Digitizing Oscilloscopes (2009)
Contents
1. A short note about triggering and time is necessary at this point Triggering is actually a simple operation in principle For instance suppose you had a signal generator set to output a 2 Vp p sine wave hooked to channel 1 of an oscilloscope and had the oscilloscope set to trigger off of channel 1 at a level of O V with a positive slope This means that every time the input sine wave rises through O V the oscilloscope will register a new trigger event and uses that data to synchronize the waveform on the screen The time at which the trigger actually occurs is deemed to be t 0 by the oscilloscope Data displayed to the left of the trigger event is called pretrigger data to the right post trigger The time div setting controls how many cycles of the sine wave are actually displayed on screen In this case the sine wave s t sin t V would be displayed If the trigger level was increased to 500 mV then s t sin t 2 4 V would be displayed It s important to remember that it s still the same sine wave but that it is being displayed with a different t O point A digitizing oscilloscope is really just a fancy analog to digital converter A D with a display The oscilloscopes in the lab all have 8 bit A Ds which means that they can resolve 256 discrete voltage levels The levels themselves are dictated by the channel settings mainly volts div Most scopes have one A D and each channel shares it If you are examining so called2. e Sample SAVE RECA MEASURE AUTOSET e Peak detect UR OR usa a e Average o m o mii e Number to average 4 16 64 128 The Sample mode is the standard display format and the scope should normally be left in this mode The Peak detect mode is useful for examining waveforms that have glitches present These narrow glitches will be captured and displayed in this mode The average mode averages a set number of waveforms before updating the display The number to average is selected via the softkey directly under the average mode softkey The Display menu key will bring up the following items e Display type vectors dots SNE RECANEA PURE ACOUNE AUTOSET e Persistence off infinite ae m _ SOR Y OP TK e Display format YT XY pen iai cay pee Ee e Contrast increase decrease The display may be set to either the acquired samples themselves dots or to automatically interpolate fill the space between the acquired samples vectors Normally the display type is left set to vectors The screen persistence how long an acquired point is displayed may be set anywhere from off minimum persistence to infinite Several times are selectable in between these two extremes Revised Sept 2009 J Kowalski Page 11 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual The display format is normally left set to YT this is the normal volts vs time display of the scope When you wish to display
3. fast or high speed signals turn off all but one channel of the oscilloscope if possible to dedicate the A D within the scope exclusively to that signal Doing so will increase the sampling or resolution of that signal Each scope also has a bandwidth rating either 60 MHz or 100 MHz This number refers to the bandwidth of the analog electronics that precede the A D Revised Sept 2009 J Kowalski Page 1 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual There is one last important point to be made about the digitizing oscilloscopes They all have coaxial connectors known as BNC connectors they consist of an inner conductor and an outer conductor which is connected to ground internal to the scope When you connect a scope to your circuit with a BNC to alligator clip cable remember that the red clip is the signal connection while black clip is ground Wherever that black clip is connected will be grounded In terms of functionality that s really all there is to the operation of an oscilloscope What is more difficult to remember is where the controls are on all of the different oscilloscopes and where to find the specialized functions such as the x vs y display mode The specifics of each oscilloscope in the lab now follow HP 54600A 54601A 100 MHz Digitizing Oscilloscope Repetitive Bandwidth 100 MHz 20 MSample s 8 bit A D 2 channel HP 54600A 4 channel HP 54601A
4. The magnification button is used along with the horizontal scale and position knobs This is used to magnify and position the FFT spectrum Magnification is about the center of the display The entire waveform record is used to calculate the Revised Sept 2009 J Kowalski Page 15 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual FFT spectrum Magnification increases display resolution only The FFT spectrum is not recalculated Recall the factory setup before a new FFT spectrum is calculated Examples 1GS s sample rate for display Nyquist 1GHz 2 500 MHz BW 500 MHz 10 div 50 MHz div freq resolution 50 MHz 50 1 MHz 50 MS s sample rate for display Nyquist 50 MHz 2 25 MHz BW 25 MHz 10 div 2 5 MHz div freq resolution 2 5 MHz 50 50 kHz If want a 100 KHz BW which is 10 KHz div 100 KHZ nyquist X 2 200 KHz sample rate nearest higher sample rate 250 KS s Nyquist 250 KHz 2 125 KHz BW 125 MHz 10 div 12 5 KHz div freq resolution 12 5 KHz 50 250 Hz Agilent 54621D Mixed Signal Oscilloscope The 54621D is a combination oscilloscope and logic analyzer The digital section on the front panel is the logic analyzer part of the unit The analog section on the front panel is the oscilloscope part of the unit The oscilloscope section is labeled analog and refers to the type of input signal This is actually a digital oscilloscope with a c
5. 2 is set to 5 V div and is ac coupled In the top middle of the screen is an arrow and a time That is the time that corresponds to the middle of the screen in the current acquisition Just to the right of it you will find the current time div setting Somewhere along the top display line you will find an upside down solid triangle At the bottom of the screen you will find a right side up solid triangle immediately beneath it These triangles denote the t O point of the acquisition In the top right corner of the display you will find information about the trigger source mode and slope Lastly either RUN or STOP will be displayed to the right of the triggering information indicating whether the scope is actively acquiring data or has stopped Along the right edge of the display you will see a channel number along with a ground circuit symbol with an arrow pointing to the left That indicates the ground 0 V position for that channel If the ground position is off screen then the channel number and an arrow will be displayed at either the top or bottom of the screen to show where the ground level is Channel Menus and Vertical Controls Pressing either channel menu 1 or 2 brings up a list of items adjacent to the six softkeys at the bottom of the display These menu items are as follows e Channel off on ai demi e Coupling dc ac ground l e Bandwidth limit off on one A e Invert off on 2 e Vernier off on o
