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HP 3780A User's Manual

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1. 5344 Y vG 32 215 A LY WHOS Da Eis ES edad SOM EZ i A TD OO 2883 Mis GP gaz 38 pg v1 zn ei 40483 135350 1 Pia ee ASYNIE 23 03383 4 e i Veraar 77 36123JBQ0 0 83 8345 53 351 N33 31i1vdj VOS C O e Ot 9 SC gZ 4262 0 6 vS5 Z 8 1 VO8LE IPPON 11 The data is not modified and the sequence 15 6 termined bv controls 7 8 and 9 oniy 18 the ERROR ADD position a fixed binary error rate of 10 is introduced into the generator sequence by producing 10 consecutive errors in every 1000 clock periods The ZEROS switch selects the number of zeros added to any pattern when the ZERO ADD posi tion of the ZERO ADD NORM ERROR ADD switch 10 is selected 3 8 GENERATOR FORMAT CONTROLS AND OUTPUT CONNECTORS Determine generator output format 12 13 14 15 16 17 The DATA FORMAT switch selects between bin ary and ternary data output formats The binary data formats RZ return to zero and NRZ non return to zero are available at both DATA O P 14 and DELAY DATA O P 15 connectors The ternary data formats AMI alternate mark inversion and CODE HDB3 or HDB2 options 101 and 102 8625 or 8325 selected with the rear panel CODE switch are available at the DATA O P connector 14 only The CODE switch on the rear panel selects HDB3 or HDB2 code formats foptions 101 and 102
2. Ga i x po 1 SE 1 E Yo AMi DATA _ Figure 1 3 AMI Data Clock 1 17 BER Bit Error Rate is the rate at which errors occur relative to the clock count If 10 errors occur in 1000 clock periods the BER is 1 0x 10 7 1 18 Binary Data Data ones and zeros are represented by a two level signal See RZ and NRZ 1 19 Bipolar Violations Violations of the coding rules in which two consecutive bits have the same polarity The data bit which violates the coding rules is normally designated V Bm fe 0 Dae fe fom Le ne On 1 P0 den 0 md I AMi DATA VIOLATION wx IFOGA LU Ln mess Figure 1 4 Bipolar Violation 1 20 Codes Refinements of the AMI code in which long sequences of zeros are eliminated by substituting a fixed pattern for the sequence of zeros The substitution allows the clock signal to be more easily recovered from the data when long runs of zeros occur The codes referred to in this manual are as foliows HDB2 83ZS High Density Binary 2 HDB2 Binary 3 zeros substitution B3ZS are two similar codes in which a pat tern is substituted for each block of three consecutive zeros in the data stream Model 3780A Fa Ton f ee On fone EA EE EE 1 11 1 1 AMi DATA I Ju 428 2 8325 DATA SUBSTITUTED PATTERN Figure 1 5 HDB2 Data HDB3 High Density Binary 3 substitution and B6ZS Binary 6 Zeros substitution are codes with substi tutions for 4 and 6 co
3. E 9 AMO e H TU nen TFT A I ZI iis AS rian HEWLETT PACKARD CE RTIFICATION Hewlett Packard Company certifies that this product met its published specifications at the time of shipment from the factory Hewlett Packard further certifies that its calibration measurements are traceable to the United States National Bureau of Standards to the extent allowed by the Bureau s calibration facility and to the calibration facilities of other International Standards Organization members This Hewlett Packard instrument product is warranted against defects in material and workmanship for a period of one year from date of shipment During the warranty period Hewlett Packard Com pany will at its option either repair or replace products which prove to be defective For warranty service or repair this product must be returned to a service facility designated by HP Buyer shall prepay shipping charges to HP and HP shall pay shipping charges to return the product to Buyer However Buyer shall pay all shipping charges duties and taxes for products returned to HP from another country HP warrants that its software and firmware designated by HP for use with an instrument will execute its programming instructions when properly installed on that instrument HP does not warrant that the operation of the instrument or software or firmware will be uninterrupted o
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5. Packaging Connectors 1 6 Protection Table 1 1 Specifications continued Open short circuit Modified hp 1700 series oscilloscope case with fan clip on front cover with space for power cable accessor ies and instruction manual Dimensions protected max 7 3 4 x 13 3 16 x 18 5 8 in voltage 5V short Weight 12 5kg 272515 net term Format One pulse per sequence Environment Operating temperature range 0 to PRBS only 55 C Position Near the start of the Storage temperature range 40 to longest zero block TOS 0 in PRBS Width Nominally one clock Accessories hp 15508A P PA C impedance RUN DEE 75 ohms unblanced to 110 ohms around balanced impedance passive conver Amplitude LV pk pk min ters having frequency range IOM Hz Transition Less than 585 Times id Notes Al transition times relate to 10 MU 90 of puise height All pulse widths Overshoot Less than 10 of pulse specified at 50 ot pulse height ampiitude I f Protection Open short circuit pro OPTIONS tected max voltage 5U bant ferm E 001 All words replaced by 16 bit front Format Detector clock avail panel programmable word This can SEI also provide two 8 bit words alter Width Nominal 50 diy nated by an externai signal applied cycle for recovered via the rear panel Changeover 5 deck synchronous with end of words Zero Impedance 50 a adde add then operates on individual 8 bit ground Wes and trigger output 15 8 bits
6. Performance Tests The Operators Checks may be performed individually or in any order The control resetting information at the Operation end of each check applies to the checks when they are per formed in the order given 3 18 Equipment Required 3 19 Details of the equipment required for the Operators Checks are given in Table 1 3 Pagel 10 A summary of this equipment is given below a Signal Generator SOMHz recommended type hp 86544 b Matching Pad 50 7553 c Three 7582 cables two of which should be of the same length and construction le they should have the same delay 3 20 The Signal Generator and matching pad are used to check the external clock input and to reduce the time taken for the BER Count and Display Checks It is poss ible to perform the BER Count and Display checks using the internal clock the measurement time however will depend on the frequency used The BER 101 check on Page 3 11 which takes 3 minutes 20 seconds at 50MHz will take more than 26 minutes at 631 2kHz 3 21 Preparation for the Operators Check 3 22 Before proceeding with the operators checks a Make a note of the option number of the instru ment as given on the rear panel b Using two 7552 cables of the same length and similar construction connect the GENERATOR CLOCK O P to the RECEIVER CLOCK I P and the GENERATOR DATA O P to the RECEIVER DATA P Open Page 4 1 so that Figure 4 1 can be used for reference wh
7. Synchronisation checks Set the OFFSET NORM EXT switch to NORM and the RECEIVER MEASUREMENT switch to BINARY ERROR 3 25 Pattern and Synchronisation Checks Instruments without options 001 or 003 perform the pro cedures given in Table 3 3 Instruments with options 001 Set all controls to the reference settings given on page 4 1 or 003 perform the procedure given in Table 3 4 Table 3 3 Pattern and Synchronisation Check Procedure Instruments without options 001 or 003 rn AAN Set the WORD PRBS switch to 15 SYNC LOSS lamp on briefly PRBS lamp ON 281 the WORD PRBS switch to 20 SYNC LOSS lamp on briefty PRBS lamp ON Set the 211 n switch to n WORD lamp ON Set the WORD PRBS switch to 15 SYNC LOSS lamp on briefly WORD lamp ON Set the WORD PRBS switch to Y PRBS lamp ON Press and hold the RUN pushbutton Release the RUN pushbutton WORD lamp ON Operation Table 3 3 Pattern and Synchronisation Check Procedure Instruments without options 001 or 003 continued Procedure Check Press and hold the RESYNC SYNC LOSS BER ON Set the WORD PRBS switch to 0000 WORD iamp ON Set the WORD PRBS switch to 1000 WORD lamp ON Set the WORD PRBS switch to 1111 AIS lamp ON To reset the controls to the reference settings as required for the Format Checks S Set the WORD PRBS switch to 9 and set the 21 1 n switch to 2 1 Table 3 4 Pattern and Synchronisation Check Procedure
8. B6ZS or B3Z2S when the CODE position of the DATA FORMAT switch 12 is selected The DATA OfP connector provides a 75 ohm un balanced data output as selected with the PAT TERN and FORMAT controls The output ampli tude of the mark in binary formats is 3V and in ternary formats t2 37V The space in both for mats 5 OV The connector has open and short circuit protection and will withstand an input of up to for short periods The DELAY DATA O P connector provides a data output of the binary formats RZ and NRZ de layed by 6 bits less than a complete sequence i e 6 bits advanced on the data at DATA O P 14 In all other respects this output is identical to the normal data output The CLOCK CLOCK switch selects normal or in verted generator clock output at the CLOCK O P connector 17 The CLOCK O P connector provides a 75 ohm un balanced generator clock output The output can be normal or inverted as selected with the CLOCK CLOCK switch 16 and the output fre quency may be either an internal or external clock source The output mark amplitude is 3V 18 Operation and the space is OV The connector has both open and short circuit protection and will withstand an input of up to 6 V for short periods The TRIGGER OfP connector provides one tran sition per word or sequence coincident with the start of the word and before the longest block of zeros of a PRBS The amplitude of the trigger output is 1 and
