Beginners` Guide to the TDS 210 and TDS 220 Oscilloscopes
Contents
1. I would like to thank the members of the 1999 2000 ELEC 290 class here at Queen s University who along with myself learned how to use this oscilloscope this year and gave me many of the ideas for this guide Please send any ideas for improvements to this guide to me at david lay ece queensu ca David Lay Department Engineer Electrical and Computer Engineering Queen s University at Kingston Ontario Canada 1 August 2000 ELEC 290 Lab Manual E3 16 Fall Term2. 00s MEASURE a a a re Ss SUITE See eves sees sees eee eee ae Vere oe ee ear Beware eee eee CH1 eee EE EEE E E TE free 1 000kHz A TETTE TICE TIT A TTE TTE TICE TIT 334 33 333 334 CHI 2000Y CH2 500m M 2500s CH1 wf 232W If the peak to peak voltage is not close to 5 volts in particular if it is around 0 5 or 50 volts the probe setting of the oscilloscope is incorrect The oscilloscope displays voltage values based on the probes The probes improve the performance of the oscilloscope by increasing the effective input impedance from 1 Megohm to 10 Megohms thus reducing the loading effect that the oscilloscope has on the circuit In doing so the probe reduces the input signal by a factor of ten For example if a three volt signal is present at the probe tip 0 3 volts appears at the oscilloscope input channel connector The oscilloscope compensates for this attenuation when it takes voltage measurements Since the oscilloscope cannot detect which type of probe is connected to any input channel you have to tell the oscilloscope through a channel menu selection The most common probe attenuates the signal 10 times and is called a 10X probe The oscilloscope includes 10X probes although you can also use 100X and 1000X probes 7 Press the appropriate channel menu front panel button such as CH 1 MENU The Probe menu item appears beside the fourth bezel button succes
3. Beginners Guide to the TDS 210 and TDS 220 Oscilloscopes By David S Lay P Eng Foreword This guide contains information to help you become familiar with using digital oscilloscopes You should work through these lessons if you have limited knowledge of oscilloscopes or if you have only a basic understanding of simple analog oscilloscopes The lessons in this guide will help you in the following ways e Quickly be able to use a digital oscilloscope e Avoid some of the traps that you may fall into e Avoid advanced functions that may get in the way of taking simple measurements To gain the most from this guide you should use it while you work through each lesson with the TDS 210 or TDS 220 oscilloscope and a function generator Credits Oscilloscope drawings are reproduced by kind permission of Tektronix Incorporated The drawings in this guide are of the TDS 220 oscilloscope which is functionally identical to the TDS 210 except that it has 100 MHz bandwidth compared to the 60 MHz of the TDS 210 The screen shots were captured using Wintek32 a freeware product of Production Robots Ltd Wintek32 can be found on the Tektronix web site www tek com as thsdump zip The next drawing shows the front of a TDS 220 oscilloscope Tektronix TDS 220 Soa Eime ouor D CH2 J i an bna CH1 TRIG HOOO Copyright 2000 David S Lay ELEC 290 Lab Manual
4. E3 1 Fall Term Lesson 1 Getting Started This lesson teaches you how to turn on the oscilloscope and display a simple signal To perform the Getting Started lesson follow these steps 1 Plug in the oscilloscope and apply power by pressing the POWER button on the top of the case Notice that when you apply power the oscilloscope immediately performs a self test 2 Wait until the display shows that all self tests passed and press the SAVE RECALL front panel button top left The SAVE REC menu displays on the right of the screen The top right bezel button toggles between two menus Setups and Waveforms 3 Be sure that Setups is highlighted in inverse video and press the button beside Recall Factory The oscilloscope recalls the default factory settings to initialize the instrument to a known state which eliminates any nasty surprises If at any time you do not understand what the oscilloscope is displaying you can repeat this step The box at the end of this lesson also gives some suggestions for getting out of odd screen modes without resetting everything The display that dominates the left side of the scope is a digital LCD screen This means that displayed signals have visible pixel jaggies If you have used an analog scope you will notice that the signals especially sine waves do not look as smooth and continuous on this screen The digital display does however have some significant advantages as you wi
5. Usually you will connect the probes here but you can also use a coaxial cable with a BNC connector to connect the scope to a function generator or other signal source Immediately to the left of the inputs is a pair of small metal tabs labelled PROBE COMP for probe compensation This is an internal source of a square wave at about 5 volts magnitude and 1KHz used to adjust the internal compensation of the probe 4 Connect the probe on channel 1 of the scope to the top tab and the ground clip of the probe to the bottom tab 5 Press the AUTOSET button near the top right corner on the front panel The oscilloscope sets the vertical horizontal and trigger controls automatically which usually results in a usable display These settings are adequate in this and many other situations Be aware that the oscilloscope also sets a number of background functions that might be not be desirable in some circumstances Depending on how the oscilloscope was being used when it was last turned off you may see one or more channels displayed The trace labels on the left edge of the screen correspond to the channel numbers on the front of the oscilloscope 6 If only one channel appears press the CH 2 MENU front panel button to display channel 2 and then press AUTOSET again Now both channels display even though there is nothing but noise on channel two The upper trace should show a steady square wave as depicted below The wave is stationary on the sc