6. Digital channels always have peak detection on In Realtime mode the waveform produced is from samples during one trigger event A reconstructive filter is used to fill in the waveform displayed when less than 1000 samples are available in the time span of the display At sweep speeds of 200 nS div and faster less then 1000 samples are available on each trigger Realtime mode is only necessary at these sweep speeds Realtime is used to capture infrequent events or a changing waveform The waveform displayed with Realtime off is constructed from multiple triggers Averaging reduces noise The scope responds slowly to changes with averaging on Turn averaging off when adjusting the scope or changing signals High Resolution mode averages 1 is used when the sampling rate is faster then the rate at which the samples are being stored Samples are averaged together for each display point with this mode The slower the time div speed the greater the samples averaged Bit resolution will be increased at slower sweep speeds with High Resolution Single acquisition stores at least twice the number of samples then the Run mode Higher sampling rates occur at slower sweep speeds due to a larger memory available in Single mode Horizontal Measurements and functions are performed on display data The resolution of measurements and functions are affected by the resolution of the display Time div and volts div affect the resolution of the display A
7. along with other scopes and analyzers should be reset to factory default settings before using Press the Save Recall button and then the Default Setup button to reset This unit along with other scopes and analyzers has an Auto Scale button Auto Scale automatically configures the scope to display the signals at its inputs Students that use this function will not learn the basic controls and how to display signals The auto scale function can be misleading when displaying a signal In order to learn the operation of equipment avoid the Auto Scale button These units also do automatic measurements Manual cursor measurements are more accurate then automatic measurements Use the cursor measurements for accurate measurements and as a learning tool Measurements should be taken at the center of the trace width Quick Help gt Press and hold down the button which help information is required for gt Hold the button down to read gt Release the button to return to the previous scope state Trigger Mode Normal Mode gt Only Triggers when conditions are met transition or and a logic level Auto Mode gt Forces a trigger when conditions are not met Auto level gt Works with Edge trigger analog or external gt First it tries a normal trigger gt f no normal trigger is found then it searches for a transition signal and sets the trigger level at 50 of the magnitude gt lf there is no signal transition then it does an auto trigger
8. and forces a trigger In Auto or Normal mode a trigger will not be recognized until the pre trigger buffer is full At slow sweep speeds ms div the trigger may not be found Use Normal mode and wait for the trigger indicator to flash before causing the trigger condition in the circuit HF Reject is a 50 kHz input low pass filter to the trigger circuit Noise Rej increases the trigger hysteresis band thus reducing noise triggering This also reduces trigger sensitivity The signal may have to be increased Revised Sept 2009 J Kowalski Page 17 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual Holdoff keeps a trigger from occurring until the amount of time set has passed since the last trigger Used on a repeating pattern of a waveform to trigger on the same edge of the pattern Edge triggers on a falling or rising transition Pulse Width triggers after a time set pulse width has occurred Pattern trigger is a logical AND of the channels Channels can be specified high low or don t care X A rising or falling edge can be set for only one channel A trigger will occur when the specified conditions for all the channels is true Acquire Waveform In Peak Detection mode signals longer then 5 nS will be displayed at any time div speed This mode can be used at time div speeds slower then 1 mS div It has no effect at higher speeds as the scope will display 5 nS peaks in normal acquisition mode
9. one waveform vs another set the format to XY When in the XY mode channel 1 is the X horizontal waveform and channel 2 is the Y vertical waveform While in this display mode the channel 1 volts div and position knobs control the horizontal scale and position while the channel 2 volts div and position knobs control the vertical scale and position The contrast softkeys change the display contrast of the scope Measurements and Cursors A number of automated measurements are possible when the measure menu button is pressed svec ACQUIRE AUTOSET e Source Type e Any four of the following Oo CORPOR ee ee measurements frequency period mean average pk pk cyc rms true rms computed over one cycle rise time fall time positive width negative width or none The four measurement readout windows adjacent to the bottom four softkeys list the channel being measured CH1 CH2 the specific measurement as listed above and the measured quantity The top softkey selects between the source channel selection mode or the measurement type selection mode When Source is selected the source channels in the measurement windows become highlighted Pressing one of the bottom four softkeys will toggle the selected source channel but will not change the measurement type When Type is selected the measurement type will be changed by the bottom four softkeys but not the source channel A set of voltage or time cursors is available by pressing
10. retin e Probe 1 10 100 i If you select ground coupling for a channel that internally connects the input to ground If the bandwidth limitation is turned on the channel is low pass filtered with a cutoff of 20 MHz Invert does as you expect inverts the waveform When the Vernier is turned on the volts div for that channel changes in fine steps When it is off it changes in coarse steps Normally the Vernier is left off The volts div for each channel are adjusted using the large Volts Div adjust knobs Turn them counterclockwise to increase the volts div turn them clockwise to decrease it The position knobs control the vertical position of the waveforms on the screen by moving the ground position of each waveform up or down Revised Sept 2009 J Kowalski Page 3 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual Math Menu VERTICAL The math menu key brings up only three choices All three are oh self explanatory 5V 2m 5V 2mv Off e Channel 1 Channel 2 G F2 e Channel 1 Channel 2 Peston HE Postion H Timebase Horizontal Controls The delay knob adjusts the horizontal position of the display left or right by moving the t 0 point If the delay is adjusted then the pair of solid triangles at the top and bottom of the display mentioned previously will move accordingly The display point will retain a pair of open triangles to mark its