9. Binary data bits changed to produce an error without in creasing the sequence length The errors introduced take the form of the complement of 10 data bits in each 1000 bits I 111100 CORE ale WORD 1100 ERROR BODL Lu sail Tann Io ADDED ERRORS Figure 1 9 Error Add 1 23 NRZ Non Return to Zero data remains at the one level for the whole clock period The data level is continuous between consecutive data ones I 1 0 0 1 41 1 0 1 41 0 NRZ BINARY DATA else ee N d 07 1 07 27 0 1 21 0 NRZ BINARY DATA iea EI ELDER Figure 1 10 NRZ Data In theory NRZ data rising and trailing edges are in phase with the clock edges but the 3780A clock edges coincide with the centre of the valid NRZ data 1 24 Offset Clock Frequency Generation The generation of clock frequencies which may be varied about the normal fixed frequencies F1 F2 or F3 F1 F2 and F3 are the frequencies of the crystal oscillators in the 37804 1 25 Offset Clock Frequency Measurement The measurement of the fractional frequency difference between the normal and offset frequencies ie AF offset F normal where F normal 18 the frequency 1 F2 or 3 generated in the Pattern Generator section of the instru ment making the measurement 1 26 PRBS Pseudo Random Binary Sequence A repetitive sequence 20 1 bits long generated by an n stage shift regist
10. 1251 0086 1 60 ACCESSORIES AVAILABLE 1 61 The following accessory is available for use with the 37804 and can be purchased through your nearest HP Sales and Service Office see list at rear of manual HP Model 15508A 759 Unbalanced to 1109 Balanced Converter with a frequency range from i to 10 4112 1 62 RECOMMENDED TEST EQUIPMENT 1 63 Equipment required to maintain the model 3780A is listed in Table 1 3 Other equipment may be substituted if it meets or exceeds the critical specifications listed in the table The section of the manual in which each item of test equipment is given in the USE column where P Perfor mance tests A Adjustments and T Troubleshooting Table 1 3 Recommended Test Equipment Instrument Electronic Counter dc 50MHz Critical Specification Recommended Model hp 5327A OPO11 The time base must use a high stability crystal oscillator lt 6 x 107 P day 4 x 1071 1 sec rms short term 7 x 107 0 to 50 C Must be capable of making ratio measurements as well as frequency and period The counter must also have prescaler facilities up to 10MHz input frequencies Oscilloscope 10 1 Probe 5082 Sampling Oscilloscope lt 350ps Sensitivity 5mV cm dual trace de 75MHz Impedance 1M 2 and Dual trace de 1GHz rise time 180A 1808A 1820A 21A hp 10045 hp 180 1810 1 11 Model 3780A Table 1 3 Recommended Test Equipment conti
11. it is a 50 ohm unbalanced sig nal The output has both open and short circuit protection and wil withstand an input of up to 5 V for short periods 3 9 RECEIVER INPUT CONTROLS AND CONNECTORS Set receiver clock and data input conditions 19 20 21 22 23 The DATA I P connector is a 75 ohm unbalanced input which accepts the data input for the re ceiver The data input frequency range is IKb s to SOMb s and the input sensitivity is 0 5 V pk pk The maximum input amplitude is 5V pk pk within the limits 5V The data triggering threshold can be selected with the DATA THRESHOLD switch 21 The DATA FORMAT switch selects the approp riate binary or ternary receiver operation for in coming data at the DATA HP connector 19 In the code position a choice of HDB3 or HDB2 code options 101 and 102 B6ZS or B3ZS code is pro vided with the rear panel CODE switch 13 which is common with the generator The DATA THRESHOLD switch selects the re ceiver data triggering level Trigger level should be chosen to fall within 10 and 90 of data ampli tude Binary triggering levels of GND ground 200mV or 600mV may be selected Ternary triggering levels of 200mV or 2 600mV may be selected Note In the recovered clock mode threshold level should be set closest to 50 of maxi mum input data amplitude to allow the rising edge of the clock after a fixed delay to coincide with the centre of the data pulse The
12. rear panel of the instrument When the 3780A is used at fy 44 736Mb s with a ternary coded O P and ur rormat the shape of an isolated data O P pulse con forms to a CCITT pulse mask CCITT re commendation G703 4 An equaliser opera tional when f3 and ternary coded data is selected incorporated at the data I P port automatically compensates for interstation cable losses up to 12dB at tol fc 44 736 Mb s from a 0 909V pk source 13 55 The rear panel CODE switch selects B3ZS and 8625 code formats in the generator and receiver All other controls connectors and indicators are the same as in the standard instrument Option 102 2 54 The internal cyrstal frequencies selected with the FREQUENCY switch are as follows f 1 554kHz fa 6 312kHz f3 3 152kHz These frequencies are listed on the rear panel of the instrument 13 55 The rear panel CODE switch selects B3ZS and B6ZS code formats in the generator and receiver All other controls connectors and indica tors are the same as in the standard instru ment Option 099 1 3 The frequency OFFSET Af control and the OFFSET position of the clock selection switch are deleted Alt other controls connectors and indica tors are the same as in the standard instru ment 3 16 OPERATORS CHECK 3 17 The Operators checks allow the operator to check the main functions of the instrument prior to use A complete specification check is given in Section 1
13. use packaging storage and shipment 2 3 INITIAL INSPECTION 2 4 Inspect the shipping container for damage H the shipping container or cushioning material is damaged it should be kept until the contents of the shipment have been checked for completeness and the instrument has been checked mechanically and electrically The contents of the shipment should be as shown in Figure 1 1 and listed in Paragraph 1 59 Procedures for checking the electrical operation are given in Section 1 of this manual If the contents are incomplete if there is mechanical dam age or defect or if the instrument performance fails to meet specification notify the nearest Hewlett Packard Sales and Service Office as listed at the rear of this manual If the shipping container is damaged or the cushioning material shows signs of stress notify the carrier as well as the Hewlett Packard Office Keep the shipping mater ials for the carriers inspection The Hewlett Packard Office will arrange for repair or replacement at HP option with out waiting for a claim settlement 2 b PREPARATION FOR USE 2 6 Power Requirements 2 7 The model 3780A requires a power source of 115V ac 10 to 22 or 230V ac 10 to 18 48 to 66Hz single phase The maximum power consumption is approxi mately 110V A WARNING If the instrument is energised via an autotransformer ensure that the com mon terminal is connected to the earthed pole of the power source 2
14. word 38 The OVERFLOW flag indicates that the internal 39 error or frequency count has reached or exceeded 9 10 The lt 100 ERRORS flag indicates that less than 100 errors were counted during the last error measurement The indicator 18 inhibited during fre quency offset measurements 3 13 RECEIVER OUTPUTS 40 41 42 43 The PRINTER OUTPUT connector provides an 8421 BCD output of the measurement result and current flag signal In the BER and COUNT MAN positions of the TIMEBASE switch 32 the print command is at the termination of the measure ment and in the COUNT EXT position the print command is initiated by the printer providing a positive going TTL pulse at pin 47 of this connec tor Further details of the printer output are given on page 3 13 The RECORDER OUTPUT connectors provide a high impedance current source output suitable for connection to a chart recorder The output com prises 16 current levels with a total variation of imA into an impedance of 10K ohms max There is an eleven level indication of BER and a four level indication of count and the response time is SO0ms minimum Further details of the recorder output are given on page 3 13 The RECORDER CALIBRATION switches pro vide 1mA for FULL SCALE and OmA for ZERO calibration of a chart recorder connected to the RECORDER OUTPUT connectors 41 The RECEIVER CLOCK output provides an out put of the receiver clock signal for r
15. 0598 hp 0757 0416 hp 0757 0427 hp 0757 0442 hp 15525 hp 10501A hp 854268 Rohde Schwarz type DAF EN 18084 Adantors FHS 40901 50 amp FHD 40901 75 Greenpar type 507 4718 707 hp 5055A hp 3200A hp 10526T hp 10525T hp 10525E Recommended Model PAT PAT PA PAT PAT PAT PA PA PAT PA PA PA PAT PAT PA 24 d gt General Information Table 1 4 Recommended Adaptors for Standard Instrument wm 07 Minimum Specification Recommended Typs Adaptor BNC female Greenpar GE 500 508 5082 to GR 874 1 off Adaptor N Maie 5002 hp 1250 0082 to BNC female 5052 1 off Adaptor BNC T 7543 Greenpar GE 375531 2 otf Adaptor BNC T 5052 hp 1250 0781 2 off Adaptor Banana to BNC 10111 female Adaptor BNC Male 7543 hp 1250 1288 to BNC Male 752 75543 Load BNC 15522A 5052 Load BNC 11593A Table 1 5 Recommended Adaptors for Option 002 Instrument Note The adaptors listed here are in addition to the ones listed for the standard instru ment m Minimum Specification Recommended Type Adaptor 1 6 5 6mm male Spinner BN 88 84 75Q to BNC female 7543 3 off T Installation SECTION H INSTALLATION 2 1 INTRODUCTION 2 2 This section provides installation instructions for the Model 3780A and its accessories This section also includes information about initial inspection damage claims pre paration for