6. e at the left edge of the screen Press the SAVE RECALL button Use the third screen button to select Ref A or Ref B if necessary then press the bottom button to turn it off ELEC 290 Lab Manual E3 5 Fall Term Lesson 2 Measurements In general you will use an oscilloscope to measure characteristics of a signal such as magnitude or period of oscillation You can look at the signal in relation to the screen grid or graticule to estimate the values of these characteristics which was about one could do with early oscilloscopes Modern oscilloscopes have much more powerful measurement capabilities In this lesson you will learn about the following topics e How to use the Measure menu to define the source and type of measurement to take e How to set the Probe menu item to match the probe in use e The difference between measuring a signal and a displayed waveform Lesson 2 begins where lesson 1 ended If the oscilloscope has been turned off or the settings changed since lesson 1 you need to quickly redo lesson 1 to get back the centred square waveform that fills most of the screen with two or three full cycles displayed To perform the Measurements lesson follow these steps 1 Press the MEASURE front panel button The word MEASURE appears above the menu area Type is the active menu CH1 is the source for four measurements and no measurements are selected NONE The Measure menu is a Page Selection type of m
7. e the VOLTS DIV front panel knobs to set channel 1 to ho Q d 1 volt per division and channel 2 to 500 mV per division i 9 These numbers appear near the bottom left corner of the pO a delim Saat A Ain screen OO 5v 2w 13 Use the POSITION front panel knobs to adjust the vertical positions so that both waveforms are on the screen You za S 5 might have to reduce the function generator output slightly M to fit the channel 2 waveform 555 EXT TRIG 14 Press the MATH MENU front panel button between two Vertical POSITION knobs If your oscilloscope has a TDS2MM extension module the FFT module installed the Math menu will be different See the user manual that comes with the TDS2MM module for the changes to this procedure 15 Press the top button CH1 CH2 Tek JL Stop M Pos 0 0005 MATH the left of the screen eet Oe AE E ete A E EE Y a k g lt a i F CHT tony thr iim M siis CR TW display might look ELEC 290 Lab Manual E3 11 The oscilloscope removes the two channel waveforms and displays a new Math waveform labelled M at The Measure menu does not measure Math waveforms However you can E E AE A ae CHI take measurements from Math Poalogleslesloslaclocloclec loo Inverted waveforms with cursors Inverted This shows how the oscilloscope Fall Term Using the Cursor Menu To use the Cursor menu to measure a Math waveform follow these
8. enu The top menu displays two menu names Source and Type The active menu is highlighted in inverse video white letters in a black box When Source is highlighted you can press each of the other four bezel buttons to switch between CH1 and CH2 as the measurement source When Type is highlighted youcan press each of the other four buttons to select the type of measurement to take from the selected source 2 Press the second button until Freq appears A question mark appears momentarily until the oscilloscope measures the frequency of the signal connected to CH1 3 Press the third button until Period appears The oscilloscope displays the period of the signal 1 f 4 Press the fourth button until Mean appears The oscilloscope displays the mean voltage 5 Press the fifth button until Pk Pk appears The oscilloscope displays the peak to peak voltage 6 Press the third button until Cyc RMS appears The oscilloscope displays the true RMS value of one cycle of the waveform ELEC 290 Lab Manual E3 6 Fall Term The Freq Period Mean Pk Pk and Cyc RMS measurements are always available If you have a TDS2MM module in your oscilloscope then there are some other measurements available that we will not cover here such as rise time The next drawing shows how the oscilloscope display should now look There may be some variation in the actual measurement values caused by subtle fluctuations in the source signal Tek tL Sto M Pos 00
9. ll discover Some of the information around the edges of the display will be explained as we go along the rest can be looked up in the Tektronix manuals The large area down the right side of the screen is the menu A large number of menus are available and are called up by pressing various buttons on the control panel The buttons immediately to the right of the screen correspond to the menu items their functions change depending on the menu displayed Take a close look at the probes that are provided with the scope These are important to the performance of the oscilloscope and should be handled with care The sprung hook tip is removable revealing a point that can be used in tight locations The short wire that terminates in an alligator clip is the ground connection If both probes are connected to the scope disconnect one of them by turning the connector to the left and pulling it straight toward you ELEC 290 Lab Manual E3 2 Fall Term Take a look at the connector and note that it is not quite like a regular BNC connector on which the shell will rotate continuously This connector only turns through a small arc and must be in the left or unlocked position before being pushed onto the oscilloscope input Do this now and turn the connector to the right to lock it Now we will get a signal onto the display Note that the first two BNC type connectors at the bottom edge of the front of the scope are labelled CH 1 for channel 1 and CH 2
