 33 AUX VIDEO OUT Same as PIX MONITOR OUT except that the Line Strobe pulse is not available Internal ly terminated in 75 Q 34 AUX VIDEO IN Video input internally terminated in 75 Q 1 5 dB gain allows for loss of passive networks that may be used Enters the vertical system after the Response filters 35 J9034 RGB input connector providing
96. deo signal from the video signal source to the 1480 Series VIDEO INPUT A connec tor and terminate the loop thru connector in 75 Q b Setup the video signal source to supply known signals in the vertical interval For example the NTSC STOC1 composite test signal on line 17 of the even field c Set the 1480 Series RESPONSE switch to FLAT DISPLAY selector to 2 FIELD and MAGNIFIER switch to X20 5 9 Performance Verification 1480 Series SN B060000 up d Horizontally position the interval that occurs between the displayed fields to graticule center When the field selection pushbutton that corresponds to the even field is pressed the odd field interval will be displayed Assume that line 17 of the even field is carrying the composite test signal When the EVEN pushbutton is pressed the displayed interval is for the odd field and no composite test signal will be displayed on line 17 Procedure for checking PAL fields using the Bruch Blanking Sequence appears in Television Products Application Note number 16 Verifying the Bruch Blank ing Sequence which is located in Section 3 of this instruction manual Care should be exercised when making this check because the sequence may be in error on the video coming from the video signal source 29 Check Line Selection a Connect the video signal source composite video output to the VIDEO INPUT Aconnector and terminate the loop thru connector in 75 Q b Set the VOLTS FULL
97. e reference 700 mV at 4 43 MHz at 3 9 to 4 1 MHz and 4 7 to 4 9 MHz 5 7 Performance Verification 1480 Series SN B060000 up 19 Check Calibrator Accuracy a Press the CAL and DC RESTORER SYNC TIP pushbuttons b Connect the AUX VIDEO OUT through 75 Q ter mination to the test oscilloscope differential comparator input c Set the test oscilloscope Time Div to 50 s Volts Div to 50 mV andfor comparison voltage operation d Connect the test oscilloscope differential com parator Vc out to the digital voltmeter input Connect the other digital voltmeter lead to the test oscilloscope ground e Set the test oscilloscope differential comparator Vc to 0000 Vertically position the bottom of the square wave to graticule center Note the digital voltmeter reading f Rotate the differential comparator Fine Comparison Voltage control to set the top of the square wave to graticule center Check that the amplitude of the square wave is 1 V 2 mV g Press the DC RESTORER BACK PORCH pushbut ton h Check for a square wave amplitude of 700 mV 0 5 3 5 mV for models with CCIR internal graticule scale and 100 IRE 0 5 0 5 IRE in NTSC models 20 Check GAIN a Press the DC RESTORER SYNC TIP pushbutton b Check that the 1480 Series display is 1 volt 0 2 c Adjust the front panel GAIN control for a 1 volt display if necessary 21 Check VOLTS FULL SCALE accuracy a Connect the television test signal gene
98. e pattern size as the internal graticule The second pattern size is slightly smaller than the internal pattern and is designed to remove parallax effects when using an oscilloscope camera CONTROLS Some of the pushbuttons on the front panel are color coded dark gray With all these buttons pushed in the waveform monitor display will be normal according to the vertical response mode selected All pushbuttons have functional labels Within their own groups the buttons are self cancelling when pushed individually In certain operating modes the OPER and CAL button pair will be pushed in at the same time as well as pairs of the FIELD buttons Almost all of the functions controls connectors and indicators needed and used by any of the models in the series are present on the 1485 NTSC PAL dual standard instrument Therefore the 1485 is used as the example to illustrate and describe the features of the 1480 Series of Waveform Monitors Controls listed in the following are referenced to Fig 2 is 1 POWER Applies or removes mains voltage to the power transformer primary 2 POWER ON Lights to indicate presence of mains voltage at power transformer primary 3 SIGNAL Lights indicate 50 Hz or 60 Hz field rate input signal 1485 only 22 4 INPUT Selects A or B VIDEO INPUTS or A B differentially ac or dc coupling and the X10 PROBE INPUT if the waveform monitor is equipped with Option 1 5 VOLTS FULL SCALE
99. eak or 140 IRE amplitude display Oo NNNM 255501 Fig 1 3 Overlayed levels al sync tip 1 3 Unpacking and Incoming Inspection 1480 Series SN B060000 up 2 Vertical Attenuation Change VOLTS FULL SCALE to 0 5 and vertically position the display so that the sync pulse amplitude can be measured It should be double the amplitude seen with the VOLTS FULL SCALE at 1 0 Adjust the VAR VOLTS FULL SCALE for a sync pulse amplitude equal to that observed at 1 0 VOLTS FULL SCALE Change VOLTS FULL SCALE to 0 2 and check for sync pulse amplitude 2 5 times greater than the amplitude set with the variable control See Fig 1 4 Return VAR to its detented position and set the VOLTS FULL SCALE to 1 0 2338 03 Fig 1 4 Sync amplitude measurement a normal b 2 5X increased 1 4 3 DC RESTORER Depress the DC RESTORER OFF pushbutton and position the display so that the baseline is at the blanking level 300 mV or 0 IRE Push in the FAST DC RESTORER and note a rapid shift to a new average level Turn off the DC RESTORER OFF Push in the SLOW DC RESTORER and note rapid shift followed by a slow change to a new average level Depress the SYNC TIP pushbutton and check for a change in the average level 4 RESPONSE SWITCH This step is written using a composite test signal however RESPONSE positions can be checked with any of the normally available test signals Fig 1 5a isan NTSC Composite Test Signal
100. ecks Catalog Option 1 provides an ac coupled probe input to the vertical channel Operating instructions are covered later in this section Horizontal Calibrated magnification to X50 and ahigh writing rate crt allow viewing of fast rise low repetition rate signals such as the 100 ns risetime of a test signal on a single line out of the four fields in the PAL system In high magnification positions the crt is automatically brighten ed REV A SEP 1980 Timebase Foldback a waveform comparision feature provides for locating and overlaying a portion of a line rate display with another portion of the same display For instance in measuring pulse to bar ratio the pulse can be displayed directly beneath the center of the bar The horizontal display can be any of the following 1 Digitally selected line or two lines depending on sweep speed selected 2 Continuously variable selection of line or two lines 3 2 fields fields 1 and 3 or 2 and 4 for NTSC 4 One brightened linefrom 2fields ortwo brightened lines 5 15 lines either brightened from 2 fields or superimposed on one another at line rate Continuously variable selection of the 15 line group is provided 6 Option 7 only seconds sweep Slow Sweep 4 to 12 7 All fields permits simultaneous viewing of oneline or a group of lines from each field 8 External signal at external horizontal input is displayed This mode is normally
101. ed at this time that the most sensilive test signal for this purpose is a 52 S white bar however this is not normally an Insertion Test Signal Figure 6 shows the field time distortion tilt of a while bar signal Figure 6 Field time distortion observed with a white bar To make a similar though less sensitive in service observation one Insertion Test Signal must be deleted For an example let line 17 be deleted while lines 18 330 and 331 continue to carry the assigned test signals By displaying ALL FIELDS as shown in Figure 7 observe that lines 18 and 331 display different video levels This is field time distortion which may also be thought of as a residue of line 330 energy due to the tilt field time dis Figure 7 Field time distortion observed with ITS tortion Sensitivity of Ihe lest is dependent on the energy con tained in the test signal the energy available on line 330 is less than that of a white bar signal By comparing the results obtained in Figure 6 and 7 it is obvious that the in service measurement is less sensitive than using the optimum signal However this is still a powerful measurement technique in that it can be performed in service using established test signals With the inclusion of ALL FIELDS and the other new display features covered by the other Application Notes in this series the 1480 Series Waveform Monitor has widened the area of in service measurement Tests that were either impo
102. el with the 1480 Series of Waveform Monitors by LE Weaver Tektronix European TV Engineering Consultant The amplitude of the video signal needs to be set to its correct value within a very small tolerance range at all points in the TV signal chain where such waveforms are found This requirement has been fully taken into account in the de sign of the 1480 Series of Waveform Monitors which provide the user not only with the conventional square wave calibrating signal but also with level measuring facilities of a kind not pre viously found in commercial instruments The method employed is not in fact novel since it was first described more than 10 years ago and it has for a long time been in standard operational use by a TV broadcasting organ isation internationally known for its high standards but its merits as an operational procedure do not seem to have been more widely recognised until now How it Operates The basic principle is remarkably simple although it is very easy to make it appear quite complicated For the sake of clarity therefore suppose it is required to set the overall amplitude of the video signal by means of an ITS signal say the internation ally agreed line 17 By definition this amplitude is the voltage difference between the mid point of the top of the luminance bar and the mid point of sync bottom Now set up the waveform monitor as follows INPUT A looped through or correctly terminated at input
103. elevision Waveform Monitors prove a combination of high performance and versatility They can be single standard models or dual standard combinations available for most of the world s operating television systems 1480 Series are available in either cabinet or rackmount configurations designed for use in control rooms video tape installations or transmitter plants Many catalog options are available to closely tailor a 1480 Series Waveform Monitor to specific measurement applications FEATURES Vertical A distortion free vertical overscan capability offers increased high resolution measurements Coupled witha wide vertical positioning range any portion of a nominal 1 volt composite video signal can be viewed at any position of the VOLTS FULL SCALE settings The vertical response can be specialized by selecting one of several filters from the front panel ranging from LOW PASS through IRE and FLAT to BANDPASS around certain color subcarrier frequencies In addition the same switch can select a differentiated steps display or an auxiliary video input at the rear panel A versatile DC Restorer offers clamping on the back porch or at the sync tip of the composite video waveform Fast and slow clamping speeds can be selected to suit specific needs An internal calibration squarewave is available at the push of a button This calibration signal can also be used to offset the displayed video signal for quick amplitude accuracy ch
104. ents for VIRS comparison This comparison is not intended for diagnostic purposes but rather to help alert an operator to a potential problem or to allow him to adjust signal parameters The program video should not be subjected to this deletion of the program related VIRS or the reinsertion of a locally generated VIR Signal This comparison technique should only be done on a monitoring circuit and not on the program line itself Observing Field Time Distortion It has not been praclical until now to make in service field time distortion tilt measurements With the All Fields dis play mode of the 1480 Series Waveform Monitor it can be done with relative ease The accuracy of this measurement will be somewhat less than the current white bar test method used in full field but this is to be expected since much less energy will be con tained in a VIT Signal Figure 6 shows field time distortion measured with a white bar 3 42 Figure 6 Field Time Distortion observed with a 100 IRE Flat Field signal This observation technique requires deleting the VIT Signal from a selected line in one field while maintaining a VIT Signal of maximum energy content on the same line in the opposite field The result will be a displayed difference in level in subsequent lines due to field time distortion It may be considered as the residue of energy from the VIT Signal due to tilt The signal used for Figure 7a is from the noise pedestal generated
105. erlooked and all chromi nance amplitude measurements will be in error by that amount For instance a typical high quality flexible coaxial cable such as RG 59 U has a loss at 4 43 MHz of about 0 75 dB per 100 feet Now as a result of the constraints of bay wiring it is very easy to have 20 feet or more of such cable between the wave form monitor input connector and a switching matrix say in round numbers a chrominance luminance gain inequality of 0 2 dB at the least This is a significant error which should not be tolerated The answer is to insert a simple constant resist ance equaliser in series with the input video feed The design procedure is as follows The simplest equalisr configuration likely to give the required characteristic will al ways be chosen first In this instance it will consist of a resis ior and a capacitor in parallel for the series arm as in Figure 4 The next step is to select a value for the basic loss that is the loss at zero frequency which must obviously always be some what larger than the required subcarrier boost For the sake of example this will be taken to be 1 5 dB which is given in series insertion by a resistance of 28 32 In most cases it is found easier to switch capacitors than inductors so the series insertion form is preferred This resistor is then connected be tween AUX VIDEO OUT and AUX VIDEO IN and arrangements 3 32 made to switch capacitors across it as required The values for v
106. es a change in sweep speed of about 3 to 1 50 60 Hertz Triggering uses the rear panel AUX SYNC INPUT connectors Triggering mode is selected by simultaneously depressing both INT and EXT SYNC pushbuttons Operating Instructions 1480 Series SN B060000 up TR 70C TR 70C PUSHBUTTON 1480 Series DISPLAY PUSHBUTTON Displays VIDEO INPUT A signal as a Displays the video from the Color reference to allow for correct level Automatic Time Corrector adjustments 1813 64 OUT Displays the video output from the Displays the TR 70C output video to demodulator allow for level checking 1813 62 1813 65 FM LEVEL i the Aut ti Head by head display of detected FM Time ie ia from OMBE from the playback head amplifier 1813 66 Fig 2 10 Operating waveforms from RCA Video Tape Recorder model TR70C 2 15 Operating Instructions 1480 Series SN B060000 up i TR 70C TR 70C 5 PUSHBUTTON 1480 Series DISPLAY ATC Displays capstan servo control track Displays error signal from the signal in the playback mode Automatic Time Corrector module 1813 67 1813 70 CT PB Record Mode Displays control track during record for check of proper control track signal Displays error signal from the Color Automatic Time Corrector module