11. the Cursor menu button The following items then appear SAVE RECAMEASURE ACGURE 4 AUTOSET J e Cursor type off voltage time on z o T e Source CH1 CH2 MATH Ref VM om ie ii A Ref B ALTRIGGE oe T C 4 P ae The only deficiency that this scope has gt 09 HOLDOFF is its cursors Unfortunately only the voltage o w pe oH HOBEONTALTRIGCE or time cursors can be displayed but not both _ at once This may be an issue depending on the lab you are mente 3 a menu choices available here are self explanatory To move the cursors use the channel 1 amp 2 vertical position controls When either the voltage or time cursors are active the position of each cursor as well as the difference between them in either volts or seconds will be displayed at the right side of the display In the case of the time cursors 1 difference will also be displayed Printing Revised Sept 2009 J Kowalski Page 12 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual Unlike the HP oscilloscopes the TDS210 is capable of printing to many different types of printers with its three different hardware interfaces To print whatever is displayed on the screen you simply press oe oe Ae the HARDCOPY button However you oe must make sure that the scope is set up gt oe Wa gimis properly to use the selected printer The necessary information is found under the Options softkey menu displayed after pressing the
12. the scope The trigger source channel does not have to be on The trigger level control knob sets the trigger threshold voltage level for the selected trigger source When it is rotated a solid horizontal line will briefly appear on the display to graphically depict what voltage the trigger level is presently set to The trigger level in volts will be simultaneously displayed momentarily in the bottom left corner of the screen it will also show both the trigger source as well The Mode menu button brings up the following items Auto Level Auto Normal Single TV Auto level is the default triggering mode It sets the trigger point to the 50 amplitude point on the selected trigger source waveform If there is no waveform present a baseline is displayed Auto is a trigger mode that allows you to set the trigger threshold manually but like the auto level mode it will display a baseline if the trigger conditions are not met The normal trigger mode will display a signal only if a valid trigger signal exists that satisfies all of the trigger conditions If the trigger conditions are not met the display will not be updated The single trigger mode single shot triggers only once if the trigger conditions are met Once triggered the oscilloscope automatically goes into the stop mode and Revised Sept 2009 J Kowalski Page 5 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual must be rearmed befor
13. the type of input signal The oscilloscope has a band width of 100 MHz and a maximum sampling speed of 2 G Sa s 2 Giga samples second or a sampling frequency of 2 GHz The introduction part of the Digitizing Oscilloscopes and the Logic Analyzers in the Equipment Manual should be reviewed for basic theory operation The controls for the 6014A are similar to the HP 54601 oscilloscope and HP 54620A logic analyzer Refer to these sections in the Equipment Manual for an explanation of the operation and the controls This section is a supplement to the previous sections mentioned This unit along with other scopes and analyzers should be reset to factory default settings before using Press the Save Recall button and then the Default Setup button to reset This unit along with other scopes and analyzers has an Auto Scale button Auto Scale automatically configures the scope to display the signals at its inputs Students that use this function will not learn the basic controls and how to display signals The auto scale function can be misleading when displaying a signal In order to learn the operation of equipment avoid the Auto Scale button These units also do Revised Sept 2009 J Kowalski Page 19 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual automatic measurements Manual cursor measurements are more accurate then automatic measurements Use the cursor measurements for accurate measurements and as a
14. top of the screen indicates the position of this frequency The horizontal position Knob moves the display left or right and the Revised Sept 2009 J Kowalski Page 14 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual corresponding middle graticule frequency at the top of the screen will change accordingly At the bottom of the screen near the middle is the frequency div setting of the display Next to that in parenthesis is the current sampling rate used in computing the FFT At the bottom left of the screen is the vertical scale in dB div The volts div knob of the source channel for the FFT now controls the vertical dB div setting The choices are 1 2 5 10 and 20 dB div The vertical position knob of the source channel for the FFT controls the vertical position of the display The cursors may be used to determine signal levels and frequencies of the FFT spectrum Ensure that the source for the cursors is set to MATH Two types are then available magnitude and frequency As with the voltage and time cursors the positions of the two cursors are displayed in dB and Hz as well as the difference between the two Again as with the voltage and time cursors their positions are controlled by the two vertical position knobs for each channel Don t be fooled by the readout for the magnitude cursors the scope tells you the position of each cursor in dB but it s really dBV so keep that in mind To conver
15. A port on the front of the PC Start programs Electrical Engineering Lab Equipment Agilent DSO3000 Scope Click on the Connect to Oscilloscope icon in the tool bar Click on the Show Virtual Panel button in the DSO Controller window The scope can be adjusted from the Virtual Panel or DSO Controller window Push the Disconnect icon on the tool bar to disconnect the scope from the PC Push the Force button on the front of the scope to acquire manual control of the scope Revised Sept 2009 J Kowalski Page 24 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual Print the Display using Scope Connect The software must be controlling the scope Using the Waveform window push the Refresh button and uncheck the color box for the display Using the Waveform window push the Print button or the Export button for the output Revised Sept 2009 J Kowalski Page 25 of 25
16. Hz Digital Real Time Oscilloscope 60 MHz Bandwidth 1 GSample s 8 bit A D with 2500 point record length for each channel 2 Channel input and display Vertical sensitivity range 2 mV div 5 V div Horizontal sensitivity range 5 ns div 5 sec div Built in FFT Fast Fourier Transform capability for spectrum analysis TektrGnpO i iee x5 Ai a iia aia eee UTEITY CURSOR DISPLAY HARDCOPYRUN STOP VERTICAL HORIZONTALTRIGGER A POSITION A POSITION POSITION LEVEL CURSOR 1 MATAR lt HOLDOFF CHI H2 HOB ONTALTBIGER FORCETRIGGER an Key A ue TRIGGER VEW VOLTS DIV VOLTS DIV SEC DIV SET LEVEL TO 5 CH 1 CH2 EXT TRIG The TDS210 is the least expensive member of the Tektronix family of oscilloscopes Its size is small but it has very powerful performance Each input Revised Sept 2009 J Kowalski Page 8 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual channel has an input impedance of 1 MQ in parallel with a capacitance of 20 pF Each input may tolerate an absolute maximum of 300 Vims Like the HP 54600A 601A the TDS210 s display conveys a lot of information In the top left corner of the display is the Tek logo To the right of that you will find a picture of a square pulse This gives a graphical cue to the scope s acquisition mode Each mode has its own unique picture of a pulse Continuing to move to the right you will f