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17. 75 C It is advisable to protect the instrument from extreme temperature variation which can cause excessive condensation 2 2 2 18 Packagina 2 19 Original Packasing Containers and materials identical to those used in factory packaging are available through Hewlett Packard Offices If the instrument is being re turned to Hewlett Packard for servicing attach a tag in dicating the type of service required return address model number and full serial number Mark the containers FRAGILE to ensure careful handling In any correspond ence refer to the instrument by model number and full serial number 2 20 Other Packaging The following general instructions should be used for repacking with comercially available materials a Wrap the instrument in heavy paper or plastic If shipping to Hewlett Packard for servicing attach a tag indicating the type of service required return address model number and full serial number Use a strong shipping container eg a double walied carton of 350 pound tested material Protect the control panel with cardboard and insert a three to four inch layer of shock absorbing material between all surfaces of the instrument and the sides of the container d Seal the shipping container securely e Mark the shipping container FRAGILE to ensure careful handling In any correspondence refer to the instrument by model number and full serial number 2 21 Mating Connecto
18. 8 Line Voltage Selection CAUTION BEFORE SWITCHING ON THIS INSTRU MENT ensure that the voltage selector is set to the voltage of the power source 2 9 The location of the power input connector power line fuse and voltage selector switch are shown in Figure 2 1 Remove the power line fuse Set the voltage selector switch to 115V or 230V as appropriate Ensure that the correct fuse is fitted for the voltage selected as given in Tabie 2 1 Replace the fuse CAUTION The replacement of blown fuses should not be performed without reference to the power supply troubleshooting procedure Page 8 55 Power supply assembly damage can occur if the correct procedure is not carried out A mma A IPP KA p mettons i IN OPERADAS AN SF RCT BANKS 1 E l md e PRIRSEER CHF PUT AM e REMOVE AND CLEAN AIR RRER OETARTD FREQ MHz STAND Akt POWER INPUT LINE FUSE CONNECTOR VOLTAGE SELECTOR SWITCH Figure 2 1 Power Input Fuse and Voltage Selector 2 10 Fuses 2 11 The power line fuse depends on the supply voltage selected Table 2 1 provides the ratings and Hewlett Packard stock numbers of suitable fuses Table 2 1 Fuse Ratings Voltage Selector HP Stock Number 2110 0381 2110 0304 115V 3A Timed 250V 230V 1 54 Timed 250V 2 12 Power Cable 2 13 In accordance with international safety standards this
19. Amplitude 1 pk pk min l EE is ge Ras External input 250mV pk pk Times sensitivity squarewave DC to Overshoot Less than 10 of SCH Ge ES pulse amplitude S GE Sie 5 Protection Open short circuit a d qM protected max vol I Mn i tage SV short term qee SE uns Impedance nominally 1000 10 10 ohms i15V ot 230V 22 18 002 Siemens 1 6mm connectors replace AC 48 66Hz max all external 75 ohmsBNC connectors consumption approx 110 003 Combination of options 001 and 002 External fused supplies of nominally 099 Clock frequency oifset generation 5V 200mA and 5V 200mA for deleted HP logic probes rear panel 100 Internal clock frequencies of 2048 8448 and 34368kHz When the 3780A is used at 3 34 368 Mb s with a ternary coded output amp in put format the following parameters apply All signal connectors are BNC except Data Output impedance Nominal 754210 ground options 002 003 Amplitude 1 to LV Printer output via 50 pin Amphenol Yero Level ov to 1V connector Transition lt 4ns Recorder output via two binding Times posts Overshoot lt 10 pulse Amplitude 195 x 335 x 475mm H x W x L Data Input Rate Nominal 34 368Mb fs Impedance Nominal 754216 ground Equalisation Automatic Yf equalisa tion for cable losses up to 1218 at fcf from a 1V pk source Format Ternary coded HDB2 or HDB3 Amplitude 3V pk max Indicator LED iHuminated if data transitions pres
20. CAB or violations of violations VIOLS with internal switch A3481 H 13 For Binary Errors ensure that synchronism has been achieved by observation of the RECEIVED PAT TERN indicators 14 Select TIMEBASE and DISPLAY MODE BER over 10 108 or 107 clock periods or COUNT MAN UAL or EXTERNAL Note In BER the measurement starts automa fically in COUNT MANUAL the measure ment is initiated with the START switch and in COUNT EXTERNAL the measure ment is initiated from an external printer 15 Ensure that the receiver is operating correctly by observing the GATING indicator 3 35 FREQUENCY OFFSET MEASUREMENT 3 36 To set a required generator offset proceed as follows i Select the generator FREQUENCY d f Or EI 2 Select the OFFSET position of the generator CLOCK SELECTION switch 3 Set the receiver MEASUREMENT to FREQUENCY OFFSET 4 Ensure correct operation by observing the display and GATING indicator 5 Adjust the generator OFFSET control to give a dis play of the required offset 3 37 To measure the offset of an external data input pro ceed as follows i Connect the external data input to the receiver DATA HP connector 2 Select the RECOVERED position of the receiver CLOCK format switch 3 Connect the receiver CLOCK output on the rear panel to the generator CLOCK I P 4 Set the generator CLOCK SELECTION to EXT 5 Select the comparison frequency with the generator FREQUENCY swi
21. DATA INPUT TRIGGER indicator lamp is on when data applied to the DATA I P connec tor 19 is correctly triggered The lamp will be off if data transitions are absent for more than 150mS The CLOCK switch selects the receiver clock source In the EXT and EXT positions the receiver is clocked with a normal or inverted input applied to the RECEIVER CLOCK HP connector 24 In Model 3780A the RECOVERED position the receiver is clocked with a signal recovered from the data at the DATA MP connector 19 The appropriate clock re covery frequency is selected with the FRE QUENCY switch 2 24 The CLOCK UP connector is an unbalanced 75 ohm input for a receiver external clock in the fre quency range 1kHz to 50MHz The input sensi tivity is 0 5V pk pk and the maximum input am plitude is 5 pk pk within the limits 35V The clock triggering threshold can either be ground or automatic mean level of clock input as selected with the CLOCK THRESHOLD switch 5 The CLOCK THRESHOLD switch is common with the generator 25 The RECEIVER CLOCK INPUT TRIGGER indi cator lamp is on when a clock signal applied to the CLOCK I P connector 24 is correctly triggered The lamp will be off if clock transi tions are absent for 150 ms 3 10 SYNC AND SYNC INDICATORS Automatic synchronisation with manual override and re ceived pattern indication 26 The RESYNC switch is a manual override on the automa
22. F 3 for clock loss F 4 for data loss fo A for AJS BER print command given on termination of measurement COUNT MAN print command given on STOP command from front panel COUNT EXT print command given on STOP command from printer Recorder Output rear panel Error Output rear panel Print Command Format impedance Range BER LEVELS PSD 1 1 1 1 i i LEVELS REFERENCE FSD 15 Signal no errors except 7 Signal 51954 AIS errors 4 Syne loss 2 ATS 0 Signal Loss Note when using recovered clock signal loss data loss when using external clock signal loss clock loss 5 4 3 2 i 0 9 O gt Ch I Calibration Format impedance Amplitude Transition Times Overshoot General information TTL pulse min print cycle time 500 ms Current source with S00ms minimum response Greater than 50K ohms imA variation over 16 levels into 10K ohms max Thirteen level signal BER S16 109 Sync Loss AIS Signal Loss Five level signal Two rear panel push buttons giving FSD and Zero Internal ad justment of range mA t 0 2mA and centering OMA to 0 5mA One pulse per error inhibited during sync loss 50 ohms nominal to ground IV pk pk min Less than 5 5 Less than 10 of pulse amplitude 1 5 Model 3780A Trigger Output rear panel Clock Output rear panel GENERAL Power Supply Probe Power
23. GENERATOR DELAYED DATA O P to the RECEIVER DATA UP To reset the controls as required for the COUNT BER and Display Checks Disconnect the cable from the GENERATOR DELAYED DATA O P and connect the GENERATOR DATA O P to the RECEIVER DATA I P Set the WORD PRBS switch to 1000 options 001 and 003 to 16 with the WORD SELECT switches at 10000000 00000000 3 27 Count BER and Display Checks Set ali controls to the reference settings given on Page 4 1 with the following exceptions Set the WORD PRBS switch to 1600 options 001 and 003 to 16 with the WORD SELECT switches at 1000 0600 0000 0000 Set the ZERO ADD NORM ERROR ADD switch to ZERO ADD Set the ZERO switch to 996 options 001 and 003 to 984 Set the RECEIVER INPUT FORMAT switch to AMI Set the RECEIVER MEASUREMENT switch to CODE ERROR Perform the procedure given in Table 3 6 Table 3 6 Count BER and Display Check Procedure Procedure A Set the RECEIVER BER COUNT Switch to COUNT MAN Press the STOP pushbutton Set the WORD PRBS switch to 1111 options 001 and 003 to 16 with aii WORD SELECT switches at 1 Set the ZERO ADD NORM ERROR ADD switch to NORM Set the OFFSET NORM EXT switch to EXT With the generator receiver clock and data cables still connected connect the 8654A Signal Generator set to 5OMHz to the GENERATOR CLOCK Up via a 50 7542 matching pad if a Signal Generator ts not available see paragraph 3 20 Set the Siana
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25. Instruments with options 001 or 003 Set the PRBS WORD switch to 20 SYNC LOSS lamp on briefly PRBS lamp ON Set the PRBS WORD switch to 15 SYNC LOSS lamp on briefly PRBS lamp ON Set the PRBS WORD switch 16 9 SYNC LOSS lamp on briefly PRBS lamp ON Press and hold the RESYNC pushbutton SYNC LOSS lamp ON Release the RESYNC pushbutton PRBS lamp ON Set the PRBSAVORD switch to 16 WORD lamp ON Set the WORD SELECT switches as follows 10000000 WORD lamp ON B 00000000 Set the WORD SELECT switches as follows A 11141119 WORD lamp on at each stage of B 11111110 switching Set the WORD SELECT switches as follows A 111114 AIS iamp ON 3B 141114111 To reset the controls to the reference settings as required for the Format Checks Set the PRBS WORD switch to 9 and set all WORD SELECT switches to 0 3 26 Format Checks Set all controls up to the reference settings given on page 4 1 and perform procedures given in Table 3 5 3 9 Model 3780A Table 3 5 Format Check Procedure JR Set the ZERO ADD NORM ERROR ADD DISPLAY 1 0x 107 Switch to ERROR ADD Set the CLOCK CLOCK switch to CLOCK ONES ZEROS lamp ON Set the RECEIVER CLOCK switch to EXT PRBS lamp ON Reset the CLOCK CLOCK switch to CLOCK Disconnect the cable between the GENERA TOR CLOCK O P and the RECEIVER CLOCK Up x Set the RECEIVER CLOCK switch to RE COVERED J Add an extra 4 Z it 1 2012 0 15m to the cable from