107. ese distortions is field rale phase modulation of chrominance This dislortion appears as a hue shift for the first few lines of picture usually after vertical blanking Figure 16 shows the demodulated output of a television transmitter with about 3 of chrominance phase modulation The 15 line display mode of the TEKTRONIX 1480 Series of Waveform Monitors is a valuable tool for many unique video measurements providing previously unavailable capabilities for measurement in videotape recorders transmitters and other areas of television operalions The ability to analyze the characteristics of each head of a videotape recorder provides an excellent means for optimizing record reproduce performance The individual head noise measurement tech nique can save costly production time by indicating the need for head replacement well in advance of noise banding in multiple generations Field rate related distortions are also readily apparent using the expanded measurement capa bilities of the TEKTRONIX 1480 Series of Television Wave form Monitors Figure 16 Field time chrominance phase modulation of a visual transmitter Copyright 1975 Teklronix inc All rights reserved Printed in U S A Foreign and U S A Products of Tektronix Inc are covered by Foreign and U S A Patents and or Palents Pending Information in this publication supersedes all previously Published material Specificalion and price change privileges reserved TEKTRON
108. evel to the 0 IRE Unit reference line and use the VARiable VOLTS FULL SCALE to adjust for a white flag amplitude of 100 IRE Units Set the 1480 VOLTS FULL SCALE to 0 5 burst amplitude equals 100 Check for equal amplitude of the multi burst packets above and below the pedestal even order harmonic distor lion To measure the frequency response successively position the negative peak of each multiburst packet lo the 0 IRE Unit reference line and measure the peak positive amplitude of the packet Color Bar Chrominance Amplitude The chrominance amplitude of 7595 amplitude color bars can be rapidly checked on the new graticule using the 3 38 R scale There are only three chromi nance amplitudes present in the six color bars 62 82 and 88 IRE Units See Figure 16 Figure 16 Measuring Color Bar Chromi nance Amplitude of the red and blue color bars Amplitude 88 and 62 IRE respec tively To measure each color bar amplitude place the negative peak of the bar on the 20 IRE Unit graticule line below the R scale The displayed peak amplitudes become 82 102 and 108 IRE Units respectively for the 62 82 and 88 IRE Unit amplitude color bars Using Burst for Waveform Monitor Timing Check Timing accuracy can be quickly verified by comparing the dura tion of burst cycles against the timing scale on the 30 IRE Unit graticule line See Figure 17 Figure 17 Time Base Accuracy check at 100 ns division sweep
109. external switching control and signal access for RGB YRGB displays 36 AUX SYNC IN This input is used in Options 4 5 and 7 An uncompensated loop thru input used for either tone wheel sync input Options 4 and 5 or the 50 60 Hz triggering signal Option 7 37 J9036 Blanking mounting location for possible remote control connector 38 Main Fuse and Holder 39 Motor Base connector Receptacle 3 bladed con nector to receive power cord Contains an RFI filter GRATICULES Patterns Two basic patterns appear as 1480 Series internal graticules They are the 625 line 50 Hz K Factor CCIR Composite combination shown in Fig 2 4 and a 525 line 60 Hz Composite graticule designated Graticule A Fig 2 5 Both of these patterns are available in external graticules in full scale and a 3 reduced photo version 07 s 65 K275 LL 03 uM Fig 2 4 CCIR Composite K Factor combination graticule supplied with 1480 Series 625 50 instruments ESI L0 2X 5X Fig 2 5 NTSC Composite Graticule A supplied with 1480 and 1485 REV C SEP 1980 Photo graticules are reduced in scale to eliminate parallax errors The CCIR Composite K Factor graticule the NTSC Composite Graticule A and a special Short Time Distortion measurement graticule for NTSC Graticule B are all available in both visual and photo scales The special Short Time Distortion graticule for NTSC Graticule B are all available in bot
110. f output and input impedances which are pure 75 resistances It therefore becomes possible to con struct a two terminal network from variable resistors capacitors and inductors which is capable of providing a very large range of loss characterislics when inserted in the AUX VIDEO path Any one of these can then be converted immediately inlo the corresponding constant resislance equaliser by a simple numeri cal process 3 31 Application Notes 1480 Series SN B060000 up It might be mentioned that this is a very practical and efficient procedure which has been used professionally in the U K for example for the routine equalisation of coaxial cable circuits and special equipment has been designed for the purpose Ro Ro Il Yo Z2 21 Zz Ro Z Ro Insertion loss 1 t 1 nserlion loss Re zZ Figure 3 Equivalence between Constant Resistance Equaliser and 2 Terminal Networks in Series and Shunt Inser tion Illustration of Design Procedure Great care is taken with the 1480 Series to make sure that the gain is exactly the same in both the luminance and chromi nance regions However when the monitor is installed the actual point at which the video signal is switched to its input is often physically separated from the input connector by an appreciable length of coaxial cable It follows that the wave form monitor will have in effect a chrominance luminance gain inequality which may be completely ov
111. f the options for the 1480 This equip ment is listed at the beginning of the optional step to be performed If this instrument contains options other than 2 3 or 6 be sure to check the Additional Equipment Required list for that option 1 Video Signal Source Capable of generating color bars composite sync and modulated staircase test signals Standard Recommended Instrument NTSC Tektronix 140 PAL Tektronix 145 PAL M Tektronix 145 M 2 Digital Voltmeter Accurate within 0 1 for dc volts from 4500 to 200 V Example TEKTRONIX DM 501 with a high voltage probe Tektronix Part Number 010 0277 00 See item 6 3 Leveled Sine Wave Generator Capable of amplitudes from 0 2 volt peak to peak to 5 volts peak to peak frequency range from 50 kHz reference to 10 MHz Example a TEKTRONIX SG 503 See item 6 4 Time Mark Generator Capable of generating time marks at intervals from 100 nsto 10 us with accuracy adjustable to within 1 part in 107 Example A TEKTRONIX 184 if available 5 Ramp Generator Capable of generating a 5 volt ramp Example a TEKTRONIX RG 501 See item 6 6 Power Module For powering and housing TEKTRONIX DM 501 TG 501 RG 501 and SG 503 units Required if using these units TEKTRONIX TM 504 5 1 Performance Verification 1480 Series SN B060000 up 7 Test Oscilloscope Dual Time Base Range from 50 ns Div to 5 s Div with provisions for a delaying sweep an
112. frequency Rejection of common to chassis in Floating Ground mode At least 50 dB at mains frequency VARiable VOLTS FULL SCALE Gain Range 0 5 1 to 1 4 1 Common Mode Rejection Ration INPUT A B with 1 V peak to peak common mode signal 60 Hz at least 46 dB 15 kHz at least 46 dB 4 43 MHz at least 34 dB Vertical Overscan 1 V peak to peak Composite Video Signal No added signal degradation to 5 MHz 0 5 and 0 2 Volts Full Scale 5 MHz to 10 MHz 3 degradation at two screen heights 0 5 Volts Full Scale 8 degradation at five screen heights 0 2 Volts Full Scale Maximum setting of VARiable VOLTS FULL SCALE Vertical Performance can be degraded up to 296 4 2 REV B MAY 1980 Specification 1480 Series SN B060000 up Table 4 1 cont Characteristic Performance Requirement Supplemental Information Frequency Response INPUT A amp B AUXiliary VIDEO Flat 50 kHz 5 MHz 2 INPUT through AUXiliary VIDEO 5 MHz 8 MHz 2 3 from 50 kHz reference OUTput or Picture PIX 8 MHz 10 MHz 2 5 from 50 kHz reference MONITOR OUTput Additive calibrator mode to 5 MHz only NOTE In the Performance Verification Section 5 and the Adjustment Procedure Section 8 of this manual make all checks and adjustments of vertical bandpass to the Specification noted above Rolloff must fall between the two curves 94
113. g gered so that the centre of the bar appears vertically above the peak of the pulse However as such scopes were not designed to do this it is just a bit tricky and inconvenient and in the case of in service measurements using insertion test signals VITS conventional double triggering cannot be used at all Tektronix recognizing the importance of this kind of mea surement capability has provided its new 1480 Series Wave form Monitor with time base foldback This new feature is easy to use and works on insertion test signals VITS which conventional double triggering cannot do It is not limited to in service testing it is very valuable in laboratory measurements where high precision is required Figure 2 REV A SEP 1980 1485C WAVEFORM MONITOR SIGN sou SIGNAL sonz VERTICAL POSITION TRACE GAIN ROTATION eo RESPONSE BLE Se oc A AC os creep e m 22 8 D A AB oncat t DC RESTORER BOTH IN CHA CAL CAL OUTPUT Figure 3 Under the front panel label WAVEFORM COMPARISON two concentric controls LOCATE and OVERLAY control the time base foldback circuit see Figure 3 A red warning lamp is ON whenever the foldback is switched ON A switch on the OVERLAY outer concentric contro clockwise end enables the foldback circuit and turns on the lamp as the control is rotated counter clockwise To indicate precisely where the foldback will occur in time an intensity m
114. g pro cedure Rotate the HORIZONTAL POSITION knob until the mid point of the bar top coincides with the right hand vertical scale line Ad just the VERTICAL POSITION control until the signal black level is in coincidence with point B5 Figure 6 The amplitude of the picture component can then be read against the graduated scale At the same time the amplitude of the sync pulse can be read from the lower graduated scale Figure 6 Check of video level References 1 BBC and IBA Specification of Television Standards for 625 Line System Transmissions 2 CMTT Document CMTT 187 E Measurement of insertion gain by means of insertion of test line signals November 1973 3 CMTT Document CMTT 189 E Measurement of baseline dis tortion after trailing edges of slep function signals Novem ber 1973 Appendix Additional Measurements Part 7 Check of Time Calibration PAL Signal Controls MAG x 50 DISPLAY 10 us div or 5 us div LINE SELECTOR DIG any convenient line FIELD 1and3 or2 and 4 SYNC INT AFC or DIRECT The time calibration of the waveform monitor with a PAL signal may be quickly and conveniently checked against a video signal by the following procedure Set the controls as indicated and rotate the HORIZONTAL POSITION control until the burst near the start of the trace is displayed as in Figure 7 In spite of the low repetition rate the crossover points of the superimposed sine waves will be quite clearly defined It s
115. g when the correct level has been achieved which is free from parallax error and at the same time independent of changes in average picture level because of the operation of the D C restorer REV A SEP 1980 Setting the Overall Level The basic practical procedure is therefore as follows Check that the correct waveform is being displayed this should appear at two levels as has been explained above Select a convenient horizontal graticule line as a reference and position the display so that the sync bottom of the upper waveform and the bar top of the lower waveform are roughly equidistant about this line Then as the level is varied it will be found very simple to bring the sync bottom and the bar top into the same horizontal line using the reference line as a guide This is the correct setting for the video level Sync bottom and bar top Located on same horizontal fine Figure 3a Correct setting with gain normal Figure 3b Level 10 high Figure 3c Level 10 low REV A SEP 1980 Application Notes 1480 Series SN B060000 up Improving the Resolution When the signal amplitude is increased from say 1 0 to 1 1 V the separation between the bar top and the bottom of sync also increases by the same amount which appears as one full grati cule division on the display Hence a voltage ratio of 1 1 1 i e 0 8dB is equivalent to a division If it can be assumed that the signal is not unduly noisy which will cer
116. gnals can be relied upon in picture generation areas it is possible to find long term distortions on distribution networks for example which can seriously affect the accuracy In these instances a modification of the transfer method is to be preferred A suitable technique is described in Part 6 of the Tektronix Application Note 12 Operational 625 Line Measurements with the 1480 Series of Waveform Monitors 1 Weaver L E The accurate measurement of video levels EBU Review Part A vol 69 pp 2 4 1961 Copyright 1974 Tektronix Inc All rights reserved Printed in U S A Forelgn and U S A Products of Tektronix Inc are covered by Foreign and U S A Patenls and or Palents Pending Information in this publication supersedes all previously published material Specification and price change privileges reserved TEKTRONIX SCOPE MOBILE TELEQUIPMENT and BX are registered trademarks of Tektronix Inc P O Box 500 Beaverton Oregon 97005 Phone Area Code 503 644 0161 9 74 Telex 36 0485 Cable TEKTRONIX Overseas Distribulors in over 40 Countries X 3069 REV A SEP 1980 Application Notes 1480 Series SN B060000 up application notes TEKTRONII rd committed to technical excellence V wuyuWwWu iu uuu Operational 625 Line Measurements with the 1480 Series of Waveform Monitors by L E Weaver Tektronix European TV Engineering Consultant The well planned and in certain respects novel dis
117. h visual and photo scales The special Short Time Distortion graticule for NTSC Graticule B is supplied with 1480 and 1485 only Graticule B is shown in Fig 2 6 Graticule B s two masks 2 and 5 are in accordance with IEEE Trial Standard 511 1974 Information on the use of all three major measurement graticules can be found in Tektronix Television Products Application Notes 12 and 20 contained in Section 3 of this manual Fig 2 6 NTSC Short Time Distortion measuring graticule Graticule B An NTSC non composite pattern is available as an optional extra cost external graticule Refer to the TV Products Catalog or call your local Tektronix represen tative Graticule horizontal scales are divided into 12 7 divisions along the horizontal line at blanking level The vertical graduations are scaled according to measuring units and ranges peculiar to each system mvV for the CCIR graticule and IRE units and percent modulation for NTSC The graticules are also marked for K factor tolerances and linear distortion measurements REV A SEP 1980 Operating Instructions 1480 Series SN B060000 up Internal With the SCALE ILLUM control pushed in the internal graticule is edge lighted The range of illumination is sufficient for comfortable viewing in a studio environment or for taking waveform pictures with Tektronix Oscilloscope Camera Systems The internal graticule offers parallax free viewing that greatly enhances
118. hat in Figure 4 and use Table 1 to determine if burst is occurring on the correct lines Follow the remainder of Table 1 using Figure 5 as a reference to check out the en tire Bruch blanking sequence o Figure 4 3 27 Application Notes 1480 Series SN B060000 up Figure 5a Figure 5b Figure Sc The switching used to check the Bruch blanking sequence can also be used to check burst phasing A minor operational change to a TEKTRONIX 520 Series Vectorscope 521 521A for 625 50 PAL or 522 522A for 525 60 PAL M provides an accurately phased display of the burst on selected line for a particular field Shift the lead that is on pin BO of the Sweep Circuit Board to pin BQ and lift the lead from pin BR Connect the 1480 Series Waveform Monitor LINE STROBE OUT to the Vectorscope Z AXIS INPUT and loop thru connect the video signal to one of the Vectorscope signal inputs Set the Vectorscope display to FULL FIELD Set the 1480 Series Waveform Monitor s LINE SELECTOR to 17 330 and depress the DIG pushbutton The Vectorscope is now displaying the phase of the burst for the selected lines as switched by the 1480 Series Waveform Moni ior s FIELD selection pushbuttons Burst phase is as follows Field 1 135 Field 2 225 Field 3 225 and Field 4 135 This Application Note has taken advantage of two of the 1480 Series Waveform Monitor s display features accurate field se lection and the 15 line display