17. Manual Edge triggers on a falling or rising transition Pulse Width triggers after a time set pulse width has occurred Pattern trigger is a logical AND of the channels Channels can be specified high low or don t care X A rising or falling edge can be set for only one channel A trigger will occur when the specified conditions for all the channels is true There are many types of triggers for specialized waveforms in the More hard key category Consult the User s manual available from the technicians for the many types of triggers Logic Analyzer Digital Channels The Logic Analyzer cable connects to the rear panel Be Careful not to physically Stress the cable Route the cable around the side of the scope leaving plenty of slack at the rear of the scope Turn off the analog channels not in use Push the D15 Thru DO key Turn off the digital channels not used Controls for the digital channels are the soft keys below the display three keys to the right of the display and the Trigger keys The Thresholds soft key is used to set the digital channel threshold Printing the Display The display can be printed to a USB printer not available or to a USB mass storage device The USB storage device is available from the technicians in 2C94 Insert the USB storage device into the front connector Push the Save Recall hard key and then the Save soft key set the Format soft key to Print to Bmp 8 bit The Save To and File Name so
18. UTILITY menu button Three options are then available SAVE RECAMEASURE URE AUTOSET e Hard Copy Setup ce e RS232 Setup Gy o p tnapcommunsr e GPIB Setup Under the Hard Copy Setup menu you may select the orientation of the printout portrait landscape the printer format and the port Normally you would leave the orientation set to portrait If you have connected one of the HP ThinkJet printers then the format should be set to ThinkJet If you have connected the printer to the GPIB port then the port should set to GPIB A few of the HP ThinkJet printers have a centronics interface you should set the port to centronics if you use one of these printers There are also a few Epson style dot matrix printers available The format should be set to Epson and the port set to centronics in the event that you use one of these printers You can print to the HP ThinkJet printers with the GPIB interface using the TDS210 scopes but they take a very long time to print a waveform If you choose a printer with a centronics interface then printing time will decrease dramatically Stopping the display from acquiring new wave forms push Run STOP will decrease printing time Under the GPIB setup softkey lies another menu where you can choose the GPIB address of the scope and the bus connection mode Two choices are available off bus and talk listen Leave it set to talk listen at all times The RS232 setup softkey reveals another set of opti
19. University of Saskatchewan Electrical Engineering Laboratory Equipment Manual Digitizing Oscilloscopes 2009 This document is meant to be a reference to the operation of the digitizing oscilloscopes available in the laboratories Major topics will be covered but not all the features of the scopes will be outlined here Refer to the operations manual of the scope you are using for detailed information The operations manuals are available from the technicians in 2C94 All oscilloscopes whether analog or digital have similar operating principles and similar major controls Where they mainly differ is in their individual bells and whistles An oscilloscope is used to display voltage waveforms as a function of time These waveforms are usually cyclic in nature and the oscilloscope performs some processing on the waveform so that a stationary display is shown There are three major controls that dictate the way the waveform is displayed volts div vertical control time div timebase control and the triggering circuitry The volts div control dictates how big or how much of the screen the waveform occupies vertically The time div control dictates how many cycles or fraction of a cycle of the waveform are displayed horizontally The triggering circuitry is used to synchronize the display so that a stationary waveform is displayed The display may be triggered by a signal present at any of the oscilloscope s input channels
20. amined You control the position and size of the window with the horizontal position and time div knobs Once you have set the window to your liking select the Window mode to display only the data within the window on the full screen Beneath the display the window s time div is displayed preceded by a W To return to the normal display select the Main mode once again VERTICAL HORIZONTALTRIGGER The last menu item switches the Postion _ POSTION POSITION functionality of the trigger level holdoff knob It ees me o may be switched to control either the trigger C ii Me CH2 HORZONTALTRIGGER level or the trigger holdoff Normally this should be left set to level T VOLTS DIV SECIDIV SET LEVEL TC FORCE TRIGG Trigger Controls 44 4 4 4 TRIGGERVE As just explained above the trigger level holdoff knob controls either the trigger level threshold or trigger holdoff time depending on its setting in the horizontal menu Pressing the trigger menu button brings up the following items o posmion TES tin Raon S ALVEO S ede iace E e 1 TAPRSOR 2 _ HOLDOFF e Slope rising falling cH fe Ce fengont e Source channel 1 2 external external S AC line VOLTS DIV VOLTS DIV SEC DIV e e Mode auto normal single T FORCETRIGG e Coupling ac dc noise reject HF 4 4 4 A 4 4 TRIGGERVE reject LF reject For normal operation leave the scope in Edge trigger format Most items are self explanatory or are simil
21. ar to trigger options of the HP scopes which have already been explained Revised Sept 2009 J Kowalski Page 10 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual As with the other scopes a channel does not have to be on in order to be a valid trigger source When the trigger source is set to Ext a valid trigger signal must be connected to the EXT TRIG input on the scope The ac dc coupling option determines whether the trigger signal is ac or dc coupled to the trigger circuitry The noise reject option decreases the sensitivity of the trigger circuitry to help avoid false triggers on noisy waveforms HF reject low pass filters the trigger signal with a cutoff frequency of 80 kHz LF reject high pass filters the trigger signal with a cutoff of 300 kHz The button marked SET LEVEL TO ooo VERTICAL HORIZONTALTRIGGER 50 sets the trigger level to the vertical 0 lt D gt midpoint between the peaks of the trigger CURSOR 1 py THPRSOR2 HOLDOFF signal FORCE TRIGGER starts an acquisition GH1 M2 H REONTAL RIGGER even if a valid trigger signal has not been E LJ LJ detected TRIGGER VIEW displays the trigger VOLISDIV VOLTSDIV SECIDIV waveform as long as the button is depressed FC 5V 2mV 5V 2mV 5s 5ns Acquisition and Display Menus The Acquire and Display menus control how waveforms are displayed by the scope Pressing the Acquire menu button brings up the following items