26. LAN T IIA GER ENG ii 5 SE EE V AO ORES ER ARTEN EE EE EE bet 2722592342 Figure 1 1 The 3780A Pattern Generator Error Detector PEASE OSES ESS 2 2 MI Az AN SIT Sod S ES FER Y tz d f i EREET RE APON f d SAAS Eas IO HE fi RER EO A EE EUH YT 1 5 d Br Saree 1 0 General Information SECTION 1 GENERAL INFORMATION 1 1 INTRODUCTION 1 2 This Service Manual contains the information necessary to install operate and maintain the Hewlett Packard Model 3780A Pattern Generator Error Detector The instrument and accessories supplied are shown in Figure 1 1 1 3 This manual is available in 6 x 4 inch Microfiche each containing up to 95 photo duplicates of manual pages The Microfiche package includes the latest Manual Change Supplement and all pertinent Service Notes The part numbers of this manual in microfiche form as given on the title page should be quoted when ordering 1 4 An Operating Manual is also supplied with this in strument and should be kept with the instrument for use by the operator 1 5 SPECIFICATIONS 1 6 The specifications of this instrument are listed in Table 1 1 These specifications are the standards against which the performance of the instrumen
27. NUAL in section I Copyright HEWLETT PACKARD LIMITED 1981 SOUTH QUEENSFERRY WEST LOTHIAN SCOTLAND MANUAL PART NUMBER 03780 90023 Microfiche Part Number 03780 90048 Printed March 1981 Model 37804 H a wey See E MC MXN warn 3 et D x 4 S amp re 22 H N 2 x Ge po i x e 3 Et E 2 2 x E 5 e ET i a s H LE OPERE Wt fd CLR TTE ALDEA EAS SARS ESOS ERLE g E AS AALAY A H H IMITATA EE VIDETE it ee RER B Z44128 FR UY HANDS 3 ott 212412 ETIAM H I IL PIE PNIS I IVA Er IES ISTIS j 11227 4227 i uiu e 5 EFE fite E ZE E TEE d EE ay E SE 2 ZE EE EE SHAH SSAA RSP Y PERS ESTAS ese E sites YQ SN OH d ARI AORTA A BESSERE ERLERNTE Sa AQ eee Tare AT AN RR PA AT VIE TU EET EE NAA MI
28. OPERATING AND SERV ANUAL si E uo PU t tt by TREE Gee qae CE Ta E vtl t wh BRR SU Ser ee Ann Berg x i We SE i k gt Nd A RA ie g decias GE rk H gt M d aa i 8 H H 1 i D tm H im ILLO j H E ra K H n Se AN HE STIP P eur nne E r r d id k un i PEA x i s 3 Y E 3E i o DE i kg KW ta paseoa j 3 lesu niso TER A nt Das v ani ir Ad H i j i Fee KW E JEE ei mimi ASIA 3 En l er es QUAE rines P og H 2M AS 5 A 2 T DH e Ls d 5 dA MR 1 H N ER A 5 m d TEN H SS 4 4 d P ZS AE i 2 2 stat BARS GS 1 SEE eet UNI si Se Ss Rivales ont Oqe E 2 i ek TED e Es x fe H aa E Pier rn ES 3 Q Q Q D G er seu ihe Bele ue ae SE JW pvt 3 irse EA Sal T ESAS warn Q DURS i 1 z o1 E t iS titik i 1 y A bf imeem emo gent coon Ewen PESE 2 08 i ES Nos E E n aeter te ui S AP Mikai qasasqa a did Aic aa o Visi nmn inm A d Ju QUA a dy ci m xm Mate REIR jm
29. OUNT CONTROL FROM PRINTER P PRINT COMMAND FROM 3780A TO PRINTER Figure 3 2 Printer Output Socket as Viewed on Rear Panel 3 13 Model 3780A The flag signal information is coded as follows PRINT OUT FLAG 1 OVERFLOW 2 SYNC LOSS 3 CLOCK LOSS 4 DATA LOSS V LESS THAN 100 ERRORS AIS Note On standard Hewlett Packard 50554 and 5050B printers V is produced for decimal 15 or binary 1101 print commands 3 44 The print command in the BER mode of operation is given at the termination of each measurement The print command in COUNT MANUAL is given when the STOP switch is pressed and in COUNT EXTERNAL on receipt of a stop command from the printer The print command isa 1 1 1 pulse and the minimum print cycle time is 500ms 3 45 RECORDER 3 46 The recorder output provides a high impedance current source output suitable for connection to a chart recorder The output comprises 16 current levels with a total variation of imA into an impedance of 10K ohms max Two pushbutton switches give Full scale and Zero outputs for setting up the recorder and there are internal adjustments for range ImA t 0 2mA and centre O to O 5mA The minimum response time is 500ms The out put levels are as follows Level 15 PSD BER Thirteen level signal LEVELS BER FSD 15 10 14 1977 i3 10 12 lt 110 7 1 107 10 10 9 cq 8 D SE eI 6 10 4 Sync loss 2 AIS 0 Signal loss 3 14 COUNT Five level signal LE
30. TA HP 19 for violations of the coding laws The coding law is selected with the receiver DATA FORMAT switch 20 as either AMI or CODE and in the CODE position the type of code HDB3 82 option 101 and 102 5628 B3ZS is selected with the rear panel CODE switch 133 which is common with the generator The resuit may either be displayed as a bit error rate or error coun as selected with the TIME BASE switch 52 The measurement range is 0 0 x 10 to 9 9 x 107 in BER 10 00 x 10 to 9 9 x 10 in COUNT As an alternative to violations of the coding laws it is possible with HDB2 HDB3 to measure viola tions of violations where an error is registered for each violation which has the same polarity as the previous volation An internal switch 3451 selects between measurements of the coding law errors VOCAB and measurements of violations of violations VIOLS in the BINARY ERRORS position the receiver measures the binary errors on a binary or a coded input applied to the DATA I P connector 19 The binary errors are measured on a bit by bit basis using a reference pattern generated in the re ceiver The result may either be displayed as a bit error rate or error count as selected with the TIMEBASE switch 32 The measurement range is 0 0 x 107 to 4 0 x 107 in BER and 0 0 x 10 to 9 9 x 10 in COUNT H the test signal being received is one of the fixed 4 bit words or with options 001 or 003 8 16 bit word two meth
31. VELS REFERENCE FSD 15 Signal no errors except 7 Signal plus errors AIS 4 Sync loss 2 AIS 0 Signal loss Signal loss indicates clock loss when using an external clock and data loss when using recovered clock 3 47 COUNTER 3 48 To make large error counts with greater resolution than is possible on the 3780A display an external counter may be connected to the rear panel ERROR output socket The output is one pulse per error the pulse amplitude being IN pk pk minimum The output is inhibited during sync loss 3 49 OPERATORS MAINTENANCE 3 50 The only routine maintenance which should be per formed by the operator is the cleaning of the air filter as described in Paragraph 3 51 CAUTION The replacement of blown fuses should not be performed without reference to the power supply troubleshooting procedure Page 8 55 Power supply assembly damage can result if the correct procedure is hot carried out 3 51 Air Filter Cleaning 3 52 The instrument has an air intake f ter which is fixed to the rear panel with four screws This fiiter should be re moved and cleaned at intervals of approximately one month depending on environment Wash the filter mesh in clean soapy water rinse thoroughly and dry before re fitting WARNING The instrument should not be operated with the air filter removed and the fan blades exposed
32. d Display Control of error counter timebase may be internal over 10 10 or 10 clock periods manual via start stop push buttons or exter nal via the printer output connector Internal error counts are displayed as a scaled BER reading in the form X Y x 10 Error counts over a manually or externally con trolled timebase are displayed as a scaled COUNT reading in the form X Y x 10 Frequency offset is displayed as a fraction of the nominal centre frequency in the form XY x 107 where n 6 usually The display uses seven segment LED characters 1 47 Fiags Indications of measurement gating sync loss and count overflow are provided by LED lamps An indi cation is also given if the last measurement result is based on less than 100 errors 1 48 Self Check Error Add A fixed binary error rate of 10 may be injected into the test pattern in order to check the error detector functions ERROR ADD and ZERO ADD cannot be used simultaneously 1 49 Trigger Outputs trigger output giving one transi tion per sequence is available from a front panel socket on the generator The output is modified during zero add to allow examination of the zero block or the pattern immediately following it on an oscilloscope 1 50 The receiver section also provides a trigger output for PRBS only giving one pulse per sequence from a rear panel socket 1 51 Error Detector Outputs In addition to receiver trigger and clock outputs there are th
33. d that periodic requests for the latest Manual Change supplement are made to one of the Sales and Service offices listed at the rear of this manual 1 13 For information concerning a serial number prefix which is not listed on the title page or in the Manual Change supplement contact the nearest Hewlett Packard office 1 1 Model 3780 Table 1 1 Specifications Notes 47 transition times relate to 10 to 90 of pulse height All pulse widths specified at 50 of pulse height PATTERN GENERATOR 2 Internal Clock Clock Offset External Clock Clock Output Frequency Accuracy Stability Format Jitter Range Frequency impedance Triggering Sensitivity Amplitude Indicator Polarity Impedance Amplitude DC Offset Transition Times Overshoot Protection Patterns Three crystal clocks 1536 2048 and 448k Hz Better than 3ppm at ambient Typically better than 12ppm 0 C to 55 C Typically better than t Sppm year ageing Square wave 50 2 6 duty cycle Less than 0 595 of period 1 50 ps pk pk Continuously variable up to at least S0ppm about installed crystal frequencies offset can be displayed in receiver Data Format 16112 50 4 2 75 ohms nominal to ground Automatic or ground threshoid switch min pulse width 30 of period 2 ns Better than 500mV pk pk SV pk pk max limits 5V LED illuminated if ciock