119. hould then be pos sible to match these against the graduations provided for the purpose on the 0 1 graticule line If any appreciable error is noticed reference should be made to the instrument manual 3 9 Application Notes 1480 Series SN B060000 up With an NTSC signal due io the absence of the 25 Hz offset found with PAL there is of course no need to use a 2 field display rate Figure 7 Check of time calibration PAL Part 8 Measurement of Time of Fall of Bar Controls MAG x 50 DISPLAY 5 us div LINE SELECTOR DIG or 15 LINES according to test signal FIELD to suit test signal note with a full field test signal the 15 LINES facility provides a useful increase in brightness In some countries it has been the practice to check the per formance of equipment and links up to and beyond the nominal upper video frequency by the use of a 1T bar This is preferred since the faster decrease in amplitude of its higher harmonics Produces less severe ringing than is the case with the 1T pulse and the resultant waveforms are considered to be easier to interpret In particular the time of rise or fall of the 1T bar provides some indication of the equivalent rectangular bandwidth of the equip ment under test although the derivation of an exact figure from the output waveform is not straightforward unless the passband is Gaussian in shape The measurement of the time of fall of a bar waveform in the form of a video waveform
120. ibrated in terms of the actual figures read from the scale so that zero lobe amplitude would be taken as 1 0 CHROMINANCE LUMINANCE INEQUALITIES js icu d i dB dB COM oeLav Positive NEGATIVE NCUATIVE 1 siart Ne m A wet wer NJ REV A SEP 1980 As in the other measuremenis in this series improved resolu tion is furnished by the use of the increased gain positions of the VOLTS FULL SCALE control It is also helpful if the means appen to be available for this purpose to unlock the subcar rier frequency which results in a considerably beiter defined chrominance envelope Although the graticule has been designed primarily for use with the 20T pulse it may also be employed with a 10T pulse provided the readings of delay error are halved The gain error readings are identical Part 5 Luminance Non Linearity Control Settings MAG OFF Others As in Part 1 Check that the test signal amplitude is correct and adjust if necessary as given in Part 1 Rotate the HORIZONTAL POSITION control until the staircase waveform appears in the centre of the display Set the RE SPONSE control to the DIFF D STEP position when a group of 5 sine squared pulses will appear as a result of the differentia tion of the staircase transitions Adjust black level to coincide with the 0 3 line and shift the trace horizontally so that each pulse in turn is placed against the right hand linear scale
121. icule center and switch to DIFF D STEPS Adjust the VARiable VOLTS FULL SCALE for a 100 IRE Unit amplitude of the largest step spike See Figure 10 Figure 10 Luminance Non linearity meas ured with the Differentiated Step Display Luminance Non linearity 6 Horizontally position ihe smallest step spike to the R scale 2 IRE Units div and read the percentage of non linearity directly The formula for determining luminance non linearity in 96 according to the CCIR is 1 c x 100 M is the amplitude of the largest step and m is the smallest step This formula is con veniently simplified by holding M at 100 and subtracting m or 100 m It is also possible to fold back the 1480 s sweep to display m and M overlayed See Television Application Note 13 Time Base Fold Back A Novel Improve ment Over Double Triggering for Video Testing by Charles W Rhodes REV A SEP 1980 with ITS Part of Distribution System 148 ITS GENERATOR Deleting Field 2 ITS inserting new Field 2 ITS Application Notes 1480 Series SN B060000 up KP l l 1 Lan a a a a a ad Remainder of Distribution 1 System 1480 Series WAVEFORM MONITOR Figure 3 Simplified diagram of a distribution system showing reinsertion of field 2 ITS Now that the test signal assignments have been made all that remains is the comparison Since the even field line 19 test signal has traversed
122. ime distortion scales To increase resolution change the VOLTS FULL SCALE without changing VARiable VOLTS FULL SCALE to 0 5 for 2Y2 5 and 1 limits lo the L D meas urement box or to 0 2 for 1 and 0 4 limits See Figure 2 Figure 2 Line Time Distortion with in creased gain L D 0 4 Short Time Distortion At the lime of this writing the weighting characlerislics to be used to develop an outline for the 2T pulse and the T step REV A SEP 1980 Application Notes 1480 Series SN B060000 up transition are under discussion by indus iry committees For this reason Graticule A does not contain the traditional out line for the 2T pulse Instead an external graticule Graticule B containing a scaling of the outline given in CCIR Recommendation 421 1 is provided for 1480 s equipped with Graticule A If a different weighting factor is adopted for 525 60 standards new graticules and difierent nomenclature will be required Current plans call for changing the 2T pulse distortion nomenclature to P and T step distortion nomenclature to S to reflect these different weighting faclors Many broadcast organizations presently use and are familiar wilh 2T pulse to bar amplitude ratio measurements and for this reason the K scale is included on this new graticule The Kus scale is non linear It conforms with CCIR Rec ommendation 421 1 D a GRAT A 100 pomme measurement K 1
123. ing a TEKTRONIX 1430 Noise Measuring Set Figure 7 Head 1 noise measurement 50 dB noise Figure 8 Head 2 noise measurement 44 dB noise Figure 9 Head 3 noise measurement 45 dB noise Figure 10 Head 4 noise measurement 51 dB noise REV A SEP 1980 VTR Differential Phase and Gain Measurements Measuring differential gain and differential phase on a quad ruplex VTR has always been rather difficult because the vectorscope display of the distortion appears to be very noisy Figure 11 shows a typical full field display of a videotape machine playback signal Actually the display appears noisy because each individual head has slightly different differential gain and phase characteristics which are overlaid one on another in the full field measurement mode Each head and its associated amplifier and equalizer contribute their indi vidual characteristics to the full field display By properly adjusting the equalization on a head by head basis so that the individual head characteristics are essentially the same optimum performance may be realized and the objectionable effect of head to head differences in response will be elimi nated or reduced Differential gain and phase measurements of a videotape recorder on a head by head basis can be made using a 1480 Series Waveform Monitor and a TEK TRONIX 520 Series Vectorscope SET VECTOR TO CIRCLE Figure 11 Full field differential phase of quadruplex VT
124. ing probe BNC connector accepts most TEKTRONIX probes P6065A probe recommended 10X Probe Calibrator Output Voltage 1000 V 0 005 V or 0995 to 1005 V OPTION 4 TAPE T W SYNC Input NTSC Syncs to either a standard negative going composite sync pulse of 35 V to 45 V in amplitude or a 240 Hz negalive going tape recorder pulse 1 5 V to 45 V in amplitude 2 083 ms in width and 4 166 ms in period PAL Syncs to negalive going 200 Hz tape recorder pulse 15 to 45 V in amplitude 2 5 ms in width and 5 ms in period Mains Voltage Ranges 100 VAC 110 VAC 120 VAC 200 VAC 220 VAC 240 VAC 10 Fre quency 48 Hz lo 62 Hz Max Power Consump tion 75 W OPERATING TEMPERATURE O C to 50 C Dimensions and Weights 1480 C Series Height 825 in 21cm Width 850in 216cm Depth 1695in 430cm Net Weight 2151b 981kg Domestic shipping weight z2851b 12 9 kg Export packed weight S415 Ib 188 kg Two 1480 C Series Waveform Monitors can be mounted side by side or one mounted alongside an associated picture monitor in a standard 19 inch rack or console 1480 R Series Height 25in 133 cm Width T 19 0in 482cm Rack Depth 180in 457 cm INet Weight i 24 6 Ib 112 kg 2531 1b 24 1 kol 2751 1b 234 1 kgl Domestic shipping weight Export packed weight Instrument fits standard 19 inch rack ORDERING INFORMATION 1480C NTSC Wavelorm Monitor 1480R NTSC Waveform Monitor 148
125. intensified In 10 us DIVision the first line displayed is the digitally selected one Field Selection The FIELD Selector is a set of four push buttons providing positive field selection In the PAL systems where four distinct fields exist Bruch Sequence it is possible to select each field individually as well as the odd and even field pairs In NTSC the odd and even fields are all that are identifiable Specification 1480 Series SN B060000 up The display starts at about line 20 of the selected field and goes on through the next full field terminating at about line 8 ofthe next complimentary field Forexample starts on an even field and ends at the beginning of the next even field ALL FIELDS provides a method of time overlaying the even and odd fields All line selection modes are func tional however for 15 LINES and VARiable the VARiable LINE SELECTOR must be in the first field of a normal 2 FIELD display ALL FIELDS display is selected by simultaneously pushing the center two FIELD Selector pushbuttons Table 4 7 POWER SOURCE Characteristic Performance Requirement Supplemental Information Mains Voltage Ranges 100 Vac 10 110 Vac 10 120 Vac 10 200 Vac 10 220 Vac 10 240 Vac 10 Frequency 48 to 62 Hertz Crest Factor At least 1 3 75 watts Maximum Power Consumption Table 4 8 ENVIRONMENTAL CHARACTERISTICS
126. interest as previously described set up the vectorscope for the desired measurement place the VTR female guide in its proper position and make the measure ment on the vectorscope Only the lines selected by the Waveform Monitor will appear on the vectorscope screen so each head and its associated amplifier can be checked individually for differential gain and phase Figures 13 through 16 show the differential phase and gain character istics of a quadruplex VTR Notice how much more easily the necessary adjustments can be made by reference to these displays compared to attempting to do the same thing with a display like Figure 11 Differential gain and phase on a VTR are primarily functions of equalization so it is possible to optimize the playback equalization of each head for minimum distortion by adjusting the equalization while observing the vectorscope By looking at only one head at a time the operator can easily and quickly minimize these distortions 3 23 Application Notes 1480 Series SN B060000 up Figure 13 Differential Gain Figure 14 Differential Phase SET VECTOR TO CIRCLE Head 1 5 SET VECTOR SET VECTOR TO CIRCLE TO CIRCLE 190 Head 2 4 z R 40 100 Head 2 SET VECTOR TO CIRCLE 100 Head 3 6 SET VECTOR SET VECTOR TO CIRCLE TO CHG ja Head 4 896 Head 4 7 3 24 REV A SEP 1980 Checking Time Base Stability The 1480 includes automatic frequency control of the time base s
127. ion in the 5 us DIV DISPLAY and fifteen lines duration with the 15 LINES pushbutton pressed 31 Check Sync Range a Connect the video signal source composite video signal through a 5X attenuator and 75 Q termination to the VIDEO INPUT A connector b Set the VOLTS FULL SCALE selector to 0 2 RESPONSE selector to FLAT and MAGNIFIER switch to OFF c Check for a stable display d Remove the 5X attenuator and the 75 Q termination Connect the composite video directly to the VIDEO INPUT A connector e Check for a stable display f Connect the video signal source composite video output through four 75 Q terminations to the VIDEO INPUT A connector Connect the other side of the VIDEO INPUT A loop thru connector to the EXTERNAL SYNC A input connector g Press the SYNC EXT pushbutton and check for a stable display h Remove the four 75 Q terminations Connect the composite video signal directly to the VIDEO INPUT A connector and check for a stable display i Replace the composite video with composite sync connected through a 2X and a 10X attenuator and 75 2 termination j Check for a stable display k Remove the two attenuators and the 75 Q termina tion Connect the composite sync directly to the VIDEO INPUT A connector Check for a stable display 32 Check Sync Input Selector a Connect the video signal source composite video to the VIDEO INPUT A connector and terminate the loop thru connector in 75 Q
128. ity a Disconnect the cable from the time mark generator and connect it to the test signal generator Composite Video output Set the test signal generator for an APL Bounce signal b Check the start of the display Display begins at maximum APL c Change SLOW SWEEP TRIG PLRT to minus Check start of the sweep display should begin with trace at the blanking level Performance Verification 1480 Series SN B060000 up Option 7 50 60 Hertz Triggering Additional Equipment Required 1 Pulse generator capable of 5 V output into 50 Q from 5 Hz to 50 MHz with variable period and duration For example TEKTRONIX PG 501 A function generator such as the TEKTRONIX FG 503 may be substituted See item 6 of the Test Equipment Required list 2 Three Coaxial Cables 50 Q 42 bnc connectors 012 0057 01 3 One 50 9 Feed Through Termination bnc connectors 011 0049 01 4 One 50 Q X10 Attenuator bnc connectors 011 0059 02 44 Check 50 60 Hz Triggering Sensitivity a Connect the output of the pulse generator through a 50 Q coaxial cable to the 1480 Series AUX SYNC INPUT Loop thru connect with a 50 Q coaxial cable to the VIDEO INPUT A connector Connect another 50 Q coaxial cable from the other side of the VIDEO INPUT A loop thru connector to the test oscilloscope vertical input through the 50 Q feed through termination b Using the test oscilloscope as an amplitude monitor setthe pulse generator for3 volts of
129. l Fields display of test signals that are inserted in the vertical blanking interval a NTSC line 17 both fields b PAL lines 17 and 330 overlayed one 87 5 1 Fig 1 8 15 Line display with both active and vertical interval lines Unpacking and Incoming Inspection 1480 Series SN B060000 up 7 DISPLAY SELECTION a 2 FIELD Change the DISPLAY to 2 FIELD Depress the LINE SELECTOR OFF pushbutton Check for a full 2 field display including part ofthe first vertical interval See Fig 1 10 b 10 us DIV Change the DISPLAY to 10 us DIV and check for a 2 line display See Fig 1 11 c 5 us DIV Change the DISPLAY to 5 us DIV and check for a 1 line display See Fig 1 12 NOTE The EXTernal position of the 1480 Series DISPLAY switch is inactive unless an internal circuit change is made therefore it is not looked at while these familiarization steps are performed Fig 1 10 2 field display 1 8 Fig 1 12 A one line display of a test signal at 5 us Division 8 MAGNIFIER a Fixed MAGNIFIER Set the DISPLAY to 2 FIELD and the MAGNIFIER to 1 usethe HORIZONTAL POSITION to place the vertical interval at graticule center See Fig 1 13a Rotate the MAGNIFIER through its settings and check for a display similar to each of those in Fig 1 13a through 1 13f REV A SEP 1980 Unpacking and Incoming Inspection 1480 Series SN B060000 up