22. athode ray tube display The oscilloscope has a band width of 60 MHz and a maximum sampling speed of 200 M Sa s 200 Mega samples second or a sampling frequency of 200 MHz Sampling Speeds 200 M Sa s 1 channel or 1 pod 100 M Sa s 2 channels or 2 pods or 1 channel and 1 pod Measurements should be done with unused channels and pods turned off The pods are used with the logic analyzer part of the unit Deep memory oscilloscopes can capture a long time event at a high sampling rate This allows a user to see fast details in a long event Memory Depth 2 MB for each analog channel 4 MB for a single analog channel in single mode 4 MB for each digital channel using 2 pods 8 MB for each digital channel using 1 pod Revised Sept 2009 J Kowalski Page 16 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual The memory is divided in half in the run mode This allows an acquisition of a record and a processing of the previous record This results in a fast display update The introduction part of the Digitizing Oscilloscopes and the Logic Analyzers in the Equipment Manual should be reviewed for basic theory operation The controls for the 54621D are similar to the HP 54601 oscilloscope and HP 54620A logic analyzer Refer to these sections in the Equipment Manual for an explanation of the controls An explanation of controls in this section is a supplement to the previous sections mentioned This unit
23. e it will reacquire data The run button must be pressed to rearm the scope The holdoff knob is a very important control as was stated earlier for the HP 54501A When it is rotated the trigger holdoff time is momentarily displayed at the bottom left corner of the screen Again a general rule of thumb is to set the holdoff time to be a little less than one period of the waveform you are examining if the scope is having difficulty triggering The Slope Coupling menu button brings up the following items e Slope rising falling e Coupling ac dc e Reject off lf hf low frequency high frequency e Noise reject off on The slope rise fall item selects whether the scope should trigger off of a rising or a falling edge that passes through the selected trigger threshold voltage on the trigger source channel The coupling selection allows you to choose whether the selected input signal should be ac or dc coupled before it is passed to the trigger circuitry The reject noise reject options are present to aid in triggering when examining noisy waveforms The LF reject option high pass filters the trigger signal with a cutoff frequency of 50 kHz The HF reject option will low pass filter the trigger signal again with a cutoff of 50 kHz The Noise reject option simply decreases the trigger sensitivity to help reduce the occurrence of false triggers caused by noise Display Measurements and Printing The Display menu button brings up the follo
24. ft keys may be used but it is not necessary The scope will assign incremented file names automatically Push the Settings soft key and select Invert Graticule Colors The Press to Save soft key maybe used or push the arrow soft key till the Quick Print soft key appears and select it This enables the Quick Print hard key allowing storage to the USB storage device without accessing the soft keys every time you Save Push the hard key Quick Print to save to the USB device Load the file from the USB device into a computer Delete your files from the USB device before returning it to 2C94 Revised Sept 2009 J Kowalski Page 22 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual Agilent DSO3102A Oscilloscope The introduction part of the Digitizing Oscilloscopes in the Equipment Manual should be reviewed for basic theory operation The controls for the 3102A are similar to the HP 54601 oscilloscope Refer to this section in the Equipment Manual for an explanation of the operation and the controls This section is a supplement to the previous section mentioned This unit along with other scopes and analyzers should be reset to factory default settings before using Press the Save Recall button and then toggle the Storage button till setups then press the Default Setup button to reset This unit defaults to 10X probe Probe setting is located in the analog channel menu 1 and 2 button The scree
25. gray Persistence is limited to the display area and not memory The Intensity knob allows a view of old acquisitions This is useful in viewing glitches The Intensity knob has no effect on digital channels Acquire key gt Realtime Default setting The display waveform is from the current acquisition only Not available in Average Acquire mode When less then 1000 samples are available to display a reconstruction filter is used to fill in the display Trigger Normal Mode gt Only Triggers when conditions are met transition or and a logic level Auto Mode gt Triggers when conditions are met or forces a trigger when conditions are not met In Auto or Normal mode a trigger will not be recognized until the pre trigger buffer is full At slow sweep speeds ms div the trigger may not be found Use Normal mode and wait for the trigger indicator to flash before causing the trigger condition in the circuit HF Reject is a 50 kHz input low pass filter to the trigger circuit Noise Rej increases the trigger hysteresis band thus reducing noise triggering This also reduces trigger sensitivity The signal may have to be increased Holdoff keeps a trigger from occurring until the amount of time set has passed since the last trigger Used on a repeating pattern of a waveform to trigger on the same edge of the pattern Revised Sept 2009 J Kowalski Page 21 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment
26. ind a status indicator If the scope is in the run mode a square with an R inside of it will be displayed Beside that is a status word relating to the trigger status of the scope Usually Ready or Auto will be displayed here If the scope is stopped a solid octagon stop sign along with Stop will be displayed The next bit of information that you find along the top of the display is the middle graticule time readout It displays the time to which the middle graticule corresponds The t O position is indicated by the upside down solid arrow at the top of the display At the bottom left corner of the display is a readout of the status of the input channels It indicates what channel s are on and what their volts div settings are To the right of this information you will find the main time div setting preceded by an M Finally in the bottom right corner is information regarding the trigger source trigger slope and trigger level At the left side of the display you will see the channel number 1 or 2 and an arrow pointing to the right This indicates the ground 0 V position for that channel At the right side of the display you will see another arrow pointing to the left This arrow graphically indicates the current trigger level Channel Menus and Vertical Controls Pressing either channel menu 1 or 2 brings up a list of items adierentt to the five softkeys at the right of the display These menu items are as fo