34. e OV 0 3V mark 3V 0 3 Other specifications as for main data output Clock Data NRZ Data Phasing RZ Data Format Trigger Output Position Width impedance Amplitude Transition Times Overshoot Protection ERROR DETECTOR Data Input Rate Impedance Triggering Sensitivity Amplitude Indicator Rising edge of clock nominally in middle of data Clock and data nomi nally coincide Clock Recovery Square wave with one transition per word or sequence Transitions nominally coincident with start of word or before first zero of longest zero block in PRBS Equal to word or se quence length but output held at zero during zero add 50 ohms nominal to ground 1V pk pk min Less than ns External Clock Less than 10 of pulse amplitude Open short circuit protected max vol tage 5V short term 1Kb s 50Mb s 75 ohms nominal to ground Choice of nominal threshold 200mV 600mV or ground min pulse width 30 of period 2ns Better than 500mV pk pk SV pk pk max limits 5 LED illuminated if data transitions pre Clock Data Phasing sent Binary Ternary Codes Frequency Mode Frequency Polarity Impedance Triggering Sensitivity Amplitude Indicator Recovered Clock External Clock General Information NRZ or RZ RZ AMI or coded HDB3 or HDB2 rear panel switch common with
35. ecovered or ext clock The output amplitude is 1V min pk pk and the pulse width is nominally the same as the clock with a 50 duty cycle for recovered clock The connector has both open and short circuit protection and will withstand an input of up to 25 for short periods The output impedance is 50 ohms 3 5 Model 3780A 44 45 The ERROR output connector provides one pulse per error The output pulse amplitude is IV min pk pk and the pulse width is nominally the same as the clock mark The connector has both open and short circuit protection and will withstand an input of up to 5 V for short periods The impedance of this output is 50 ohms and the output is inhibited during sync loss The RECEIVER TRIGGER output provides one pulse per received PRBS sequence near the start of the longest zero block The output pulse am plitude is 1V min pk pk and the pulse width is nominally one clock period The connector has both open and short circuit protection and will withstand an input of up to 5V for short periods The output impedance is 50 ohms 3 14 POWER CONTROLS AND CONNECTORS 46 The POWER INPUT module comprises a supply voltage selection switch the supply fuse and a socket for the power supply cable Details of set ting the supply voltage switch and fuse selection are given on page 2 1 Paragraph 2 8 WARNING Before connecting the instrument to the supply ensure that the voltage selector is in the correct
36. ent 101 Internal clock frequencies of 1544 6312 and 44736kHz HDB3 HDB2 codec replaced by B6ZS B3ZS codec When the 3780A is used at f3 44 736 Mb s with a ternary coded O P amp 1 P for mat the following parameters apply Data Output Impedance Nominally 7552 unbal anced Shape Conforms with CCITT pulse mask for co axial pair interface at 44 736 Mb s CCITT recom mendation G703 4 Amplitude Nominally 0 6V pk Data Input Rate Nominally 44 736Mb fs Impedance Nominally 7 5452 unbal anced Equalisation Automatic Jf equalisa tion for cable losses up to 1245 at fc 5 froma 0 909V pk source Format Ternary coded B6ZS or B3ZS Amplitude 3V pk max Indicator LED iliuminated if data transmission present 102 nternal clock frequencies of 1544 6312 and 3152kHz HDB3 HDB2 codec replaced by B6ZS B3ZS codec 1 14 DEFINITION OF TERMS 1 15 The following are brief definitions of terms which relate to the functions of the instrument and are common y used in this manual 1 16 AMI Alternate Mark Inversion is a form of Ternary data des cribed below in which data Marks normally represen ting ones are alternately positive and negative going The advantages of this basic code are that the average dc potential on the line is zero and that this code can be used to detect if one data bit is missing as two consecutive bits would then have the same polarity General Information p
37. er For example a 9 stage shift register produces a sequence 252 or 511 bits long 1 27 Recovered Clock The receiver clock signal recovered from data 1 28 RZ Return to Zero data is at the One level for the duration of the clock mark and returns to zero for the duration of the clock space a al a uu pee y BINARY DATA Figure 1 41 RZ Data 1 29 Synchronisation As used in the 3780A synchronisation is the generation in the Error Detector of the particular sequence being re ceived The sequence generated in the Error Detector must be in phase with the received sequence for correct synchronisation General Information 1 30 Ternary Data One and Zero are represented by a three level signal Ternary data is a general term which includes AMI and the codes described in this section 1 31 Word A repetitive fixed sequence 1 32 Zero Add Zeros added to each sequence which increase the sequence length 1110 011 1 00 WORD 100 ZERO ADD 002 Figure 1 12 Zero Add 0 1 33 DESCRIPTION 1 34 The 37804 Pattern Generator Error Detector is a complete error measuring system contained in one portable unit The instrument measures Binary and Code errors on digital transmission equipment operating at bit rates in the range 1Kb s SOMb s Frequency Offset measurements can also be performed at the frequencies installed in the generator 1 35 Binary Error
38. g SI Surr 88r ou Good OLAV 943 Ul pc pue p 10129uuo2 d I YOOTO Sy Pla JUSUIRISUT y JO Suorjoos ioAIooOY pu 36 38 3 2 ujOq 03 pardde SIpu3is yoo geuriejxo JOJ ploysely SuLrm32i 59 sjoopes YOUMS Q IOHSTHHI 013 sl suyo JO 939 8569 ue uyta Indur poour equn ue st 31 1 YIHMS NOJLOATAS 320710 943 Jo 866569 LX3 y JO uono r s Aq pojqguo st ndu SYL AS X Sam oy wyp yd yd AS St Spayfdue unwixew 99 pue yd yd AS 0 St AxrAnisues md 23 ZHWOS oi ZHA 98 5 593 ur OJRIOUEs oui 10 ndur Yoo euiejxo ug 519323 rojoouuoo d l MOOTO ML 809569 185440 SU ut St 1 YOUMS NOLLOATAS MOOTO 5 5 AH 212do most 0 805 styg 9005 y o1 dn Aq yopms AQNANOAA 9 UM 991525 Ey ro Cy Tj 89 pexij 5 tro Aouonboii 89 5015 101e1ou92 oy AIBA 03 p sn oq UBD o1ijuoo GV LHSddO UL ZO L vondo LoL uondo 001 vondo DIEPUEIS 5919 9 5944 5 059 0 L Sigel EE QEL ui USAIS SIE 2 531393 23 au Fuswmmsur syz JO ougd Jeol oui uo pags ore 5 pue Uy Aq pozeorpur sapuenb 91j 991 peloe ss si EZ 53 5 YOOT 19A199 21 94 JO uontisod 8 5 Daun I A199 31 eu ut 3 83 3 lsaodal Yolo 9151 140 608 ou 5159 58 ose YOUMS snp uongoss ioljgjou d oui IO 831808 MOO SE 53018 50 5 5 35 PUIOjUI dary JO euo s s yms AINANOJAI ML 10319032 J
39. generator At the three internal rates of generator selection switch com mon with generator Operates on any data input provided there are two or more tran sitions every 20 bits data loss inhibits clock recovery cir cuit 182 50MHz CLOCK or CLOCK switch 75 ohms nominal to ground Automatic or ground threshold switch com mon with generator min pulse width 30 of period 2ns Better than 500mV pk pk SV pk pk max limits L5V LED illuminated if clock transitions pre sent Automatic phasing Rising edge of clock should be nominally in middle of data pulse typically 3ns internal delay of clock relative to data bet ween inputs and sam pling point 1 3 Model 3780 Synchronisation Measurements WORD Indicators Mode Syne Loss Manual Resync Time Modes BINARY ERRORS CODE ERRORS AMI HDB3 HDB3 HDB2 HDB2 B3ZS B6ZS Table 1 1 Specifications continued by generator exclud ing added zeros and alternating words re BER mmm LED indication of pat torn ock for PRBS PRS WORD and AIS Gndicators inhibited during syne loss and code error or tre quency offset meas urements Automalic with man ual override Greater than approx 20 000 errors in 500 000 clock periods Sync override via push button forcing a sync loss Typically Jess than 500 bits Binary errors code errors frequency off set Closed io
40. he maximum vol tage is 15 V rms 51 The WORD SELECT switches select the content of the 16 bit or two 8 bit words produced by the generator 10 52 The ZERO ADD NORM ERROR ADD switch performs the same function as in the standard instrument as described on page 3 2 Zeros are added once per sequence to the 16 bit word between words or indivi dually to the 8 bit words 18 53 The TRIGGER output socket provides a trigger output of one transition per word or sequence as for the standard instrument des cribed on page 3 3 With the 16 bit word the transition occurs before each word and in the alternate mode the transition occurs before each 8 bit word A or B All other controls connectors and indica tors are the same as the standard instru ment Option 002 Option 002 instruments have small Siemens connectors in place of the 75 ohm BNC connectors All other controls connectors and indicators are the same as in the standard instrument Option 100 2 54 The internal crystal frequencies selected with the FREQUENCY switch are as follows d 2 048kHz f 8 448kHz 34 368kHz These frequencies are listed on the rear panel of the instrument All other controls connectors and indicators are the same 88 in the standard instrument Option 101 2 54 The internal crystal frequencies selected with the FREQUENCY switch are as foliows fi 1 554kHz f 6 31 28882 fa 44 736kHz These frequencies are listed on the