130. l Gain lt 025 al any APL Input Resistance 1 MY 2 nol including probe Input RC Product 20 js 05 not including probe BNC connector accepts most TEKTRONIX probes P6065A probe recommended 10X Probe Calibrator Output Voltage 1000 V 0 005 V or 0995 to 1 005 V OPTION 4 TAPE T W SYNC Input NTSC Syncs lo either a standard negative going composile sync pulse of 35 V to 45 V in amplilude or a 240 Hz negalive going tape recorder pulse 1 5 V lo 4 5 V in amplitude 2 083 ms in width and 4 166 ms in period PAL Syncs to negalive going 200 Hz tape recorder pulse 15 to 45 V in amplitude 2 5 ms in width and 5 ms in period Mains Voltage Ranges 100 VAC 110 VAC 120 VAC 200 VAC 220 VAC 240 VAC 10 Fre quency 48 Hz lo 62 Hz Max Power Consump tion 75 W OPERATING TEMPERATURE O C to 50 C Dimensions and Weights 1480 C Series Height 825im 21cm width 850in 216cm Depth 76 95 in 43 0 cm Net Weight et 2151lb 981kg Domestic shipping weight 2851b 12 9 kgl m4151b 18 8 kg lExport packed weight Two 1480 C Series Waveform Monitors can be mounted side by side or one mounted alongside an associated picture monitor in a standard 19 inch rack or console 1480 R Series Heit 525m 83cm Width De 190in 482 cml Rack Depth PS 18 0in 45 7 cml Net Weight 2460 11 2 kg Domestic shipping weight 53 1 1b 241 kg lExport packed weight 75 11b z341kg
131. liary video input response according to Table 5 1B 0 2 VOLTS FULL SCALE REV B SEP 1980 11 Check Common Mode Rejection a Connect the video signal source composite video output through a 75 N feed through termination and the bnc cable tee connector to the A and B VIDEO INPUTS Do not terminate the loop through connectors b Set the video signal source for a 90 APL average picture level modulated pedestal signal c Set the DISPLAY to 5 us Div INPUT to A B DC CPL D and VOLTS FULL SCALE to 0 2 d Check display amplitude for 70 mV or less 5 5 Performance Verification 1480 Series SN B060000 up 12 Check A and B Frequency Response a Connect the leveled sine wave generator output through the 50 Q to 75 Q minimum loss attenuator a75 Q feed thru termination and the bnc cable tee connector to the A and B VIDEO INPUTS Do not terminate the loop thru connectors b Set the leveled sine wave generator frequency to 50 kHz and amplitude for 140 IRE units or 1 volt display height c Set the leveled sine wave generator frequency to 5 MHz d Check for a display height of 140 IRE or 1 V 2 e Set INPUT to B AC CPL D f Check for a display height of 140 IRE or 1 V 3 296 g Check frequency response for A and B VIDEO INPUTS as in Table 5 2 Table 5 2 Frequency Limit 0 05 MHz Reference 140 IRE NTSC 1 V equivalent display height PAL 0 44 MHz 1 Volt 20 mV 0j 1401RE 28IRE 13
132. librator Tele vision Application Note 11 The Meas urement of Signal Level With the 1480 Series of Waveform Monitors by L E Weaver discusses an exlremely accurate method of setting vertical gain Insertion Gain In all measurements using television test signals whether full field or VITS signal level or insertion gain must be checked first The vertical sensitivity of the 1480 should first be checked 1 0 V equals 140 IRE Use the 5 zs DIV time base to display Copyright C 1975 Tektronix Inc All rights reserved REV A SEP 1980 Risetime and Falltime Graticule A has built in rise and fall time measurement capability Point R at 80 IRE Units aligns with T on the 0 IRE Unit reference line See Figure 11 Figure 11 Double exposure showing the measurement of rise and fall times of a T step T and T 120nsec To measure rise or fall time set the transition amplitude to 100 IRE Units use the VARiable VOLTS FULL SCALE Vertically position the display so that the transition is from the 10 IRE Unit line to the 90 IRE Unit line Use the 100 nsec div time base and horizontally position the rise or fall of the transition through point R on the short 2 IRE Unit div scale Measure the distance from point T on the 0 IRE Unit reference line to where the transition crosses the ref erence line Time div is 100 nsec the T step transitions shown in Figure 11 have a rise and fall time of 125 nsec In a
133. linear system risetime and falltime of the bar signal are equal Non lineari lies may affect risetime and falltime unequally Measuring both by the above method detects such non linear effects Bar Trail or Smear Bar trail occurs after a transition from white to black It is discussed in some detail in CMTT Document 189E how ever it need only be discussed here as the picture impairment appearing as streaking following white to black tran sitions To measure bar trail use the 100 nsec div time base Position the trailing edge of a 100 IRE Units step transition 0 100 IRE Units on graticule through the descending arrow at the 50 IRE Unit line intersection and measure displace ment on the and 10 IRE scale just to the right of point B This scale is properly located for 525 60 standards Figure 12 shows the bar trail measure ment using the white to blanking level transition of the staircase A transition of 250 nsec falltime must be used because faster falltime 1T may display ringing REV A SEP 1980 Application Notes 1480 Series SN B060000 up which would confuse the measurement DISPLAY with equa accuracy Figure 12 The Bar Trail measurement Bar Trail 5 6 The remote transmitter contro composite VIT Signal FCC 873 669 has 250 nsec step transitions for the white bar and the falling transition of the bar may be used Measuring Half Amplitude Duration of a Pulse Adjust the VARiable VOLTS F
134. mance Verification 1480 Series SN B060000 up 35 Check 10X PROBE GAIN a Press the OPER pushbutton Connect the video signal source composite video to the VIDEO INPUT A connector Terminate the loop thru connector with a 75 Q feed through termination Connect the 10X probe to the open end of the feed through termination b Compare displays with the INPUT switch alternate ly in PROBE and A positions Check for less than 3 3 mV change in amplitude from A to PROBE 36 Check 10X Probe HF Compensation a Check that the chrominance packets are identical in the A and PROBE positions of the INPUT switch 37 Check Probe Calibrator Amplitude a Connect the 10X probe between the test os cilloscope and the X10 PROBE CAL OUTPUT b Measure the CAL OUTPUT amplitude using the differential comparator comparison voltage Check for 1 V 0 5 0 5 mV Options 4 and 5 VTR Tone Wheel Sync Input Additional Equipment Required 1 Pulse Generator capable of 5 V output into 50 Q from 5 Hz to 50 MHz with variable period and duration For example Tektronix PG 501 See item 6 of Equipment Required List 2 One 067 0621 00 Calibration Fixture remote control for VTR waveform monitor 3 Two coaxial cables 50 Q 42 bnc connectors 012 0057 01 4 One 50 Q Feed through Termination 011 0049 01 38 Check Clamping a Connectthe pulse generator minus outputto the 1480 Series SYNC loop thru input connector using 50 O ca
135. measurement of distortions amplitudes and level setting adjustments External External graticules can be installed quickly and easily Simply unscrew the crt bezel cap nuts remove the crt bezel and fit the graticule over the faceplate with the printed side in Depending on the TV system for which the graticule is designed the Back Porch Cal Ampl switch see Fig 2 7 must be positionedtotheleft NTSC orright PAL position to match the locating hole at the lower edge of the external graticule Thus when the PULL FOR EXT SCALE ILLUM control is activated to turn on the external graticule lights the calibrator signal amplitude will be automatically selected when the DC RESTORER is in BACK PORCH SYNC TIP position always produces a 1 volt signal CAUTION P Ve AAA S Failure to place the switch in the proper position will cause its destruction and an erratic or nonexistent calibration signal S9955 Back Porch Cal Ampl 3 position slide switch PAL 700 mV Crt bezel removed 1813 12 Fig 2 7 Location of the Back Porch Cal Ampl switch 9955 Same location for both rackmount and cabinet model Operating Instructions 1480 Series SN B060000 up OPERATING PRECAUTIONS When operating the 1480 Series Waveform Monitors front panel controls can be set in a manner that exhibits anomalous displays The following discussion identifies those operating modes that should be avoided 1 In the ALL FIEL
136. ms Hum 30 ns Variable APL amp 4 V rms Hum 36 dB White Noise Jitter Reduction with Respec to While Noise gt 8 dB DIRECT Horiz Frequency Range lt 20 kHz Maximum Jitter with Respect to Inpul Sync 12 ns inpul Composite Video or Composite Sync from a 140 series Generator 20 ns Variable APL 20 ns Variable APL amp 4 V rms Hum 90 ns Variable APL amp 4 V Tum 36 dB While Noise EXTERNAL HORIZ IN Sensitivity 05 V div Linearity 1 RGB YRGB J9036 RGB Sweep Length Inter nally selected for normal sweep YRGB Sweep Length internally selected for 44 normal sweep WAVEFORM COMPARISON LOCATE Range suf ficient lo place LOCATE indicalion any place on 5 us DIV or unmagnified 10 4s DIV sweeps OVERLAY Range sufficient to overlay any se lected portion of 5 js DIV or unmagnified 10 us DIV on any other portion LINE STROBE OUT Strobe output of line or lines selected by VARIABLE 15 LINE or DIGI TAL line se eclor modes and the DISPLAY switch TTL amplitude ac coupled Time Con stant 1 aF 10 ke OPTION 1 10X Probe Channel Scale Factor adjustable to 1 V peak to peak equivalent display height GAIN Range 10 Gain to AUX VIDEO Unity 3 with gain adjusted for 1 V peak to peak equivalent display height Till lt 5 on 50 Hz square wave High Frequency Response 1 25 Hz to 5 MHz 3 5 MHz to 10 MHz Referenced to 50 kHz Differential Phase 0 25 at any APL Differen tia
137. n the crt X10 PROBE GAIN Adjusts the gain of the probe amplifier X10 PROBE CAL OUTPUT When the CAL pushbutton is depressed a 1 V calibrator signal for compensating the X10 probe is available Controls listed in the following are referenced to Fig 2 24 16 DISPLAY Selects the calibrated sweep rates and horizontal input mode in standard instruments In in struments that contain Option 7 the DISPLAY switch has two extra positions Slow Sweep Polarity and Slow Sweep Polarity 2 FIELD Displays two fields at 25 Hz or 30 Hz frame rates Sweep starts at line 16 of the vertical interval of the field or field pair selected by FIELD switch 10 us DIV Selects sweep rate to effectively display two line periods of either 525 line or 625 line systems The graticule horizontal scale is marked for 12 7 divor 127 us In 525 line systems a two line period equals 127 us in 625 line systems a two line period equals 128 us 5us DIV Selects sweep rate to effectively display one line period of either system EXT Selects the external horizontal input for dis play Normally shipped disabled to protect the cathode ray tube Internal wiring change is required to activate SEE NOTE ON DIAGRAM D OPTION 7 SLOW SWEEP TRIG PLRT Selects Slow Sweep and the triggering polarity for sweep origin SLOW SWEEP VAR Controls slow sweep rate over a range of approximately 4 to 12 seconds sweep Whenever slow sweep is selected
138. nally selected for 3 normal sweep YRGB Sweep Length internally selected for Y4 normal sweep WAVEFORM COMPARISON LOCATE Range sul ficient to place LOCATE indication any place on 5 us DIV or unmagnified 10 us DIV sweeps OVERLAY Range sufficient to overlay any se lected portion of 5 us DIV or unmagnified 10 us DIV on any other portion LINE STROBE OUT Strobe output of line or lines selected by VARIABLE 15 LINE or DIGI TAL line setector modes and the DISPLAY switch TTL amplitude ac coupled Time Con stant 1 uF 10 ke OPTION 1 10X Probe Channel Scale Factor adjustable to 1 V peak to peak equivalent display height GAIN Range 10 Gain to AUX VIDEO Unity 3 with gain adjusted for 1 V peak to peak equivalent display height Tilt 5 on 50 Hz square wave High Frequency Response 195 25 Hz to 5 MHz 3 5 MHz to 10 MHz Referenced to 50 kHz Differential Phase lt lt 0 25 at any APL Dilferen lial Gain lt 0 25 at any APL Input Resistance 1 Mt 2 not including probe Input RC Product 20 ws 05 nol including probe BNC connector accepts most TEKTRONIX probes P6065A probe recommended 10X Probe Calibrator Output Voltage 1000 V 0005 V or 0995 to 1005 V OPTION 4 TAPE T W SYNC Input NTSC Syncs lo either a standard negative going composite sync pulse of 35 V lo 45 V in amplitude or a 240 Hz negative going tape recorder pulse 15 V to 4 5 V in amplitude 2 083 ms in widlh and 4 166 ms in
139. nd 1485 only Range At least 20 UNCALibrated Indicator Front panel lamp indicates when the control is in a position other than detent SLOW SWEEP Option 7 Duration 4 to 12 seconds variable with front panel control Indicator Front panel indicator lit when slow sweep is operating but not actually running RGB YRGB Staircase Input Approximately 12 volts for 12 7 divisions of deflection DC signal levels plus peak ac not to exceed 12 to 12 volts maximum ac signal level is 12 volts peak to peak Sweep length RGB 2 FIELD 27 to 33 of normal sweep 10 us DIV 27 to 33 of normal sweep 5 us DIV 27 to 33 of normal sweep YRGB 2 FIELD 20 to 25 of normal sweep 10 us DIV 20 to 25 of normal sweep 5 us DIV 20 to 25 of normal sweep Sweep Repetition Rate 2 FIELD Field rate of applied video 5 or 10 us DIVision Line rate of applied video Staircase is positive going EXTERNAL HORIZONTAL INput Sensitivity 5 volts 10 division Linearity 1 Dc coupled positive going from OV Crt is unblanked with no provision for external blanking or unblanking Input Impedance Approximately 10 kilohms REV A SEP 1980 Specification 1480 Series SN B060000 up Table 4 6 cont Characteristic Performance Requirement Supplemental Information WAVEFORM COMPARISON LOCATE Range Will place location index
140. ne bar In both these cases the amplitude of the pulse is measured with respect to the midpoint of the line bar Where line time luminance distortion is present which is not untypical in long distance video transmission systems it is important to measure with respect to the bar s midpoint This is recognized in CCIR CMMT and other standard measuring procedures The usual measurement procedure is to adjust vertical gain so that bar midpoint equals 1 00 CCIR scale or 100 IRE units for NTSC signals and then measure the amplitude of the pulse At best this is an estimating process and involves the intermediate step always subject to error of setting gain correctly In Figure 1 pulse to bar ratio 0 965 chromi nance to luminance gain inequality 412 596 Figure 1 3 12 A far more accurate faster and convenient procedure dis penses with critical gain setting of bar midpoint to the grati cule and offers a direct comparison of pulse to bar mid point amplitudes This is shown in Figure 2 Such displays are especially useful when either high pre cision in measurement is desired or where exact equaliza lion is being made on circuits Some laboratory oscilloscopes could provide such a display by the well known double triggering mode In his book Television Measurement Techniques L E Weaver says greater accuracy is obtained in measurement of K Pulse to bar if the waveform monitor can be double tri
141. ng it in eyes or mouth wash hands after using silicon grease Power Transistors The power transistors that are heat sinked to metal parts of the 1480 Series Waveform Monitor are mounted with silicon grease 4 CAUTION Do not service or make internal adjustments to Mid Aii id accro dnd cines For continued fire hazard protection replace p giving p mains fuse with the type and rating listed on present the instrument rear panel and in the electrical parts list Avoid live circuits Electrical shock hazards are present CAUTION in this instrument especially in the power supply primary circuits fuse holder power switch and transformer Read the soldering instructions in SECTION 7 primary terminals the high voltage for crt operation and before attempting to solder on the circuit the 140 V supply to the Horizontal Output circuit board boards contained in this instrument 1480 Series SN B060000 up 2338 00 Fig 1 1 1480 Series Waveform Monitors showing both rackmount and cabinel models vi e PART 1 OPERATING INFORMATION INTRODUCTION This manual is divided into two parts The first part OPERATING INFORMATION is designed for use by anyone who needs to know how to operate a 1480 Series Waveform Monitor Part two SERVICE INFORMATION contains the information necessary to maintain the accuracy of a 1480 Series Waveform Monitor Part two should only be used by qualified service personnel servicing exposes pe