27. input and display Vertical sensitivity range 2 mV div 5 V div Horizontal sensitivity range 2 ns div 5 sec div hp HEWLETT 24600A 100 MHz STORAGE PACKARD OPE 2 CHANNEL Nessie eee ee a Run bas ae ae store Save Recall pen ogor idia TRIGGER o uaa _ Delay lt Level Auto Displ Print Ae pane BE Toa VERTICAL Volts Div Volts Dv Time Div er fo Va N BESA Slope g Coupling S lt S N A a a 5V 2 5V 2m 5s 2m FLE 2 Position Q Position m as poe C CJ J CJ L TO Trigger 1X 2Y Z 2 N a f N OON oO f Oo fo a J iou Se The HP 54601A is really just a two channel oscilloscope The two main channels are channels 1 and 2 with channels 3 and 4 being auxiliary or reduced performance inputs Each input has an input impedance of 1 MQ in parallel with a capacitance of 13 pF Each input may tolerate an absolute maximum of 400 V The HPIB connector is found on the back left side of the scope Revised Sept 2009 J Kowalski Page 2 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual The display of this scope conveys much information At the top left side of the screen you will find the channels that are on as well as their volts div setting and coupling For instance 1 2 00V 2 25 00V means that channel 1 is set to 2 V div and is dc coupled Channel
28. itions The Normal acquisition mode will capture a waveform when a trigger occurs Revised Sept 2009 J Kowalski Page 23 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual Sampling Modes The Real Time sampling mode is used for single shot and pulse waveforms This mode can be used for most signals The Equ Time mode is used for repetitive high frequency waveforms Trigger Edge triggers on a falling or rising transition Pulse Width triggers after a time set pulse width has occurred Video trigger is used for video signals Printing the Display The display can be printed to a USB printer not available or to a USB mass storage device The USB storage device is available from the technicians in 2C94 The mass storage device is connected to the USB host port on the USB module at the rear The mass storage has to be connected to appear in the Save Recall menu Display gt 2 gt Screen gt Inverted Save Recall Storage gt USB File Type gt Bit map Bmp Format gt 8 or 24 bit Save The problem with this method is the black screen is saved and not the inverted white screen Use the Scope Connect Software to print the screen 3000 Series Scope Connect Software This software interfaces the scope to a computer The GUI displays the scope screen and controls The scope controls can be adjusted form the GUI Connect a cable from the USB B port on the back of the scope to the USB
29. learning tool Measurements should be taken at the center of the trace width This scope will recognize the 10 1 probes and adjust the probe setting BW Limit is located in the analog channel menu This limits the bandwidth of the scope to 20 MHz This is used to filter out high frequency noise provided the signal is composed of low frequency components This is a very low bandwidth and will distort waveforms made up of frequencies components above 20 MHz It is best to leave BW Limit off in most situations Analog channel menu gt probe gt skew Skew is used to remove delays in probe cables between any two channels This can occur with time intervals in the nS range Attach both probes to the same point and adjust the skew between channels Quick Help gt Press and hold down the button which help information is required for gt Hold the button down to read gt Release the button to return to the previous scope state Main Delayed menu Main is the normal viewing mode for the display Delayed mode expands the main view In Delayed mode the top half of the display shows the main sweep and the bottom half shows the delayed sweep The delayed sweep is a magnified portion of the main sweep The magnified portion is adjustable using the Horizontal controls Single and Run Control The continuous Run mode uses half the memory to acquire data and the other half is used to process the previous acquisition Single acquisition mode uses
30. llows Coupling dc ac ground Bandwidth limit off 60 MHz on 20 MHz Volts div coarse fine 5 6 Probe 1X 10X 100X 1000X VOLTS D OLTS DIV Invert off on The volts div for each channel are adjusted by using the large VOLTS DIV adjust knobs The vertical position of the waveforms on the screen are adjusted with the small position knobs To turn a channel on off simply repeatedly press its channel menu button Timebase Horizontal Controls Revised Sept 2009 J Kowalski Page 9 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual The horizontal position knob adjusts the VERTICAL HORIZONTALTRIGGER horizontal position of the display left or right by PST Posmon AT moving the t 0 point The upside down arrow CURSOR 1 paran at the top of the display indicates the t O emo 2 HOLDOFF ALTBIGGER position and will move left or right as the O OA horizontal position knob is turned The large es VOLTS DIV ie SEC DIV knob adjusts the timebase of the a a ce scope eed nn eee TRIGGER VE The horizontal menu button brings up the following items e Main Window Zone Window e Trigger knob level holdoff The Main horizontal mode is the standard volts vs time oscilloscope display mode When the Window Zone mode is selected two vertical cursors are displayed on the screen They define a window that you can use to zoom in on a feature of the waveform s being ex
31. lways use the max volts div and sweep speed time div that fits on the display The Delayed sweep window is used to expand the waveform zoom The Delayed window shows a portion of the main sweep The display is divided in two Revised Sept 2009 J Kowalski Page 18 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual showing the main and expanded portion Peak Detection acquisition mode provides more detail when expanding the waveform The XY mode changes the scope from voltage versus time to voltage y Ch2 versus voltage x Ch1 Printing the Display The 54621D mixed signal scope can not print to the Think Jet printers or Scopecam The display can be saved to the front 3 5 floppy drive The floppies are available from the Technicians in 2C94 Push Utility and then the Print Confg soft key Push soft key Print to Disk Push soft key Format BMP image Soft key Factors set to off The scope is now set to print to disk Push the hard key Quick Print to save to disk Load the file from the floppy into a computer Delete your files from the floppy before returning it to 2C94 Agilent MSO6014A Mixed Signal Oscilloscope The 6014A is a combination oscilloscope and logic analyzer The digital section on the front panel is the logic analyzer part of the unit The analog section on the front panel is the oscilloscope part of the unit The oscilloscope section is labeled analog and refers to