41. ile performing the Operators Checks Note In some of the following checks the instrument will loose synchronisation during the setting up pro cedure and the SYNC LOSS lamp will come on Unless otherwise stated the check relates to the condition after synchronisation has been regained 3 23 CHECK PROCEDURES 3 24 Frequency and Offset Checks Set all controls to the reference settings given on Page 4 1 and perform the procedure given in Table 3 2 3 7 Model 3780A Table 3 2 Frequency and Offset Check Procedure NEN ONE NNI N Switch the POWER ON RECEIVER CLOCK i P lamp on RECEIVER DATA I P lamp on PRBS lamp on lt 100 ERRORS lamp on DISPLAY 0 0 x 107 GATING lamp FLASHING Set the f 1 f2 f3 switch to 2 GATING lamp FLASHING Set the F 1 12 f3 switch to 13 GATING lamp FLASHING Set the OF FSET NORM EXT switch The displayed offset increases from to OFFSET 0 0 x 10 when the OFFSET Set the RECEIVER MEASUREMENT Af control is varied in either switch to FREQ OFFSET Af f direction from its mid position Set the 11 12 13 switch to 2 The displayed offset increases from 0 0 x 107 when the OFF SET Af control is varied in either direction from its mid position Set the f 1 12 13 switch to f1 The displayed offset increases from 0 0 x 107 when the OFFSET Af control is varied in either direc tion from its mid position To reset the controls to the reference settings as required for the Pattern and
42. instrument is equipped with a three wire power cable When connected to an appropriate power receptacle this cable grounds the instrument cabinet The type of power cable shipped with each instrument depends on the country of destination Figure 2 2 illustrates the standard power receptacles that are commonly used The HP stock number 2 1 Model 3780A 8120 0696 CABLE STOCK NUMBER 8120 2104 8120 1692 8120 1703 8120 1521 Figure 2 2 Power Receptacles shown with each receptacle is the stock number of a power cable equipped with the appropriate mating plug for that receptacie If the appropriate power cable is not included with the instrument notify the nearest hp Sales and Service Office and a replacement will be provided 2 14 The colour codes used in each power cable are Table 2 2 Power Cable Colour Codes Brown Blue Green Yellow Line Neutral Ground WARNING BEFORE SWITCHING ON THIS IN STRUMENT the protective earth ter minal of this instrument must be connec ted to the protective conductor of the mains power cable The mains plug shall only be inserted in a socket outlet provided with a protective earth con tact The protective action must not be negated by the use of an extension power cable without a protective con ductor grounding 2 15 STORAGE AND SHIPMENT 2 16 Temperature Range 3 17 The instrument may be stored or shipped in temper atures within the limits 40 C to
43. ion fre quency over 10 clock periods of internal standard crystal rate Automatic XY x 107 with auto matic round up Up to 25kHz deviation from nominal crystal rate 1 count relative to the internal standard clocks Display strobed at end of gating interval maximum refresh ment rate 2Hz Display continuously updated with round up when measure ment ends Flags 1 51 s Printer Output rear panel Gating Sync Lass Overflow lt 100 Errors Format Flags Print Modes Table 1 1 Specifications continued indicates mleasure ment in progress will extinguish for al least between rags tie PAC THES Indwwares local pat tern reference has lost syne display blanks and measurement 15 terminated BER or halted COUNT flag remains Ut for at least S 0ms BER ot held COUNT until measurement is ter minated Sync loss inhibited during code error and frequency offset measurements Indicates internal error or frequency count 210 display blanks and measurement is terminated BER or halted COUNT flag remains Ht for at least 500ms BER or held COUNT until measurement is ter minated indicates less than 100 errors counted during last error measure ment inhibited dur ing frequency offset measurements 8421 BCD 10 columns BER F X Y 10 N COUNT F227 y tu 10 N V for lt 100 errors F for overflow F 2 for syne loss
44. l Generator to produce a A00mV peak to peak signal at the GEN ERATOR CLOCK UP Press the START pushbutton Check Display counting up The count is held and displayed GENERATOR CLOCK Up lamp ON The count increases to 9 9 x 10 The display blanks with the GATING lamp OFF and the OVERFLOW lamp ON NOTE measurement time 20 seconds Continued on Page 3 12 Model 3780A Table 3 6 Count BER and Display Check Procedure continued Set the RECEIVER BER COUNT switch to BER 109 to BER 10 to BER 10 Switch to ZERO ADD Set the ZEROS switch to 037 options 001 and 003 to 025 with the WORD SELECT switches at 11110000 0000 0000 Press the START pushbutton 3 28 OPERATING PROCEDURE 3 29 INTRODUCTION 3 30 The 3780A PATTERN GENERATOR ERROR DE TECTOR measures binary errors code errors and fre quency offset The measurements may be local using a loop back method or through a channel under test to a remote error detector 3 31 BINARY OR CODE ERROR MEASURE MENTS 3 32 To make Binary Error or Code Error measurements proceed as follows 3 33 Generator 1 Select the generator FREQUENCY either internal NORM f f5 fa or external EXT from the CLOCK HP Select the generator pattern 2 n_ PRBS bit word or one of the fixed words Select the generator output format RZ or NRZ for binary outputs AMI or CODE including rear panel CODE format for code outputs Connec
45. nsecutive Zeros respectively i i 0 11 1 0 Le Bebe of 1 1 1 1 AMI DATA a SUBSTITUTEO HDB3 DATA PATTERN Figure 1 6 HDB3 Data fame Deia r Ban pe 1 0 0 9 AM DATA 8675 DATA SUBSTITUTED A e 229905 Figure 1 7 8625 Data 1 20 Violation of Violation HDB2 HDB3 only eb mp 0 a E E Qmm pes eres EE i 6 l Da H f ME h ps pop U D eee f n 7 n BOB i bf c ME HOP ob TCR 1 r TEES RUN ONE T RUE tf Y al Ped Fil AS PR VIOOS VIOLATION O82 L P oe azu Sr ee a a FTSE is Tvi ZC 0 7 wx Ui ii EJ YRDLATIGN 15 SAME AS PREVIOS VIDLATHDIN o La X nH Figure 1 8 AMI Data 1 8 Instruments fitted with 51 on the 03780 601 34 Board have an additional mode of operation In the VOCAB position a code error 15 recorded when a violation two successive bits of the same polarity of the coding rule occurs In the VIOLS position a code error is only recorded when there are two successive violations of the same polarity With AMI code errors any violation ofthe AMI coding rule is recorded as code error irrespective of the position of the VOCAB VIOLS switch 1 21 Delay Data As applied to this instrument delay data is data which is delayed by 6 bits less than a full sequence ie it is 6 bits in advance ofthe normal data 1 22 Error Add
46. nued HF Probe 10 1 Divider BNC Adaptor VHP Oscillator Test Oscillator Function Generator Pulse Generator Digital Valtmeter Attenuator Oty 1 Attenuator Oty 2 Power Supply Resistor Resistor Resistor Resistor Cables STD Cables STD 75 5082 Matching Pad Digital Recorder VHF Oscillator Logic Puiser TTL Logic Probe ECL Logic Probe Critical Specification da 500MHz 1M input impedance TOMH 5OMEHz 0 10dBm into 5053 with a variable output contri HHz 10MHz 500mV pk pk into 7542 or greater 0 0001Hz 1MHz sine and square wave with E EV de offset control Rise times less than 2ns Min period iess than 20ns Min pulse width less than Bes Must be able to be exter nally triggered Must have compie ment output control Must give 1 6V pk pk into 5092 1mV Resolution and isolated input terminals de 50MHz O 25d8 presettable 7543 5052 20dB coaxial fixed rise time 2 5nS 0 15V 0 75A dual de power supply 3 off 7592 1 1 8W 1 off 51112 196 1 8W 1 off 1 5K 2 196 1 8W 1053 196 1 8W 4 oft 75843 BNC 2 off 5042 BNC tot 3 off de 200MHz Note When using 86914 20dB coaxial attenuator 502 Vo rien 10241 1250 0052 hp 8654 hp 6518 Option 02 hp 3310A np 8008A hp 34740A 34 702A hp 3780 hp 86915 hp 6205B hp 0757
47. ods of operation are available de pending on the setting of the PRBS WORD switch 7 With the PRBS WORD switch set to 9 15 or 20 the receiving instrument will synchronise to the incoming pattern irrespective of systematic errors With the PRBS WORD switch set to the relevant word the error detector will only synch ronise to that word The TIMEBASE switch selects the counter time base interval over which errors are counted The BER positions give a choice of 10 10 or 10 clock periods for measurement gating The 33 34 measurement result is automatically scaled and presented in the form X Y x 10 with an indi cation if this result is computed from less than 100 errors 39 In the COUNT position errors are counted over a period either selected manually with the START and STOP switches 33 and 34 or externally by a command from an external printer In this mode a positive going TTL pulse at pin 47 of the PRINTER OUTPUT connector 40 stops the counter and produces a print command The counter normally restarts 400ms after the stop command however it is possible with the change of an internal link to hold the restart until the pulse at PRINTER OUTPUT pin 47 goes negative The START switch controls the start of the manual measurement gating period when the TIMEBASE switch 32 is in the COUNT MAN position The count is initiated by the switch being depressed This switch can also be used to restart a meas
48. op bit by bit detection on any pat tern produced by generator excluding added zeros and alter nating words Violations of coding rule detected on any pattern according to the following rules where 0 space 1 mark V bipolar violation Bipolar violations are code errors 01V 10V 1 IV 0000 and 0100V are code errors Violations of violations selectabie with an inter nal switch IV 006 and 010V are code errors OVO 1VO IVI 00VI and 000000 are code errors see options 000000V and 000000 V0 are counted as single errors Display COUNT STROBING FREQUENCY Measurement of frac OFFSET tional offset of gener ator clock output from FREQ OFFSET Method Gating Format Range Accuracy Method Gating Format Range Method Gating Format Range Accuracy BER amp FREQ OFFSET COUNT Totalises errors over selected gating period and automatically scales the answer 10 108 or 10 clock periods repet itive bases fcode errors over 10 clock periods 0 0 x 107 to 1 0 x 107 code errors over 10 clock periods 6 0 48 10 to 1 0 x over 10 clock periods Indication given if measurement result based on less than 100 errors Totalises errors over selected gating periods Manual start stop pushbutton switches External control via printer output X Y x 10 LED with automatic round up 0 0 x 10 to9 9 x 10 Counts deviat