142. nnector Terminate the VIDEO INPUT A loop thru connector with the termination that is normal ly connected to the Unknown Arm of the return loss bridge d Checkthatthetest oscilloscope amplitude is 2 5 mV or less e Repeat the test for the VIDEO INPUT B and EXTERNAL SYNC A and B inputs f Connect the return loss bridge Unknown Arm do not terminate to AUX VIDEO IN AUX VIDEO OUT and PIX MONITOR OUT connectors in sequence while per forming part g g Check for a test oscilloscope amplitude of 11 mV or less at each of the connectors mentioned in part f Options The remaining steps in this procedure check the performance of option circuits beginning with Option 1 X10 Probe Input Each Option is identifed individually Option 1 X10 Probe Input Additional Equipment Required 1 10X Passive Probe For example P6105 Tektronix Part Number 010 6105 01 2 One 50Q feed thru termination Tektronix Part Number 011 0049 01 34 Check X10 PROBE GAIN Range a Compensate the 10X probe using the test os cilloscope vertical amplifier and calibrator b Move the 10X probe to the 1480 Series X10 PROBE INPUT Plug the probe tip into the CAL OUTPUT connec tor Switch the INPUT selector to PROBE and press the CAL and DC RESTORER SYNC TIP pushbuttons Rotate PROBE GAIN to its extremes and check for 1 V 10 and 10 at the respective ends of the control c Adjust X10 PROBE GAIN fora 1 volt display height 5 11 Perfor
143. nto the screen Note that the VITS and VIRS are displayed only at the start of the sweep when 2 fields are displayed in the All Fields mode Figure 2 shows the display of line 17 and 18 VITS plus the VIRS on line 19 Figure 2 Lines 17 18 VITS and 19 VIRS from each field Comparative Distribution System Analysis It is relatively easy to assess the distortion of an entire distribution system by using for example K rating of the VITS added at the point of origin However this does not localize individual problems in the system While not new the idea of inserting test signals at different points in the system and comparing them takes on a new dimension when the test signal can be directly overlaid for comparison rather than make tedious measurements with the graticule The All Fields display mode makes it possible to overlay the same line in both fields in order to compare waveform distortions which have occured over the entire system and those which arose in only a portion of the system REV A SEP 1980 POINTOF ORIGINATION WITH VITS Application Notes 145U Series SN BUOUUUU UDp Ib POINT OF REINSERTION MONITORING POINT FIELD 1 VITS Figure 3 VITS insertion for distribution system analysis This display mode opens up an interesting test method for distribution system analysis All that is required in addition to the display is a method to insert on the same line of the opposite field the iden
144. o jitter can be measured Heretofore this has nol been possible on a Waveform Monilor A 1480 Series Waveform Monitor operating in the 15 line mode gives a display of very nearly one millisecond of picture signal in either a 525 60 or 625 50 system This is a convenient time frame in which to make time base jitter measurements Select the 15 line 10 usec div display set the sync selector to internal AFC on and magnify the display to observe the leading edge of sync Any lime base instability will be readily apparent This measurement is particularly useful in applications where a mechanical scanner is used to reproduce video such as a quadruplex or helical scan videolape recorder By win dowing down through the field mechanical problems causing instabilily will be readily apparent Figure 15 shows jitter in the playback signal of a helical scan VTR caused by a dirty head drum bearing Figure 15 Time base jitter of a helical scan VTR The one millisecond time frame of the 15 line display is convenient for this type of measurement Transmitter Measurements The 1480 Series of Waveform Monitors provides the capability for all the usual transmitter measurements made with a Wave form Monitor and the unique Z axis signal gating provided to a vectorscope allows some unusual distortions sometimes Application Notes 1480 Series SN B060000 up found in television visual transmitlers to be observed One of the most apparent of th
145. odels Return Loss Greater than 46 dB to 5 MHz Table 4 4 SYNCHRONIZATION Option 4 amp 5 Video Tape Recorder Tone Wheel Sync Characteristic Performance Requirement Supplemental Information Tape Tone Wheel Sync NTSC 525 60 All Performance Requirements listed in Table 4 3 apply pulse polarity Negative repetition rate 240 Hz pulse period 4 166 ms pulse width 300 us pulse amplitude LL 4Vto15V PAL 625 50 pulse polarity Negative repetition rate 250 Hz pulse period 4 0 ms pulse width 300 us pulse amplitude 4Vto 15V Table 4 5 SYNCHRONIZATION Option 7 Slow Sweep Characteristic Performance Requirement Supplemental Information SLOW SWEEP Triggering Signal APL change from 10 or Front panel selectable less to 9096 for either or level change Sensitivity 400 mV to 2V peak to peak composite video with APL change Rate 0 2 Hz or more Free runs at rates less than 0 2 Hz or with no triggering signal Input Internal or External REV A MAY 1980 4 7 Specification 1480 Series SN B060000 up Table 4 5 cont Characteristic Performance Requirement Supplemental Information 50 60 Hertz Squarewave Triggering Frequency Range From less th
146. ond field of a normal 2 FIELD display HORIZONTAL POSITION AINE SELECTOR wb iP B Right front section cabinet model 2338 16 Fig 2 2 Horizontal control locations for rackmount left and cabinet model right REV A SEP 1980 2 5 Operating Instructions 1480 Series SN B060000 up 20 LINE SELECTOR Provides three modes of line selection to view any line in any field The line or lines selected are intensified in the 2 FIELD display The dark gray OFF button turns the LINE SELECTOR off DIG Provides positive digitally controlled line selec tions from the vertical interval of selected fields to start the line rate sweeps Selects the ninth through the twenty second line of each field VAR Selects single lines from the displayed fields with a multi turn potentiometer While in the 2 FIELD mode the selected line is intensified by a bright up strobe When the DISPLAY switch is set to 10 us DIV or 5 us DIV the display starts with the selected line 15 LINES Performs the same as the VARiable mode except the strobe is fifteen lines wide In the line rate displays the selected fifteen lines are overlaid on each other This is used to display headrotation of a quad head video tape recorder 21 IN EXT SYNC Selects source for Horizontal Syn cronization INT Derives sync information from incoming video signal that is being displayed EXT Derives sync information from composite signals ap
147. or systems employing the 10T pulse is accordingly 100 ns Baseline lobes corresponding to the full line portion of the dia gram show a chrominance lag termed positive by convention Ye OR Y 3 8 The broken lines denote a chrominance lead that is a negalive error B When no 1478 Calibrated Chrominance Corrector is avail able it is still possible to make a measurement of the chromi nance luminance gain and delay inequalities but with greatly reduced accuracy This method depends upon the fact that these quantities are calculable if the amplitudes of the two lobes into which the pulse baseline is deformed as a result of the distortion are individually known Consequently one sets the black level of the signal under test along the 0 3 graticule line and adjusts the gain until the peak of the 20T pulse just touches the 1 0 line this normalizes the pulse amplitude The display is then shifted vertically so that black level now lies along the 1 0 grati cule line when by shifting the trace horizontally the amplitudes of the two lobes can be read from the upper graduated scale Figure 4b Figure 4b Measurement of baseline lobes for use with the nomogram This pair of values denoted Y and Y respectively is trans ferred io the attached nomogram from which the chrominance gain and delay inequalities are read The table of diagrams inset should make the polarities of the distortions clear Note that the nomogram is cal
148. ot Pulse Overshool and Pulse Ringing 0 5 of applied pulse amplitude 25 s Bar Tilt lt 05 Field Square Wave Tilt 1 Pulse to Bar Ratio 0 99 1 to 1 01 1 or 099 to 101 1 Non Linear Waveform Distortion Differential Gain Displayed 0 5 at any APL AUX VIDEO OUT and PIX MONITOR OUT 0 25 at any APL Differential Phase AUX VIDEO OUT and PIX MONITOR OUT 0 25 at any APL DC RESTORER Mains Hum Attenuation Slow lt 10 Fast 26 dB Shift caused by Presence or Absence of Burst 1 IRE or 7 mV Return Loss With 75 Termination INPUT A or B gt 40 dB DC to 5 MHz AUX VIDEO IN AUX Video OUT or PIX MONITOR OUT gt 34 dB DC to 5 MHz Vertical Overscan for 1 V Peak lo Peak Com posite Video Signal all specifications are valid al 1 0 0 5 and 02 volts FULL SCALE and any verlical position setting to 5 MHz Calibrator Accuracy 1 V 0295 714 mV and 700 mV 05 Timebase Accuracy and Linearity 5 ys DIV and 10 4s DIV Accuracy Over Center 10 Div 1 Linearily Overall 1 Magnified Timing and Linearity For center 10 divisions of unmagnified sweep 2 accu racy 2 linearity 2 FIELD Sweep Length and Linearily 127 div 05 div FIELD SELECTOR Positise selection of ODD 2 amp 4 or EVEN 1 amp 3 in 525 60 Systems Display Slarts on selected field Positive selection of 1 2 3 or 4 or 1 amp 3 2 amp 4 in 625 50 Systems Display starts on selected field REV A SEP 1980
149. p The DC RESTORER is inhibited in DIFFD STEPS because the recovery of the differentiated sync pulse is not complete by either sync tip of back porch time The BANDPASS filters do not pass any dc or low frequency signal components so while the DC RESTORER still operates it does not affect the display Using the AUX VIDEO IN and AUX VIDEO OUT The AUX VIDEO OUT jack on the rear panel provides an unfiltered output internally terminated in 75 Q The AUX VIDEO IN is a 75Q internally terminated input that provides input access to the vertical system following the filters These two access points can form an external loop around the filters and measurements or corrections can be made in this loop for example using a chrominance to luminance delay corrector without disturbing the input signal An advantage of this function is the ability to compare a uncorrected signal with the corrected signal by switching between the AUX VIDEO IN and FLAT position of the RESPONSE switch The AUX VIDEO OUT is also one end of an impedance converting network The other end is the X10 PROBE input available as an option The signal acquired with the probe is processed in the same circuits as a video input The AUX VIDEO OUT is internally terminated in 75 Q making it compatible with the rest of the video system The signal acquired with the probe can then be routed through AUX VIDEO OUT to adisplay of measurement device such as a vectorscope Using
150. perimposed on an oscilloscope display for identification of selected lines The LINE STROBE OUT can also be used as a form of delayed gate to trigger some other unit at the selected line Using DIRECT and AFC SYNC DIRECT SYNC uses a wide band trigger circuit that accepts and processes low frequency signals as well as line rate sync AFC SYNC uses a narrow band trigger circuit that is limited to 15 75 kHz 200 Hz but atthe same time is relatively immune to noise Noise caused jitter can be reduced by using the AFC mode enabling the user to view a more stable waveform display REV B SEP 1980 Operating Instructions 1480 Series SN B060000 up Using EXT SYNC The EXT SYNC function is useful when viewing a non composite video signal such as might be acquired through the optional X10 PROBE input The sync signal used must lock both the waveform monitor and the unit under test A stable display can be obtained in the presence of small amplitude signals assuming the availability of at least 200 mV of composite sync to lock both the waveform monitor and the signal source Using EXTERNAL HORIZ IN The EXTERNAL HORIZ IN is provided for signal input access in case some special sweep rate is required A five volt ramp will generate a 12 7 division trace Input impedance of this circuit is about 10 kQ Unblanking for External Horizontal operating mode is shipped from the factory in a disabled condition An internal wiring change i
151. period PAL Syncs to negalive going 200 Hz lape recorder pulse 15 to 45 V in amplitude 2 5 ms in width and 5 ms in period Mains Voltage Ranges 100 VAC 110 VAC 120 VAC 200 VAC 220 VAC 240 VAC 10 Fre quency 48 Hz to 62 Hz Max Power Consump tion 75 W OPERATING TEMPERATURE O C to 50 C Dimensions and Weights 1480 C Series 825i 21cm 850i 216cm 1695in 430cm 215b 981kg 2851b z415 b z188kg Depth Nel Weight Domestic shipping weight Exporl packed weight Two 1480 C Series Wavelorm Monitors can be mounted side by side or one mounted alongside an associated picture monitor in a slandard 19 inch rack or console 1480 R Series Height 525in 133cm Width 190m 482cm Rack Depth 180m 457cm Net Weight 2461b 112kg 531lb 24 1 kol Domestic shipping weight z7511b 34 1 kg lExport packed weight Instrument fits standard 19 inch rack ORDERING INFORMATION 1480C NTSC Waveform Monitor 1480R NTSC Waveform Monitor 1481C PAL Waveform Monitor 1481R PAL Waveform Monitor 1482C PAL M Waveform Monitor 1482R PAL M Waveform Monitor 1485C PAL NTSC Dual Standard Waveform Monitor 1485R PAL NTSC Dual Standard Waveform Monitor Option 01 1 megohm 20 pf probe input probe not included Suggested Probe P6065A 10X Probe 6 ft Order 010 6065 13 9 ft Order 010610505 Option 02 With carrying Case Cabinet Version Only Option 03 With Blank
152. play facilities provided on the 1480 Series of waveform monitors have made it possible io produce a new 625 line graticule enabling a full range of video waveform measurements to be carried out with a minimum number of manipulations consequenily simplifying operational procedures In view of the growing importance of in service measurements its design has been based upon the international insertion test signal on line 17 but it can also be used for example with the U K national insertion test signal on line 19 A clear and uncluttered graticule which is extremely simple to use has been ensured by functional planning and by the omis sion of all superfluous information For instance the K factor limits have been restricted as far as practicable to a single value of 596 chosen because it may be regarded broadly as a dividing line between distortions which are subjectively acceptable and those which rapidly become increasingly intolerable It is also just slightly greater than the limit specified for the overall distor tion in a high qualily television chain including one main trans mitter1 Nevertheless this has not resulted in a loss of reading accuracy since the distortionless windowing facility of the 1480 Series means that the vertical gain control can be relied upon as a simple and convenient way of changing the basic tolerance value by a series of known factors i e the one diagram serves for 596 2V2 96 and 196 limits at the turn