32. n displayed menu appears when a hard key is pressed and will disappear 20 seconds default after use Do not change this time because it is hard to set with the display disappearing fast This unit along with other scopes and analyzers has an Auto Scale button Auto Scale automatically configures the scope to display the signals at its inputs Students that use this function will not learn the basic controls and how to display signals The auto scale function can be misleading when displaying a signal In order to learn the operation of equipment avoid the Auto Scale button These units also do automatic measurements Measure button Manual Cursor measurements are more accurate then automatic measurements Use the Cursor measurements for accurate measurements and as a learning tool Measurements should be taken at the center of the trace width BW Limit is located in the analog channel menu 1 and 2 button This limits the bandwidth of the scope to 20 MHz This is used to filter out high frequency noise provided the signal is composed of low frequency components This is a very low bandwidth and will distort waveforms made up of frequencies components above 20 MHz It is best to leave BW Limit off in most situations Acquisition Modes The Average acquisition mode will reduce the random noise of the waveform The average of 2 to 256 acquisitions is displayed The Peak Detect mode will capture the maximum and minimum levels of the acquis
33. o that they are as large as possible without going off screen and also ensure that they are each centered vertically in the display Make sure that each channel s coupling and probe are also properly set The time div should be adjusted so that at least one complete period is displayed horizontally select the XY mode to obtain a plot of signal Y vs signal X This display can be moved horizontally and vertically on the screen by using the channel 1 X position and Revised Sept 2009 J Kowalski Page 4 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual channel 2 Y position controls The volts div settings for each channel found in the upper left corner of the display tell you the voltage scale readings in the X channel 1 and Y channel 2 directions To return to the standard volts vs time display mode select the Main softkey in the Main Delayed menu When on the Vernier control acts like a fine adjust for the time div knob Normally this control is left off The time reference position control is self explanatory Trigger Controls HORIZONTAL The Source menu button brings up the following items e Channel 1 Delay 5 e Channel 2 a e External Trigger Ext Tine Dw e Line The choices are self explanatory except perhaps for Line Line iS s 2s the supply line voltage If Ext is selected a signal must be connected to the Ext Trigger input on the front panel of
34. ons Leave all fields set to their default values press the Set to defaults softkey these default values are sufficient for your needs Math Menu Pressing the math menu button will automatically switch the scope to the math function currently selected There are three major functions addition subtraction and FFT fast fourier transform or spectrum analysis Depending upon which function is active a different set of softkey choices will be available However the mathematical operation selection softkey is a Nae ad welt VERTIC _ POSITION POSITION Z i Z VOLTS DIV VOLTS DIV Revised Sept 2009 J Kowalski Page 13 of 25 K x 5V 2mV 5V 2mV University of Saskatchewan Electrical Engineering Laboratory Equipment Manual the first available choice for all three In the case of addition no further choices are available only CH1 CH2 For subtraction there are two choices CH1 CH2 or CH2 CH1 To turn the math function off simply press the math menu button again Only the basic instructions regarding the FFT will be presented here For more information consult the TDS200 Series Extension Modules manual The fast fourier transform is a mathematical function that takes a set of discrete numbers as its input In this case those numbers are the discrete sampled points of the input waveform The FFT requires that the number of samples it receives be a power of 2 The oscilloscope captures 2500
35. points per waveform but only the middle 2048 are used to perform the FFT Before you perform an FFT on a waveform be sure that it is vertically centered in the display and is as large as possible without clipping or going off screen Also make sure that several cycles of the waveform are displayed Now turn on the FFT by pressing the Math menu button and selecting the FFT operation You may select the channel on which to perform the FFT CH1 or CH2 the window type to apply to the data and the FFT zoom level There are three window types that you may choose Rectangular Hanning and Flattop Without delving into the underlying theory the following table summarizes the characteristics of each window type Characteristics Hanning Periodic waveforms Better frequency poorer magnitude accuracy than Flattop than Hanning Special purpose window for waveforms that do not have discontinuities Same as no window The FFT zoom level X1 X2 X5 X10 changes the horizontal magnification of the FFT display The FFT display is calibrated in dBV decibels referenced to one volt rms The level of a signal in dBV is given by the following formula Signal Level dBV 20 log Vims 1 V Where Vms is the rms voltage of the signal The oscilloscope display changes slightly when the FFT function is active At the top of the screen is a readout that displays the frequency corresponding to the middle graticule The upside down arrow at the
36. position The display point may be set to either one graticule in from the left side of the display or to the center of the display TRIGGER a Level me Holdoff Slope Coupling The time div or timebase is adjusted by the large Time Div knob Turn it counterclockwise to increase the timebase clockwise to decrease it Pressing the Main Delayed menu button will bring up the following items e Horizontal mode main delayed XY e Vernier off on e Time reference position left center The Main horizontal mode is the standard volts vs time oscilloscope display mode The Delayed mode splits the screen into two in the top portion are the original waveform s and the bottom holds a time zoomed version of that waveform s The Time Div and Delay knobs control the window size and position of the zoomed portion The XY mode is very useful and is something with which you will become very familiar in the labs Technically the XY mode should be named YX mode since the Y signal is plotted as a function of the X signal However the standard among scopes is to name these modes XY so we must stick with that same standard The X horizontal signal is connected to channel 1 and the Y vertical signal to channel 2 The X and Y are also printed beside the channel 1 and 2 inputs on the front panel should you forget what gets connected where While still in the Main display mode adjust the vertical controls of each signal s