49. position and that a fuse of the correct rating is fitted 47 48 The POWER switch controls th ac power input to the instrument The LOGIC PROBE SUPPLY connectors provide power for alogic probe which may be required for the service or repair of the instrument Both and 5 volts are available and both supplies are inter nally fused at 200mA 3 15 OPTION CONTROLS AND CONNECTORS Option 001 003 Option 001 is the 16 bit word option and option 003 is the 16 bit word option with small Siemens connectors 49 3 6 The PATTERN SELECTION switch selects the pattern to be generated In the n 9 15 and 20 positions a maximal length PRBS of 27 is pro duced as for the standard instrument In the n 16 position the generator produces a repetitive 16 bit word whose content is selected with the WORD SELECT switches 51 18 the ALT posi tion the generator produces two 8 bit repetitive words A and B alternated by an external signal applied to the GEN ALT WORD HP connector 50 on the rear panel The word A is selected by a positive going transition of the input signal and the word B by a negative going transition SO The GEN ALT WORD I P connector accepts a signal to switch between words A and B as selec ted with the WORD SELECT switches 51 The input sensitivity is 250mV pk pk for a dc to 100 112 square wave or 0 5V for a 200Hz to 100k Hz sine or triangular wave The input imped ance is nominally 1K ohm and t
50. ptions 001 or 003 by setting the PRBS WORD switch to 16 and selecting the appropriate word with the WORD SELECT switches Systematic errors on the 4 or 16 bit words will then result in sync loss at the receiving instrument A typical example of the use of systematic error detection in an end to end measurement is given below Hf the transmitted word 1100 is repeatedly received as 1000 as the result of a systematic fault then the following results will be obtained with the receiving instrument PRBS WORD Switch Setting receiving instrument HESULT 9 15 or 20 NOERRORS WORD 1000 NO ERRORS WORD 1100 ERRORS SYNC LOSS An indication of receive pattern lock is given by LED lamps A manual override on the automatic sync is provided which forces a sync loss when released the instrument re verts to automatic synchronisation 1 43 Data and Clock Format The generator test pattern may be produced in binary RZ or NRZ or ternary HDB3 or HDB2 formats When operating in binary format a second binary output is avallable which is 6 bits advanced on the main data output The receiver data input format selection is independent of the generator controls 1 44 CLOCK or CLOCK may be selected independently on generator output and receiver input 1 45 A choice of trigger threshold is provided on clock and data inputs allowing continuous or burst mode operation indication of signal triggering is given by LED lamps 1 46 Error Counter Control an
51. r error free LIMITATION OF WARRANTY the foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by Buyer Buyer supplied software or interfacing unauthorized modification or misuse operation out side of the environmental specifications for the product or improper site preparation or maintenance NO OTHER WARRANTY IS EXPRESSED OR IMPLIED HP SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE mE EXCLUSIVE REMEDIES THE REMEDIES PROVIDED HEREIN ARE BUYER S SOLE AND EXCLUSIVE REMEDIES HP SHALL NOT BE LIABLE FOR ANY DIRECT INDIRECT SPECIAL INCIDENTAL OR CON SEQUENTIAL DAMAGES WHETHER BASED ON CONTRACT TORT OR ANY OTHER LEGAL THEORY Product maintenance agreements and other customer assistance agreements are available for Hewlett Packard products For any assistance contact your nearest Hewlett Packard Sales and Service Office Addresses are provided at the back of this manual PACKARD OPERATING AND SERVICE MANUAL 3780A o PATTERN GENERATOR ERROR DETECTOR Including Options 001 002 003 099 100 101 and 102 SERIAL NUMBERS This manual applies directly to instruments with serial numbers prefixed 2020U With changes described in section VII this manual also applies to instruments with serial numbers prefixed 1520U to 2006U For additional important information about serial numbers see INSTRUMENTS CO VERED BY MA
52. ree outputs which can be used to evaluate error distribution These are an error output giving one pulse per error 8 BCD printer output and a pen recorder output 1 52 OPTIONS 1 53 Option 001 provides front panel programmable 16 bit or two 8 bit words as described in Section 3 Para 3 15 1 54 Option 002 provides small Siemens connectors on all external 75 ohms interfaces in place of BNC connectors 1 55 Option 003 is a combination of options 001 and 002 1 56 Option 099 deletes frequency offset generation 1 57 Options 100 102 provide different crystal frequencies to those fitted in the standard instrument The frequencies available are listed in Table 1 2 Table 1 2 Internal Crystal Clock Frequencies 2048 8448 and 1536kHz 2048 8448 and 34368kHz 1544 6312 and 44736kHz 1544 6312 and 3152kHz STANDARD OPTION 100 OPTION 101 OPTION 102 In the case of options 101 and 102 the HDB3 HDB2 codec is replaced by a B6ZS B3ZS codec 1 58 ACCESSORIES SUPPLIED 1 59 Figure 1 1 shows the HP model 3780A and the acces sories supplied these are as follows Operating Manual 03780 9001 1 Operating and Service Manual 03780 20008 POWs Cable X dex aem rae ws see paragraph 2 12 and Figure 2 2 Extender Board fitted 03780 6002 1 behind board position 39 and fixed to the instrument sideframe with 3 screws Storage Cover a 03770 70096 Printer Output connector
53. rs 2 22 The connectors which mate with the front and rear panel BNC connectors vary depending on the diameter of the cable used Some examples of suitable connectors are given in Table 2 2 Front Rear Panel Connector Type GENERATOR Clock I P PRINTER O P 50 Pin Amphenol Inches Clock O P Data O P 7502 BNC 0 269 0 153 Delay Data O P RECEIVER Clock I P Data I P GENERATOR Trigger O P RECEIVER Rear Panel 5082 BNC 0 199 8120 0017 Clock O P Error O P Rec Trig O P For cable with connectors see paragraph 2 23 Installation 2 23 interconnecting Cables 2 24 A selection of 50 and 75 ohm interconnecting cables are available from Hewlett Packard Sales and Service Offices A cable stock number 562A 16C suitable for connecting the model 3780A printer output to an hp model 5055A 50508 or 5150A printer is also available Table 2 3 Mating Connectors Typical HP Stock Mating Connector HP Stock Number Number 8120 1289 8120 0049 1250 1448 1250 0629 1250 0533 1251 0086 Amphenol Type 57 30500 375 s 593 84939 4 40 291puj pue 103934105 05 0 jeueg AE pue 1u044 LE 988144 D s10 223uuoo pue s o1uoo uoudo sio 2ouuoo pue sjo1juoo 2604 sindjno Siojeorput Seu pue Ae dsrp S o1juoo juetuoinseour S1OjPOIpur uonpstuoiuou s pu 801 591 03 5849 8301339803 pu spo1juoo jndut 32 13597
54. s The pattern generator transmits a di gital test pattern into the system to be tested Simultan eously the error detector compares the output of the system under test bit by bit with an internally generated pattern Detected errors can be counted over a chosen gating period and displayed as bit error rate BER or total error count COUNT on an LED display 1 36 Code Errors The error detector can be used to monitor interface or line coded information for code errors These are detected during the decoding process and are counted and displayed in the same way as binary errors The information need not be a pattern produced by the generator 1 9 Model 3780A 1 37 Frequency Offset The clock frequency in the pattern generator may be offset and measured in the error detector receiver The offset is displayed as a fraction of the nomi nal crystal centre frequency The offset of external clock signals applied to the generator can be measured if the fre quency is within 25kHz of an installed crystal frequency 1 38 Frequency Control The generator and receiver may be operated from external clocks in the range IkHz to SOMHz The generator has three internal crystal sources in the range 1 5 50MHz which may be selected from a number of options The receiver clock can be recovered from incoming patterns af the frequencies installed in the generator The generator internal clocks can be offset by up to at least 50ppm except Op
55. t is tested see section IV of this manual 1 7 SAFETY CONSIDERATIONS 1 8 This Service Manual contains information cautions and warnings which must be followed to ensure safe opera tion and to maintain the instrument in a safe condition 1 9 INSTRUMENTS COVERED BY MANUAL 1 10 The contents of this manual apply to instruments with serial numbers as specified on the title page The in SERIAL NUMBER SERIAL PREFIX NUMBER Rm SOSDOSICODDO 4 SAO Figure 1 2 Serial Number Plate strument serial number is given on a serial number plate as shown in Figure 1 2 This plate is located on the rear panel of the instrument The serial number is in two parts The first four digits and the letter are the serial prefix and the last five digits are the suffix The whole serial number prefix and suffix should be quoted in any correspondance regarding the instrument 1 11 An instrument manufactured after the printing of this manual may have a serial number prefix that is not listed on the title page This unlisted serial number pre fix indicates that the instrument is different from those described in this manual blue Manual Changes supple ment supplied with this manual provides information on how to adapt the manual for such instruments 1 12 In addition to change information the supplement may contain information for correcting errors in the manual To keep the manual as accurate as possible Hew lett Packard recommen