153. plied to the rear panel A or B input 22 AFC DIRECT SYNC Selects sync processing AFC Phase locks the internal oscillatorto incoming line sync This mode offers more noise immunity about 8 dB jitter reduction than direct However jitter pre sent in the signal can be seen more readily in AFC mode This mode displays every line of incoming video including those with missing sync pulses at least ten consecutive lines before loss of lock As long as the incoming line frequency is within 200 Hz of 15 750 Hz the phase locked loop will provide a stable display Otherwise the sweep free runs DIRECT Provides a triggered display for every sync pulse received This mode will operate on low rep rate signals and up to 20 kHz line frequencies This mode will not display lines with missing sync pulses After a long period of time without a trigger reference sweep control will revert to the internal oscillator and free run until a new sync pulse arrives 2 6 23 WAVEFORM COMPARISON Selects a time overlay mode in the 10 uis DIV and 5 us DIV sweep rates useful for comparing most amplitudes within complex waveforms LOCATE Positions the comparison break point on the 10 us DIV and 5 us DIV displays provided that the OVERLAY control is out of the OFF detent position The comparison break point a small gap in the trace will be positioned at the right side of the sweep when the LOCATE control is near its clockwise end OVE
154. puts DC CPL D INPUT A and B 15 V DC Peak AC AUX VIDEO IN 1 5 V DC Peak AC Maximum Output DC Voltage AUX VIDEO OUT and PIX MONITOR OUT into 75 9 0 5 V DC Common Mode Rejection Ratio A B 60 Hz gt 46 dB 15 kHz gt 46 dB 4 43 MHz gt 34 dB Frequency Response FLAT including INPUT A or INPUT B Through AUX VIDEO OUT or PIX MONITOR OUT from 50 kHz Reference 50 kHz to 5 MHz 0 5 5 MHz lo 10 MHz 0 5 3 IRE Conforms to IRE 1958 standard 238 1 Atlenualion al 443 MHz gt 22 dB LOW PASS Attenuation 14 dB 500 kHz and above 3 58 MHz 1 of FLAT at 3 58 MHz 3 dB down at 3 1 lo 3 4 MHz and 3 8 lo 40 MHz 4 43 MHz 196 of FLAT at 4 43 MHz 3 dB down at 3 9 lo 4 1 MHz and 4 7 to 4 9 MHz DIFF D STEPS Per mils amplitude comparisons of risers on stair slep signal with automatic gain increase of 5 times atlenuation lt 2 dB from 0 4 to 0 5 MHz attenuation 20 dB al 15 kHz and 2 MHz at tenualion 40 dB at 3 58 MHz and 4 43 MHz Linear Waveform Distortion Pulse Preshoot Pulse Overshool and Pulse Ringing lt 0 5 of applied pulse amplitude 25 ws Bar Tilt 0 5 Field Square Wave Till lt 1 Pulse to Bar Ratio 0 99 1 to 1 01 1 or 0 99 to 1 01 1 Non Linear Waveform Distortion Differential Gain Displayed 05 at any APL AUX VIDEO OUT and PIX MONITOR OUT 0 25 at any APL Differential Phase AUX VIDEO OUT and PIX MONITOR OUT 0 25 at any APL DC RESTORER Mains
155. r such as the 149A NTSC Test Signal Generator 148 PAL or 148 M PAL M Insertion Test Signal Generator The test methods outlined here are covered in detail in Television Products Application Notes 11 12 and 20 Copies of these Application Notes are in Section 3 of this Instruction Manual Best results will be obtained when a composite test signal either full field if available or vertical interval is used This procedure is not a complete performance test but is a useful tool in determining if the waveform monitor is partially or totally operable Section 5 of this manual contains a thorough perfor mance test which should be used for incoming inspec tions or determining accuracy of calibration Hookup Connect a video signal to the A VIDEO INPUT connector Terminate 75 Q the other loop thru con nector 1 Vertical Gain and Calibrator Depress all dark gray pushbuttons Set vertical INPUT to a A DC VOLTS FULL SCALE to 1 0 and RESPONSE to FLAT Adjust INTENSITY FOCUS and SCALE ILLUM for a comfortable viewing level with the SCALE ILLUM knob pushed in While keeping the OPER pushbutton in depress the CAL pushbutton Check for the display in Fig 1 2 Leave both the OPER and CAL pushbuttons in and depress the SYNC TIP pushbutton Check for the display in Fig 1 3 Push down the OPER pushbutton this releases the CAL pushbutton Adjust the front panel GAIN screwdriver adjustment if necessary for a 1 volt peak to p
156. r comparison with the VTR head noise The video head of interest in selected by observing the picture monitor The noise generator is then adjusted to match the head noise The 15 line display mode allows excellent accuracy for this comparison by giving a bright stacked display of all 15 lines rather than trying to evaluate one line as was previously done This improved resolution provides greater accuracy as well as the increase in brightness It is not necessary to correctly adjust the female tape guide before making the head signal to noise measurement because accurate guide positioning is not necessary to this measure ment Each head can be checked and the results compared VIDEO IN PICTURE MONITOR OUT PICTURE MONITOR Figure 6 Equipment connections for head by head noise measurement Radical differences in signal to noise ratio between heads may indicate that the headwheel has reached the end of its useful life This is especially true in production houses where the same machine is used for playback in productions requiring multiple generations Each generation will be more noisy than the former and the end result may have unacceptable noise banding from just one noisy head This measuring technique will determine whether the head should be replaced before 3 22 expensive studio production time is wasted Figures 7 through 10 show the results of this noise measuring technique on the headwheel of a typical VTR us
157. r of the front panel The novel circuitry involved makes it possible to overlay ihe even and odd fields to display a single line pair of adjacent lines or both fields displayed as a single field in the 2 FIELD DISPLAY mode Using this display technique opens up an outstanding test method for distribution system analysis All that is required in addition to the ALL FIELDS display is a method to delete the original Insertion Test Signal on one field and reinsert an iden tical test signal Precautions must be taken that the outputs of any Insertion Test Signal generators used for this type of mea surement are as closely matched as current technology permits In addition the coincidence of the Insertion Test Signals is extremely important The TEKTRONIX 148 Insertion Test Signal Generator has a front panel screwdriver adjustment labeled INSERTION DELAY that may be adjusted for coincidence Matching generator is in itself an excellent use of the 1480 Series overlayed fields display with one generator inserting in even field interval while the other is inserting only in the odd field intervals For purposes of illustration the United Kingdom Insertion Test Signal 1 lines 19 and 332 is used and a determination as to which line will traverse the entire system and which will be deleted and subsequently reinserted has to be made Arbitrarily for purposes of illustration Line 19 even fields is the system reference while Line 332 odd fields
158. rate Use either a 100 or 200 nsec time base and check for duration of each cycle of burst This is a very accurate method to verify or calibrate see 1480 Series Waveform Monitor Instruction Manual the 1480 time base withoul special test equipment The discussion of test methods in this application note points out that proper design of the graticules for waveform monitors promoles versatility and ac curacy The new Graticule A used with the 1480 Waveform Monitor provides great versalility and accuracy without clutter a feature operating personnel will appreciate Some early 1480 Series Waveform Monitors including 1485 Dual Slandard models may not be equipped with this graticule If you desire an ex ternal version of this graticule contact your nearest TEKTRONIX field office or representative for assistance REV A SEP 1980 12 75 Application Notes 1480 Series SN B060000 up as TEKTRONIX E committed to technical excellence Copyright 1975 Tektronix Inc All rights reserved Printed in U S A Foreign and U SA Producls of Tektronix Inc are covered by Foreign and U S A Patents and or Patents Pending Information in this publication supersedes all previously published material Specification and price change privileges reserved TEKTRONIX SCOPE MOBILE TELEQUIPMENT and AX 3264 are registered trademarks of Tektronix Inc P O Box 500 Beaverton Oregon 97077 Phone Area Code 503 644 0161 TWX 910 467 87
159. rator com posite video through a 75 Q termination to the VIDEO INPUT A connector b Adjustthetelevision test signal generator amplitude and APL for a 1 volt display 5 8 c Setthe VOLTS FULL SCALE selector to 0 5 and add the 2X Attenuator in series with the 75 Q termination d Check for a display amplitude of 1 volt 3 e Set the VOLTS FULL SCALE switch to 0 2 and replace the 2X Attenuator with the 5X Attenuator f Check for a display amplitude of 1 volt 3 22 Check Horizontal Limiters a Connect the video signal source to the VIDEO INPUT A connector b Set the 1480 Series RESPONSE switch to FLAT DISPLAY switch to 10 us and MAGNIFIER to 1 us Div Rotate the HORIZONTAL POSITION control throughout its range c Check that the trace is not visibly limited or folded back on screen at any point in the range of the HORIZON TAL POSITION control 23 Check Magnifier Registration a Set the DISPLAY switch to 2 FIELD and center the display using the HORIZONTAL POSITION control b Set the MAGNIFIER control to X50 and rotate the HORIZONTAL POSITION control to set the last field sync pulse to graticule center c Set the MAGNIFIER control to OFF d Check that the last field sync pulse is within 0 5 division of graticule center 24 Check Horizontal Gain and Timing a Disconnect the composite video and connect the time mark generator to the 1480 Series VIDEO INPUT A connector Setthe time mark generator
160. ries with the cable a variable network which is then adjusted until the output waveform is judged 1o have a sufficiently low degree of dislortion This latter method is very fast and economical since the result is obtained immediately and without compulation It also has the great advantage that the effect of any small residual errors in the fit of the equaliser is automalically minimised a benefit which could only be achieved by the first method with the aid of a complicated compuler program Principle of Variable Corrector In general one would like to employ constant resistance net works for equalization purposes since these may be inserted into a circuit of the same impedance without mismalch and one is sure of obtaining the planned overall response Unfor tunately even in their simplest forms they are quite complicated networks to make variable since in every instance a pair of arms has to be changed simultaneously so as to maintain the con stant resistance property However there is an extremely useful and largely neglected Simple relationship between the arms of a constant resistance equaliser and the two terminal network which when inserted between a pair of equal resistances gives the same insertion loss characteristic This should be clear from the diagram Figure 3 Now the AUX VIDEO circuit in the 1480 Series provides just the requisite condition for the use of a two terminal network as an equaliser that is a pair o
161. riz Frequency Range 20 kHz Maximum Jiller with Respect lo Input Sync 12 ns input Composite Video or Compcsite Sync from a 140 series Generator 20 ns Variable APL 20 ns Variable APL amp 4 V rms Hum 90 ns Vanable APL amp 4 V Tum 36 dB White Noise EXTERNAL HORIZ IN Sensitivity 0 5 V div Linearity 1 RGB YRGB J9036 RGB Sweep Length Inter nally selected for A normal sweep YRGB Sweep Length internally selected for 1a normal sweep WAVEFORM COMPARISON LOCATE Range suf ficient to place LOCATE indication any place on 5 us DIV or unmagnified 10 s DIV sweeps OVERLAY Range sufficient to overlay any se lected portion of 5 s DIV or unmagnified 10 1 DIV on any other portion LINE STROBE OUT Strobe output of line or lines selected by VARIABLE 15 LINE o DIGI TAL line se ector modes and the DISPLAY switch TTL amplitude ac coupled Time Con stant 1 pF 10 kt OPTION 1 10X Probe Channel Scale Factor adjustable to 1 V peak to peak equivalent display height GAIN Range 10 Gain to AUX VIDEO Unity 3 with gain adjusted for 1 V peak to peak equivalent display height Till 5 on 50 Hz square wave High Frequency Response 195 25 Hz to 5 MHz 3 5 MHz to 10 MHz Referenced to 50 kHz Differential Phase 025 at any APL Dilferen tial Gain lt 0 25 at any APL Input Resistance 1 Mt 2 not including probe Input RC Product 20 ps 05 not including probe BNC connector accepts mo
162. robe input probe not included Suggested Probe P6065A 10X Probe 6 11 Order 010 6065 13 9 ft Order 010610505 Option 02 With carrying Case Cabinet Version Only Option 03 With Blank CRT Option 07 Slow Sweep Option 08 Adds capability of recognizing four field sequence of SECAM 1481C 1481R 1485C 1485R only TEKTRONIX Automatic Correction Products are also available for 525 60 NTSC systems Tektronbc COMMITTED TO EXCELLENCE P O Box 500 Beaverton Oregon 97077 US 3 15 Application Notes 1480 Series SN B060000 up application notes Tektronix COMMITTED TO EXCELLENCE wuwuuuuygunnumumpumuluuuuu Superimposing Alternate Field ITS to Improve In Service Testing Since their introduction the use of Insertion Test Signals for in service measurement has revolutionized television distribu tion system measurement techniques For the first time it be came possible to test a distribution system while it was in use The new TEKTRONIX 1480 Series Waveform Monitor is espe cially designed to even further these techniques One of the major innovative display modes added to the 1480 Series is ALL FIELDS which superimposes all or part of alternate fields This new feature presents some very distinct advantages 1 Simultaneous viewing of all four International Insertion Test Signals or other selected interval lines 2 Comparison of ITS signals applied at separate points 3 An in service method of displa
163. rsatile feature may be developed to go along with the demands of ever more sophisticated measurements Simultaneous Viewing of VITS With the TEKTRONIX 1480 Series Waveform Monitor s All Fields display mode the Vertical Interval Reference Signal VIRS two or four VITS or a combination of both VITS and VIRS on both fields can be viewed simultaneously The Dis play and Magnifier switches determine how many vertical interval lines are displayed To display one line from each field start by setting the DISPLAY switch to 5 us DIV to provide a single tv line 1H display Activate the line selection by depressing the DIG digital pushbutton and set the LINE SELECTOR for the desired line Then to obtain the All Fields display push in both FIELD selection pushbuttons For PAL equipped instru ments depress the ALL FIELDS pushbutton located in the lower right corner of the front panel Setting the DISPLAY switch to 10 4s DIV provides two successive lines 2H from each field The line selected by the LINE SELECTOR setting and the one following it are displayed See Figure 1 3 40 Figure 1 Two VITS lines from each field A novel way to display all signals inserted on lines 17 through 20 of both fields is to set the DISPLAY switch to 2 FIELD and set the MAG to X50 Depress both of the FIELD selection pushbuttons or in the case of PAL instruments push in the ALL FIELDS pushbutton and horizontally position the start of the trace o
164. rsonnel to hazardous voltages Section 1 1480 Series SN B060000 up UNPACKING AND INCOMING INSPECTION The 1480 Series Waveform Monitor operates from a single phase power source with one of the current carrying conductors neutral conductor at ground earth potential Operation from power sources where both current carrying conductors are live with respect to ground such as phase to phase on a 3 wire system is not recommended since only the line conductor has over current fuse protection within the instrument The 1480 Series Waveform Monitor has a 3 wire cord with a 3 terminal polarized plug for connection to the power source and earth ground The earth ground ter minal of the plug is directly connected to the metal chassis of the instrument For electric shock protection insert the power plug in a mating outlet with an earth ground contact Table 1 1 gives the conductor color codes of power cords used in Tektronix instruments TABLE 1 1 POWER CORD COLOR IDENTIFICATION Conductor Color Alternate Color Ungrounded Line Brown Black Grounded Neutral Blue White Grounding Earth Green Yellow Green Yellow Unpacking and Incoming Inspection 1480 Series SN B060000 up If a 3 to 2 wire adapter is used to connect the 1480 Series to a 2 wire ac power system be sure to connect the ground lead of the adapter to a conductor that connects to earth ground Failure to complete the grounding system m