37. rs varies with the selected measurement Pressing the Time menu button brings up the following options e Source for the measurement channel 1 or 2 e Frequency Period Duty Cycle Width Width Risetime and Falltime as with the voltage measurements the first 3 are found on the first page of the menu with the rest on the following page e Clear Measurement Revised Sept 2009 J Kowalski Page 7 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual e Show Measurement off on If you ever need to perform voltage or time measurements yr m other than the automatic ones listed above there are a set of voltage and time cursors available when the Cursors menu button is pressed j It will bring up the following items e Source for the cursors channel 1 or 2 sae P Gi e Active cursor V1 V2 t1 t2 e Clear Cursors When a particular cursor is selected by an active cursor softkey it may be moved by using the unmarked knob underneath the Cursors menu button Cursors should be placed on the scope trace at the centre of the trace thickness Its present value location in volts or seconds is displayed underneath the waveform display area of the screen as well as the present value of the other voltage or time cursor The difference between the two cursors in volts or seconds is also displayed In the case of the time cursors 1 difference is also displayed Tektronix TDS210 60 M
38. s menu Obviously you would select connect to HP print if the scope was connected to a printer If you connect it to a computer then you would select computer The instrument s address is displayed above the address softkey Pressing that softkey increments the address by 1 Possible addresses are 0 30 When factors are on the oscilloscope will also print extra information regarding the waveforms underneath the screen plot Normally factors is left off The resolution should be set low to function properly with the printers available in the labs A variety of automatic voltage and time measurements are available through the Voltage and Time measurement menu buttons Pressing the Voltage menu button brings up the following options e Source for the measurement channel 1 or 2 e Vp p Vavg Vrms Vmax Vmin Vtop ANd Vpase the first three are available on the first page of the menu while the last four are available by hitting the Next Menu softkey e Clear Measurement e Show Measurement off on Save Recall Auto Display Print scale Utility The Clear Measurement option will erase any selected measurements The Show Measurement option displays cursors on the screen when on For example if the measurement Vp p is selected two horizontal cursors that are locked to the topmost and bottommost parts of the selected waveform will be displayed on the screen The location of these curso
39. t signal levels in dBV to rms volts Signal Level Vims 49 Signal level dBV 20 Tektronix TDS 3012B Oscilloscope FFT Math Function This function converts an oscilloscope time domain waveform into its frequency spectrum Waveforms with a D C component may cause errors in FFT magnitudes Push the Save Recall button Recall Factory Setup button and the Confirm button Connect the source to the scope and display the time domain waveform The acquisition mode should be set to sample and the horizontal resolution should be set to normal These are found in the Acquire menu The Acquire menu also displays the sample rate Push the CH 1 and menu buttons AC coupling is preferred The bandwidth can be set to 20 MHz This filters the source signal limiting frequencies below the nyquist frequency Full band width is 150 MHz Use the fine scale button so the waveform uses approx 95 of the vertical scale The horizontal scale knob should be set to display a minimum of five periods This controls the sampling frequency and the frequency resolution The more cycles displayed increases the frequency resolution and decreases the sampling rate This is the trade off The nyquist frequency is half the sampling frequency Aliasing may occur if the sampling rate is low Push the math and FFT buttons for the frequency spectrum The rectangular window is the only non windowing function Non windowing is used for transients Periodic waveforms require windowing
40. twice the memory as the Run acquisition mode The increase in memory allows for a high sampling rate at slower sweep speeds Single acquisition will acquire data with the longest record So use the Single acquisition mode for maximum sampling rate and memory depth Set the trigger mode to Normal and the trigger level high enough so the desired event will trigger the acquisition and not a low level event The scope will otherwise immediately trigger Revised Sept 2009 J Kowalski Page 20 of 25 University of Saskatchewan Electrical Engineering Laboratory Equipment Manual Acquire Modes Normal gt Best for most waveforms No averaging Default setting gt At slow speeds extra samples are discarded Peak Detect gt Best for capturing narrow pulses gt At slow speeds extra samples are kept to capture narrow pulses gt Displays pulses as narrow as 500 pS High Resolution gt At slow speeds extra samples are averaged to produce a point gt Limits the scopes real time bandwidth acts as a low pass filter Average gt Averages acquisitions to reduces noise gt Bandwidth and rise time are not reduced At slow sweep speeds the sampling rate decreases due to an increase in acquisition time Sampling is faster then what is required to fill the memory Push the Main Delayed key to display the sampling rate Display key gt Infinite Persist The display is updated with new acquisitions and old acquisitions are displayed in
41. wing items Woe Te a e Display Mode normal peak detect average _ e Grid off on fee eee These items are self explanatory except perhaps for the peak Cy detect mode This is a specialized display mode that is useful in identifying glitches in the waveform s you are examining These signal extremes are identified and saved if the time div is set longer than 50 us div At lower time div settings this display mode is disabled When the average display mode is selected a new softkey selection to choose the number of waveforms to average is displayed The choices are 8 64 256 The Print Utility menu button brings up the following items e Print Screen e HP IB Menu re e Clear Menu 6 Self Test Menu Aig omy Revised Sept 2009 J Kowalski Page 6 of 25 leasure oo Te kaa University of Saskatchewan Electrical Engineering Laboratory Equipment Manual e Self Calibration Menu The only options you should be concerned with are print screen and the HP IB menu Print screen is self explanatory You must connect a printer to the scope via the HPIB connector on the rear of the scope and the printer must be on and online The entire display will be printed when the print screen button is pressed Pressing the HP IB Menu softkey will bring up another menu with the following items Connect to computer HP print HP plot Factors off on Resolution low high Address Previou
Download Pdf Manuals
Related Search