56. t the generator DATA O P to the item under test If not using recovered clock connect the genera tor CLOCK OfP to item under test Set the RECEIVER BER COUNT switch Set the RECEIVER BER COUNT switch Set the ZERO ADD NORM ERROR ADD GATING lamp FLASHING DISPLAY 1 0x 107 GATING lamp FLASHING DIS PLAY 1 0x 107 NOTE measurement time 2 seconds GATING lamp ON After approximately 20 seconds OVERFLOW iamp ON OVERFLOW lamp OFF GATING lamp ON After approximately 3 minutes 20 seconds DISPLAY 9 8 x 107 3 34 Receiver 6 10 li 12 Connect data from item under test to receiver DATA I P if not using recovered clock connect clock from item under test to CLOCK I P Select DATA THRESHOLD 200mV 600mV or GND Select receiver CLOCK drive EXT EXT or RE COVERED Select INPUT FORMAT BINARY RZ or NRZ AMI or CODE Note The code will be the code selected with the rear panel CODE switch of the receiving instrument Select MEASUREMENT to be made CODE ERRORS or BINARY ERRORS If the generator pattern selected in step 2 was one of the fixed words and systematic error detection is required select the same fixed word with the PRBS WORD switch of the receiving instrument If sys tematic error detection is not required select one of the PRBS 9 15 or 20 positions of the PRBS WORD switch on the receiving instrument For HDB2 HDB3 code errors select vocabulary errors VO
57. tch f f or EI 6 Set the receiver MEASUREMENT to FREQUENCY OFFSET 7 Ensure correct operation by observing the display and GATING indicator Operation 3 38 To measure the offset of an external clock input connect the external clock input to the generator CLOCK I P and proceed as in steps 4 to 7 above 3 39 CONNECTION OF ASSOCIATED INSTRUMENTS 3 40 INTRODUCTION 3 4 The outputs provided for external recording or dis play of the measurement results are described in this sec tion The outputs covered are for a printer a chart recorder and a counter 3 42 PRINTER 3 43 The printer output is designed for direct use with a Hewlett Packard 5055A 50508 or 5150 printer The in formation from flag signals and display is presented for a 10 column print out in the form Bey WEN Where F represent the flag information and the remaining digits represent a BER or COUNT display in the form X Y x 10 t N The output information is in 8421 BCD form and print information between the error detector and printer is carried on two lines The error detector Printer output socket connections are as follows PIN NUMBER re x eve tos N 5 tone so e 7 8 48 alanla a ie ele elh ea KEY 1 2 4 8 BCD WEIGHTING D HIGH FOR LOW FOR LOW EXCEPT DURING SYNC LOSS OR OVERFLOW FLAGS F LOW EXCEPT DURING SYNC LOSS OR OVERFLOW FLAGS G GROUND PERMANENT HIGH INHIBIT 3780A C
58. the GENERATOR CLOCK O P and reconnect to the RECEIVER CLOCK I P Reset the RECEIVER CLOCK switch to EXE Set the WORD PRBS switch to 1111 options 001 and 003 to 16 with the WORD SELECT switches at 1111000000111190 Set the ZERO ADD NORM ERROR ADD Switch to ZERO ADD set the ZEROS switch to 006 options 001 and 003 set the zeros switch to 004 Set the RECEIVER INPUT FORMAT switch to AMI PRBS lamp ON DISPLAY 4 0x 107 Set the RECEIVER MEASUREMENT switch to CODE ERROR Set the OUTPUT FORMAT switch to AMI DISPLAY 00 x 10 Set the RECEIVER INPUT FORMAT switch DISPLAY 3 0 x 107 HD83 to CODE optians 101 and 102 1 0 x 107 6625 Set the OUTPUT FORMAT switch to DISPLAY x 100 CODE Reset the OUTPUT EORMAT switch to AMI DISPLAY 4 0 x 10 Set the rear panel CODE switch to HDB2 HDB and B3ZS options 101 and 102 5325 Set the OUTPUT FORMAT switch to CODE DISPLAY 0 0 x 10 Reset the rear panel CODE Switch to HDB3 options 101 and 102 5625 Reset the RECEIVER INPUT FORMAT switch to AMI Reset the OUTPUT FORMAT switch to RZ DISPLAY 4 0 x 107 Set the ZEROS switch to 996 options 001 and 003 set the ZEROS switch to 984 with the DISPLAY 4 0 x 107 WORD SELECT switches at 11110000 00000000 Continued on Page 3 11 Operation Table 3 5 Format Check Procedure continued Procedure Disconnect the cable from the GENERATOR DISPLAY 4 0x 1073 DATA O P and connect the
59. tic synchronisation system When the RE SYNC switch 15 pressed a search for synchronism is initiated The incoming pattern is examined for parity with each of the possible incoming patterns until less than 4 errors occur in 100 clock periods Synchronisation is then regained and the type of pattern indicated by one of the synchronisation indicators 27 to 30 27 PRBS The normal 2 1 2 1 or 2 1 bit PRBS produced by the generator di RC a 28 PRBS The inverse of the 2 1 2 or 2 1 bit PRBS produced by the genera tor 29 WORD Any word which is repetitive in blocks of 9 12 15 16 or 20 bits and all zeros any word sequence with less than 4 ones in 100 clock periods 30 AIS ALARM INDICATION SIGNAL being ali ones any word sequence with less than 4 zeros in 100 clock periods 3 11 MEASUREMENT CONTROLS Select measurements to be made display format and time base 3 4 31 The MEASUREMENT switch selects the measure ment to be performed In the FREQUENCY OFFSET Af f position the fractional difference between the standard and off set frequencies of rhe generator section is mea sured With the CLOCK SELECTION switch 1 set to OFFSET the fractional frequency differ ence measured is the off set selected with the OFFSET Af control 3 divided by the frequency selected with the FREQUENCY switch 2 In the CODE ERRORS position the receiver moni tors the input data at DA
60. tion 099 1 39 Pattern Selection Three maximal length pseudo ran dom binary sequences PRBS of length 511 32767 and 1 048575 bits and five four bit repetitive word patterns are produced by the generator The PRBS generator may also be used to generate random repetitive word patterns of length 9 15 or 20 bits 1 40 Option 001 provides a front panel programmable 16 bit word in place of the five four bit and random repetitive word patterns This can also provide two 8 bit words alter nated by an external signal applied via the rear panel 1 41 Up to 999 zeros can be added once per sequence to ali of the selectable patterns 1 42 When the PRBS WORD switch of the receiving instru ment is set to one of the PRBS positions or when the inter nal SYSTEMATIC ERROR DETECTION switch A37 82 set to OFF the error detector automatically recognises and reproduces a synchronous error free version of any PRBS or WORD pattern produced by the generator This inciudes PRBS but exciudes any pattern containing added zeros or alternating words Options 001 or 003 Instruments are supplied with the internal SYSTEMATIC ERROR DETECTION switch A37 S2 set to the ON posi tion In this mode the reference WORD of the receiving in strument can be preset to one of the fixed 4 bit words or with Options 001 or 003 to the 16 bit word This is achieved by setting the PRBS WORD switch of the receiving instru ment to the appropriate 4 bit word or with O
61. transitions pre sent Data Output CLOCK or CLOCK switch 75 ohms nominal to ground 3V 0 3V pk pk Space OV mark 3 V Less than 4ns Less than 10 of pulse amplitude Open short circuit protected max vol tage 2 6V short term PRBS WORD Zero Add Error Add Binary Ternary Codes Impedance Amplitude DC Offset Transition Times Overshoot Protection Maximal length 2 d f QP wp d E pan domly selectable 3 15 20 bit sequences 0000 1000 1010 1100 1111 fixed words 1 999 zeros variable in unit steps may be added once per se quence to any pattern Zero block occurs be fore longest run of zeros in maximal length PRBS 107 binary error rate may be added to any pattern 10 con secutive errors added every 1000 clock per jods NRZ or RZ 50 16 width on internal clock RZ AMI or coded 50 6 width on in ternal clock HDB3 or HDB2 rear pane switch 75 ohms nominal 10 ground Binary 3V 0 3 pk pk Ternary 4 74V 0 47V pk pk Binary space OV mark 3V Ternary space OV mark 2 37V Ratio of tve to ve pulse amplitude 1 0 t 0 05 Less than Ans Less than 10 of pulse amphtude Open short circuit protected max vol tage 6 V short term Format Relative Delay Delay Data Output DC Offset Table 1 1 Specifications continued Binary only Data Format 6 bits advanced on main data output Binary spac
62. urement when counting errors over 10 10 or 10 clock periods The STOP switch stops the measurement when counting over a manually controlled timebase The count is stopped by the switch being de pressed 3 12 DISPLAY AND FLAG INDICATORS Present the result and indicate state of measurement 35 36 37 The DISPLAY shows the measurement result Frequency offset measurements are displayed in the form XY x 10 Code error and binary error measurements ar displayed as BER in the form X Y x 10 or as COUNT in the form X Y x ID The GATING flag imdicates that a measurement is in progress The indicator will be off for at least 500ms between measurements The SYNC LOSS flag indicates 1088 of receiver pattern synchronisation The indicator is inhibited during code error and frequency offset measure ment Sync loss will also be indicated when the PRBS WORD switch 7 is in one of the fixed 4 bit word positions which is different to the word being re ceived With options 001 and 003 syne loss will be indicated when the PRBS WORD switch is set to 16 and the word selected with the WORD SELECT switches is different to the word being received Operation Note This does not apply if the PRBS WORD switch is set to one of the PRBS positions 9 15or 20 orif the internal SYSTEMATIC ERROR DETECTION switch A378S2 is set to OFF as the error detector will then syn chronise to any repetitive 9 12 15 16 or 20 bit
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