165. rtion is easily assessed from the K rating of the line 17 field 1 composite test signal that has traversed the entire system and will show the total amount of distortion throughout the system The K rating of the line 17 field 2 composite signal provides a measure of the distor tion occurring between the reinsertion point and the monitor ing point When both fields are overlayed display the dif ference in the signals is the measure of the distortion occur ring between the origination and the reinsertion point FIELD 2 VITS Figure 4 VITS comparison a Line 17 VITS from both fields b Line 17 VITS trom field one c Line 17 VITS from field two CCIR Recommendation 473 Annex 2 525 line systems adopted 1974 REV A SEP 1980 3 41 Application Notes 1480 Series SN BO60000 up 20 100 Figure 5 a Comparison of 2T pulses from both fields 0 2 Volts Full Scale b Comparison of 12 5T pulses from both fields VIR Signal Comparison Another use of the All Fields display mode allows the com parison of in house generated VIRS which may be used as a reference waveform once it has been determined that the locally generated VIRS is within tolerance to the incoming program line VIRS Set the in house VIRS inserter to strip and reinsert on one field only Set the 1480 Series Wave form Monitor LINE SELECTOR to line 19 and depress both FIELD selection pushbuttons or the ALL FIELDS push button on PAL equiped instrum
166. s required to activate this unblank ing See note on diagram 9 2 13 Operating Instructions 1480 Series SN B060000 up OPTIONS The following portion of the Operating Instructions deals with customer ordered options If none of the options listed here are in the 1480 Series Waveform Monitor used with this manual disregard this part of the Operating Instructions OPTION 1 X10 Probe Operating Instructions The signal from the X10 PROBE INTPUT is inserted in the vertical system at the same point as signals applied to the A and B VIDEO INPUTS All front panel controls then have the same effect on the X10 Probe signal as they have on other signals Pressing the front panel CAL button provides a squarewave output at the CAL OUTPUT jack to be used for probe compensation Connect a 10X Probe from the X10 PROBE INPUT toa source of 1 volt peak to peak composite video Set the VOLTS FULL SCALE to 1 0 RESPONSE to FLAT INPUT to PROBE DISPLAY to 10 us DIV and MAG to OFF Press the DC RESTORER SLOW and BACK PORCH OPER EVEN FIELD SYNC INT and AFC LINE SELECTOR off buttons This will cause a 1 volt display Set the front panel controls to each position in turn and note that the effect is the same for the X10 PROBE signal as for normal operation OPTION 2 Carrying Case For Cabinet Models This option has no effect on the operation of the 1480 Series Waveform Monitor OPTION 3 Blank CRT This option is ordered for u
167. se to bar amplitude ratio of 1 equals 2 chrominance luminance gain inequality With X5 vertical expansion this small gain inequality or less is easily and accurately resolved Line time luminance nonlinearity is a measurement in which the relative amplitudes of the five differentiated step risers spikes are compared See Figure 6 The differentiation of the risers provides a sensitive measurement of non linear distortions affecting the luminance signal CCIR defines this distortion as 1 w where m equals the amplitude of the least spike and M the amplitude of the greatest spike In Figure 7 the time base foldback feature of TEKTRONIX 1480 Series is used to compare spike amplitudes Here the least amplitude spike and greatest amplitude spikes are over laid for easy comparison Line time distortion e g Tilt of the line bar can be very accurately measured by comparing the amplitude of any part of the line bar with its midpoint amplitude Here again the calibrated vertical expansion of TEKTRONIX 1480 Series combines with time base foldback to provide accurate reso lution of small distortions Figure 8 shows the line time distortion on bar top Utilizing the Tektronix developed time base foldback and calibrated X5 vertical expansion it is possible to resolve 0 2596 distortion or K 0 2596 Distortions as small as those cited above do not represent significant piclure impairments However a series of cas caded links ea
168. se with special graticules Operating instructions out of necessity will be generated by the user 2 14 OPTION 4and OPTION 5 VTR Tone Wheel Sync Operating Instructions With the 1480 Series Option 4 Waveform Monitor installed in an RCA TR70C operation is virtually automatic The TR70C provides external locking signals switching commands and input signals so that the Waveform Monitor displays the signal of interest The signal of interest is selected by pressing one of the Waveform Monitor Selector pushbuttons located on the TR70C panel below the Waveform Monitor For detailed instructions about using the Waveform Monitor in the TR70C see RCA Operation and Installation Manual 1B 32168 Some typical displays are shown in Fig 2 10 2 11 and 2 12 OPTION 6 124 Q Balanced Inputs Option 6 is a large scale modification of the 1480 Series Waveform Monitor and for that reason employs its own Instruction Manual Supplement Tektronix part number 070 2064 00 which contains complete operating instructions OPTION 7 Slow Sweep Slow Sweep uses triggering either from internal or external source Display mode is selected by the setting of the DISPLAY switch It can be set to TRIG PLRT triggering polarity which starts the triggered sweep on the transition from black or near black to white or near white or TRIG PLRT which is the opposite transition Sweep duration is controlled by a variable labeled VAR which provid
169. shipped disabled to avoid burning the cathode ray tube Aninternal jumper must be moved to enable See note on diagram 9 Direct acting Sync follows horizontal jitter so that jitter is not displayed the AFC mode displays any horizontal jitter Rear Panel The main video and external sync signal inputs are of loop thru design no internal termination and can be isolated from the chassis allowing for differential rejec tion of hum by the input stages Input connectors are available for RGB displays and external horizontal inputs along with an auxiliary video inputto the vertical amplifier Output connectors supply auxiliary video out a picture monitor video signal and a line strobe pulse coincident with the setting of the Line Selector Variable control and the digital Line Selector Also available is a connector mounting location for customized remote operating installation Operating Instructions 1480 Series SN B060000 up Graticules The graticule most applicable in the television system for which a particular model is intended is supplied internal to the crt Also included as standard accessories are several external graticules usually intended for specific measurements or to convert dual standard models from one line standard to the other A blank crtis available as an option External graticules are available in both NTSC and CCIR configurations in two pattern sizes One intended for normal viewing use is the sam
170. sources of error enter into this process There will be some uncertainty in fitting the calibrating waveform against the reference lines and a similar uncertainty when the video waveform is compared with them In addition the vertical gain will change by some finile amount between these two settings particularly when as often happens in practice they may be separated by relatively long periods of time The sum of these is the transfer error which of course is very appre ciably magnified when parallax is present Application Notes 1480 Series SN B060000 up None of these errors occurs in the method described above whose accuracy is impaired only by the tolerance range in the square wave amplitude itself and the inaccuracy of setting To take an example the square wave amplitude in the 1480 Series is defined within 0 2 and it has been shown above that the comparison error is probably not more than about 0 2 under suitable conditions The overall error is therefore likely to be only about 0 4 When one takes into consideration the fact that the convention al method does not permit the use of amplification to reduce the setting inaccuracy it is clear that the present method shows a very considerable advantage which is increased still further when an external graticule is in use and parallax errors are present in addition The principal drawback of the method is its dependence upon a reasonably distortion free signal While good si
171. ssible or at best estimations when performed in service are now accu rate and time saving Copyright 1977 Tektronix Inc All rights reserved Printed in U S A Foreign and U S A Products of Tektronix Inc are covered by Foreign and U S A Patents and or Patents Pending Information in this publication supersedes all previously published material Specification and price change privileges reserved TEKTRONIX TEK SCOPE MOBILE TELEQUIPMENT and P are registered trademarks of Tektronix Inc P O Box 500 Beaverton Oregon 97077 Phone Area Code 503 644 0161 TWX 910 467 8708 Cable TEKTRONIX More than 50 Subsidiaries Distributors around the world 5 77 3 18 AX 3076 1 REV A SEP 1980 CHARACTERISTICS Application Notes 1480 Series SN B060000 up SCALE FACTOR INPUT A and B 10 Volts Full Screen 1 3 mV 0 5 Volts Full Screen 15 mV 0 2 V F Screen 6 mV Ratio INPUT A to INPUT B 1 0 002 to 1 AUX VIDEO IN lo INPUT A 1 5 03 dB GAIN INPUT A to AUX VIDEO OUT 1 0 005 INPUT A to PIX MONITOR OUT 1 0 02 VARIABLE VOLTS FULL SCALE RANGE Input signals between 0 7 volls and 2 0 vols can be adjusted lo 1 volt equivalent display height Maximum Input Signal for inspecification op eration of AUX VIDEO OUT and PIX OUT AC CPL D INPUT A and B 20 V P P at any APL Display distortion 1 0 V P P al any APL if both AUX VIDEO OUT and PIX OUT are lerminaled for distortion Iree signal al those out
172. st TEKTRONIX probes P6065A probe recommended 10X Probe Calibrator Output Voltage 1000 V 0005 V or 0995 to 1005 V OPTION 4 TAPE T W SYNC Input NTSC Syncs o either a slandard negative going composile sync pulse of 3 5 V to 45 V in amplitude or a 240 Hz negalive going tape recorder pulse 15 V lo 45 V in amplitude 2 083 ms in width and 4 166 ms in period PAL Syncs to negative going 200 Hz tape recorder pulse 15 to 4 5 V in amplitude 25 ms in widlh and 5 ms in period Mains Voltage Ranges 100 VAC 110 VAC 120 VAC 200 VAC 220 VAC 240 VAC 10 Fre quency 48 Hz lo 62 Hz Max Power Consump tion 75 W OPERATING TEMPERATURE O C to 50 C Dimensions and Weights 1480 C Series 8 251n 8 50 in 16 95 in 21 5 Ib 285 b 2415 Ib Domestic shipping weight Exporl packed weight Two 1480 C Series Waveform Monitors can be mounted side by side or one mounted alongside an associated picture monitor in a standard 19 inch rack or console 1480 R Series 190 in 180 in 24 6 Ib 53 1 Ib 75 1 Ib Domestic shipping weight Export packed weight Instrument fits standard 19 inch rack ORDERING INFORMATION 1480C NTSC Waveform Monitor 1480R NTSC Waveform Monitor 1481C PAL Waveform Monitor 1481R PAL Waveform Monitor 1482C PAL M Waveform Monitor 1482R PAL M Waveform Monitor 1485C PAL NTSC Dual Standard Waveform Monitor 1485R PAL NTSC Dual Standard Waveform Monitor Option 01 1 megohm 20 pf p
173. tainly be the case in studio areas one can estimale the resolution of the meas urement to be about one tenth of a division say 0 1 dB This is good enough for some purposes However with the 1480 series the gain may be increased by up to five times with out distortion so that the resolution can be improved to a figure of about 0 02 dB which offers the possibility of very accurate measurements Figure 4 EE oer too iu Figure 4 Level 10 high X 5 gain The resolution obtained in practice is of course limited by the random noise level present in the signal under test That is in no way special to the present method but is perfeclly general Where the signal is noisy a useful improvement is possible by first passing it through a low pass filter which reduces the band width without unduly deforming the flat portions of the bar and the sync pulse although the accuracy will then depend upon a correct allowance being made for the insertion loss of the filter The amount of improvement obtained is a function of the char acter of the random noise With the 1480 Series a useful device is to alter the RESPONSE contro from FLAT to IRE which attenuates the higher video frequencies with very little distortion but does not affect the calibration of the instrument In more severe cases the use of the LOW PASS setting is permissible The marked improve ment which can be obtained in this simple way is very clearly shown in Figures 5a
174. termination k Rotate the DISPLAY switch to each position except EXT and check that the display does not change 39 Check Sync Stability a Set the 067 0621 00 Ext Sync Source switch to Ext Check for a stable display b Remove the cable from EXTERNAL SYNC A loop thru connector Check for an unstable display Replace the cable Return the 067 0621 00 Ext Sync Source switch to Int 40 Check Sweep Length a Set the RESPONSE switch to AUX IN Set the 067 0621 00 Ext Sync mode switch to Tone Wheel Check that the display does not flicker remains stable and is 12 5 div 0 5 div in length 41 Check Maximum Input a Remove the termination from the test oscilloscope vertical input Adjust the pulse generator for maximum output amplitude Check to see that the display is unchanged Option 7 Slow Sweep Additional Equipment Required One video signal source capable of generating a bounce signal For example TEKTRONIX 148 PAL 148 M PAL M or 149A NTSC Test Signal Generator 42 Check SLOW SWEEP Speed a Connect the output of the time mark generator to the 1480 Series VIDEO INPUT A connector Set the DISPLAY switch to SLOW SWEEP TRIG PLRT Apply 1 second time marks b Rotate the VAR DISPLAY control fully clockwise and check for five or less time marks per sweep c Rotate the VAR DISPLAY control fully counterclockwise and check for 12 or more time marks per sweep 43 Check SLOW SWEEP Trigger Polar
175. the entire system it will display maximum distortion and should be identified prior to the actual over laying When ALL FIELDS is selected any difference is imme diately apparent See Figure 4 Figure 4 a Insertion test signal through full system b insertion test signal reinserted c Signals a and b overlayed REV A SEP 1980 Once the ALL FIELDS display is obtained several options aside from the obvious visual comparison remain One compara tive K rating is especially valuable if the monitoring point is physically removed from the point of reinsertion allowing some degradation of both test signals Figure 5 shows K and K of the overlayed test signals note that both displayed signals are degraded and that three distinct pieces of information are available 1 Total distribution system distortion K rating of the Line 19 test signal 2 Distortion from the point of reinsertion to the monitoring point K rating of the Line 332 test signal 3 Distortion from the point of origin to the point of reinsertion difference in the K ratings Figure 5 a K of the overlayed ITS b K of the overlayed ITS 3 17 Application Notes 1480 Series SN B060000 up Observing Field Time Distortion It is normally not possible to observe field time distortion on an in service basis However with the ALL FIELDS display mode of the 1480 Series Waveform Monitor it can now be done with relative ease It should be not
176. tical test signal Precautions must be taken that the outputs of any test signal generators used for this purpose are as closely matched as current technology permits including the adjustment of VITS timing relative to sync The TEKTRONIX 149 149A NTSC Test Signal Generator has a front panel adjustment labeled INSERT DE LAY that is adjusted in this case for coincidence of both VIT Signals This matching of generators is an excellent use of the 1480 Series All Fields display with one generator inserting on one field and the other inserting on the opposite field For purpose of examination the composite test signal speci fied by the CCIR for international exchange of program material is substituled on field 2 line 17 for the VITS normally inserted on that line To further simplify this illustration the field 1 VITS will traverse the entire system while field 2 VITS are for this purpose being reinserted at some down stream point The technique is universal in that the size of the system under test can be anywhere from a studio to transmitter link to a transcontinental network By locating the 1480 Series Waveform Monitor downstream from the reinsertion point three distinct pieces of information are readily available 1 Overall system distortion 2 Distortion occuring between original insertion point and reinsertion point 3 Distortion occuring between the reinsertion point and the monitoring point The overall system disto
177. tive ease The uncluttered scale design and well thought out organizalion of this new graticule yield consistently accurate results with a minimum of control setting changes Graticule A Vertical Scales The vertical scale of this new NTSC composite graticule extends from 50 io 120 IRE Units in 10 IRE Unit increments In addition three sep arate 2 IRE Units div scales are provided at strategic locations for rapid precise measurements of key signal parameters A dashed line at 7 5 IRE Units or 7 596 is provided for use as a black level setup reference The right side scale for measuring trans mitter of modulation extends from 0 at the 120 IRE Unit line to 100 al the 40 IRE Unit line The 0 zero IRE Unit reference line which contains horizontal divisions is subdivided for measurement of time Horizontal Scales The horizontal refer ence line at 0 IRE Units is 12 7 divisions long Using the 5 s DIV time base the time base line is 63 5 usec 1H long The 10 us DIV time base provides a time base of 127 usec 2H This makes it possible to calibrate the 5 and 10 us DIV lime bases using the TV signal The 30 IRE Unit line contains nine 3 34 divisions which correspond lo one half of the period of a cycle of NTSC burst at 100 nsec div At 200 nsec div the divi sions or lick marks equal the period of one cycle of burst These relationships make it possible to accurately calibrate the 100 and 2
178. to 22 NTSC 9 322 to line 22 335 PAL line 9 272 to line 285 PAL M VAR Approximately line 20 of the selected field to line 8 of the next related field 15 lines ldentical to VAR excep 15 successive lines are displayed Sync AFC Horizontal frequency range is 15 75 kHz 200 Hz Max jitter with respect to input sync 10ns 30ns with 4 volts rms hum plus 36 dB white noise Direct Horizontal frequency lt 20 kHz Max jitter with respect to input sync 12ns 90ns with 4 volls rms hum plus 36 dB white noise OUTPUTS Line Strobe TTL amplitude pulse Pulse coin cident with line or lines selected by VAR 15 LINE or DIG modes of DISPLAY swilch Picture Monitor Output of incoming video wilh LINE STROBE added Oulput impedance is 759 Output adjusted to unity wilh respect lo A and B video input Aux Video Output of incoming video 75 oulput impedance Gain adjustable to unity wilh respect to A and B video input OTHER CHARACTERISTICS RGB YRGB Staircase Input Approx 12 volls for 12 7 divisions deflection RGB sweep length inter nally selected for normal sweep YRGB sweep length internally selected for Ya normal sweep length Mains Vollage Ranges 100 V ac 110 V ac 120 V ac 200 V ac 220 V ac 240 V ac 10 Frequency 48Hz to 62Hz Max Power Consumplion 75 W At factory 1480 preset lor 110 V ac 1481 1482 1485 preset for 220 V ac OPTION 1 10X Probe Channel Scale Factor 1 V 0 5 V
179. trument becomes available in application note form it will be distributed through mailings and later be bound into reprints In order to keep this manual current periodically check with a Tektronix Television Specialist or sales representative about any new Application Notes pertinent to this instrument Some of the Application Notes in this section were authored by renowned authorities in the field of video measurement Their topics include some new and highly accurate measurement techniques that are destined to become standards of the television industry Table of Contents Application Note Title 11 Measurement of Signal Level with the 1480 Series of Waveform Monitors 12 Operational 625 Line Measurements with the 1480 Series of Waveform Monitors 13 Time Base Fold Back A Novel Improvement Over Double Triggering for Video Testing 14 Superimposing Alternate Field ITS to Improve In Service Testing 15 Enhanced Video Measurement Capability Using the 15 Line Display of the TEKTRONIX 1480 Series Waveform Monitors 16 Verifying the Bruch Blanking Sequence 17 The Auxiliary Video of the 1480 Series of Waveform Monitors 20 A New NTSC Graticule For the 1480 Waveform Monitor 21 All Fields Display to Improve NTSC In Service Testing 3 1 Application Notes 1480 Series SN B060000 up application notes w TEKTRONIX TERN committed to technical excellence yu Uu uu WWW mn uuu The Measurement of Signal Lev
180. ttons are pressed individually 12 1 2 Hz Sweep rate 9 In Option 4 and Option 5 VTR T W Sync Input instruments the DISPLAY switch in 10 us DIV and 2 Field sweep enabled through J9034 using the MAG switch causes the display to shift about one field to the left 10 To prevent damage to the crt the unblanking for the External Horizontal display mode is disabled An internal wiring change is required to activate the unblank ing MEASUREMENT TECHNIQUES Using WAVEFORM COMPARISON The most obvious use of the WAVEFORM COM PARISON function is to check amplitude ratios such as pulse to bar measurement This measurement mode can be used on any line or pair of lines that can be displayed including lines selected in the LINE SELECTOR modes WAVEFORM COMPARISON is also useful in com paring amplitudes of the modulated packets on the linearity staircase signal Differential gain can be checked with the modulated staircase applied and the waveform monitor in the BANDPASS RESPONSE position and 0 2 VOLTS FULL SCALE By overlaying the last modulation packet on the first any differences can be easily viewed and measured Adjacent lines can be overlaid and amplitudes com pared using the 10 us DIV DISPLAY position Locate the break point at the line sync pulse in the center of the display and adjust OVERLAY control as necessary to overlay the two lines REV B SEP 1980 Using the Calibrator The calibrator signal can be set to one of
181. ude if neces sary Vertically set the blanking level on the graticule 0 IRE Unit reference line See Figure 8 Figure 8 Chrominance to Luminance De lay Inequality measurement C L Delay Inequality 200nsec If as in Figure 8 chrominance lumi nance gain inequality is negligible chrominance luminance delay inequality is easily measured by comparing the symmetrical sinusoidal baseline abbera tion to the special delay scale The plus to minus transition solid line is used with a positive chrominance delay chrominance lag while the minus to plus transition dashed line is for negative chrominance delay chrominance lead A full scale symmetrical transition such as the one in Figure 8 equals 200 nsec of delay inequality Since chrominance luminance delay inequality may be considerably less than 200 nsec the calibrated vertical expan sion of the 1480 Waveform Monitor allows two and five times resolution increase Setting VOLTS FULL SCALE lo 0 5 changes the delay scale to 100 nsec peak to peak 0 2 VOLTS FULL SCALE increases he delay inequality scale resolution to 40 nsec See Figure 9 Figure 9 Chrominance to Luminance De lay Inequality measurement with in creased gain C L Delay Inequality 40 nsec Luminance Non linearity Luminance non linearity is easily mea sured using the differentiated step display mode of the 1480 Waveform Monitor Position the composite waveform stair case to grat
182. uence takes place at the end of this field and the beginning of the next field Figure 2 shows field 4 followed by field 1 FIELD 4 selected Figure 1 3 26 REV A SEP 1980 HORIZONTAL POSITION WAVEFORM COMPARISON LOCATE OVERLAY Figure 3 Figure 3 shows the location of the switches and controls used in the following procedure The numbers associated with the controls correspond to the step in the procedure in which that control is used REV A SEP 1980 Application Notes 1480 Series SN B060000 up Verification Procedure 1 Set the DISPLAY switch to 2 FIELD 2 Depress FIELD 1 and 3 pushbuttons simultaneously 3 Depress 15 LINES 4 Adjust VAR LINE SELECTOR to place the intensified portion of the display on the interval between the two fields Turn the MAG switch to X50 6 Adjust the HORIZONTAL POSITION to place the interval at mid screen Reduce the INTENSITY until the brightened in terval is obvious Readjust the VAR LINE SELECTOR as necessary to display the interval and at least 2 lines on either side of the interval 7 Check for a burst on either side of the interval with a dis cernable flicker rate caused by a reduced repetition rate indicating the presence of the blanking sequence Even if the sequence appears to be in error proceed to Step 8 where each field is investigated individually so that the fault can be located 8 Depress the FIELD 4 pushbutton Check the display against t
183. us Frequency Response A simple technique for checking fre quency responses uses the multiburst signal to check for amplitude variations at the different frequencies See Figures 15a and 15b Care must be used in in lerpreting results of measurements made with the multiburst signal because it is not uncommon to note harmonic distortion on one or more of the bursts Even order harmonics cause inequality between positive and negalive peaks Therefore if the amplitude of only one of the peaks is measured incorrect results will be obtained Measure both the pedestal to positive peak and pedestal to negative peak to determine if even order harmonic distoration is present Odd order harmonic distortions affect 3 37 Application Notes 1480 Series SN B060000 up both peaks in the same manner causing the peak to peak amplitude to be either too high or too low The peak to peak amplitude depends on whether the 3rd harmonic can pass through the system High frequency phase shift of this 3rd order harmonic will cause the peak lo peak amplitude of the burst to be distorted Figure 15a Combination of Multiburst and Modulated Pedestal signals GRATA Figure 15b Amplitude Frequency Re sponse 3 dB down at 3 Mhz The multiburst signal shown in Figures 15a and 15b is the combined multiburst and modulated pedestal signal also described in CCIR Recommendation 473 Annex Il Vertically position the multiburst signal blanking l
184. xcept Opt 3 331 0393 10 1 NTSC Graticule B photo 1480 amp 1485 except Opt 3 331 0393 11 Optional Accessories A variety of optional accessories for use with 1480 Series Waveform Monitors is available from Tektronix Inc The following available through the nearest Tektronix Field Office or sales representative are the most commonly used optional accessories Tektronix Description Part No BNC Elbow male to female 103 0031 00 BNC T Connector 103 0030 00 75 Q 42 inch Cable BNC Connectors 012 0074 00 75 Q 300 inch 25 ft Cable BNC Connectors 012 0157 00 75 Q End Line Termination BNC Connectors 011 0102 00 75 Q Feed Thru Termination BNC Connectors 011 0103 02 Detailed descriptions and pictures of these and other optional accessories are in the Tektronix Television Products Catalog Unpacking and Incoming Inspection 1480 Series SN B060000 up QUICK OPERATIONAL CHECK It is possible to determine if the functions of the 1480 Series Waveform Monitor are operational without employ ing a full fledged Performance Test This check cannot take the place of the Performance Test that occurs laterin this Instruction Manual An accurate video signal with test signals in the vertical interval is all that is required to determine if the basic display functions of the 1480 Series Waveform Monitor are operational The source of this signal may be either a live video feed with ITS or VITS or a television signal generato
185. yellow and cyan bars See Fig 5 3 Color Bar b Set the RESPONSE switch to AUX VIDEO IN c Check the amplitude difference between the tops of the yellow and cyan bars it should be the same as that noted earlier 54 d Set the VOLTS FULL SCALE selector to 0 2 Posi tion the tops of the yellow and cyan bars to the top of the graticule then to the bottom of the graticule e Check for a difference of 7 5 mVorless between the yellow and cyan bars f Set the VOLTS FULL SCALE selector to 1 0 g Check the amplitude difference between the tops of the yellow and cyan bars it should be the same as that noted at the beginning of this step h Connect the leveled sinewave generator output through a 50 Q to 75 Q Minimum Loss Attenuator to the AUX VIDEO IN connector Set the leveled sinewave generator for a frequency of 50 kHz and an output amplitude of 1 volt 140 IRE for NTSC Do not change the leveled sinewave generator amplitude for the remainder of this step i Change the 1480 Series VOLTS FULL SCALE selec tor to 0 5 and vertically position the display so that the top of the display is at the 1 0 V or 100 IRE line Note because the vertical sensitivity is doubled the graticule scale is now halved making the major vertical divisions 50 mVorS IRE Minor divisions where they occur are now 5 mV or 1 IRE j Check auxiliary video input response according to Table 5 1A 0 5 VOLTS FULL SCALE 120 zen GRAT A 100
186. ying field time distortions Simultaneous ITS Methods of in service testing in common use all require accu rate Insertion Test Signals located on specific field blanking interval lines Because of th s requirement the International Radio Consultative Committee C C I R has established 4 lines for internationally defined test signals In addition lines are assigned and used for national test signals Because of their importance to the overall quality of television processing cir cuits ITS are being more closely monitored The 1480 Series Waveform Monitor ALL FIELDS display is an ideal method of observing these signals When used in the 10 4 second per divi sion 2 H sweep rate all four of the international Insertion Test Signals lines 17 18 330 and 331 can be viewed at once See Figure 1 Figure 1 All 4 international insertion test signals displayed simultaneously Comparing ITS It is relatively easy to assess the distortion of the entire distri bution system by K rating it with the Insertion Test Signal added 3 16 no 14 Figure 2 1485R Front Panel at the point of origin However this does not isolate individual problem areas Although not new the idea of inserting test sig nals at different points and comparing them takes on a new dimension when the test signal can be directly overlaid for com parison This display mode is selected through the ALL FIELDS selec tion located at the lower right corne

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