10. loscope display should now look Ek th de cc een EELS 95 Set the Source menu item to ar E Setups CH2 the Ref menu item to B ak and press the button next to the Source Save menu item to save the i CHI channel 2 waveform as reference Ref B 6 Set the last menu item Ref B to Save On olosiosb Snn ee ee eres pe 7 toveben geoi Hania frequency to 30Hz and change the time base to 10 ms per division CH1 J 0 004 Note that Ref B appears as a grey trace You can make the 1 2 and B labels visible at the left edge of the screen by moving the channel and 2 waveforms vertically Note also that when you change the time base the active traces change scale but Ref B does not The time base of a reference waveform always stays at the value that it was saved at This is important to remember for reasons that we are about to discover 8 Turn Ref B off and reset the vertical positions of channels 1 and 2 to zero Remember that there is a readout of the vertical position that appears at the bottom left corner of the display while you are moving either of the vertical position knobs Using Cursors to Measure Time Now we will use the cursors to measure the time difference between the two waveforms To do this follow these steps ELEC 290 Lab Manual E3 14 Fall Term 1 Press the CURSOR front panel button 2 Press the Type bezel button and select Time Two vertical lines appear on the screen the time cursors 5 Tur
11. mber for the future when interpreting peak to peak values Now we are going to deliberately cause an erroneous reading Tek JU Stop M Pos 168 0us Measure 9 Tum the Horizontal SEC DIV knob a Peete tae By ty Oa Source time base control until the time The oscilloscope no longer displays values for frequency or RMS voltage because there is not a full cycle to measure on the screen but the mean voltage has not significantly changed CHT Sy te iim eiis OT a knob to move the waveform to the left while reading the mean voltage The mean value steadily increases reaching close to the peak voltage when the trigger point is at the left side of the screen The mean value of the signal has not actually changed what has changed is the mean value of the part of the waveform that is displayed which is the point of this exercise The measurement functions of this oscilloscope and digital scopes in general operate on the displayed waveform not on the input signal and must be interpreted with care ELEC 290 Lab Manual E3 8 Fall Term Lesson Three Advanced Measurement Techniques the Math and Cursor Menus In this lesson you will learn about the following topics e Why the oscilloscope must connect to the same ground point as the circuit under test e How to use Math menu functions to measure the voltage of two signals that are not both connected to the same ground e How to use the Cursor menu functions to measure a Math wavef
12. n expand it for a better view The bottom knob of the channel or vertical controls is the volts per division range control Turning the VOLTS DIV knob to the right increases the sensitivity decreases the volts per division and expands the display vertically One division is the distance between the grid lines on the screen a bit less than one centimeter apart Just to the right on the other side of the channel 2 controls is a similar knob labelled SEC DIV that controls the time base resolution Turning it to the right reduces the time per division and expands the display horizontally Quick fixes for display problems These relate to features that we will study later but may be just getting in your way right now My display is very dark or has very low contrast Press the DISPLAY button The bottom two buttons at the right edge of the screen are now labelled Contrast Increase and Contrast Decrease These actually lower and raise respectively the brightness of the white part of the screen As soon as you press one of them the contrast level appears at the bottom right corner Set it to 50 There are a pair of extra vertical or horizontal lines cluttering up my display Press the CURSOR button The top button at the right of the screen is now labelled Type and will have either Voltage or Time below it Press it until it says Off There is an A and or a B with or without an associated trac
13. n the Horizontal SEC DIV knob to set the time base to 2 5 ms per division stretching out the waveform allows a more accurate time measurement 6 Use the CURSOR 1 and CURSOR 2 Position knobs to place Cursor 1 on the point where the channel 2 waveform the one on the left change the VOLTS DIV temporarily if you want to confirm this crosses the zero line going upwards and Cursor 2 where the channel 1 waveform passes upwards through zero Tek fl Stop M Pos 0 000s CURSOR L The Delta now shows the time e e ee ae ee difference between the zero crossing ears points which is the amount of time Source that channel 1 lags behind channel 2 CHI Delta The drawing to the left shows how cae Te the oscilloscope display might look Poolo preedecerierecdeertiene Cursor 1 J 4100ms The Source for this measurement may be set to CH1 or CH2 since both channels are always on the same time base However set the Source to Ref A and watch what happens to the Delta number Cursor 2 400 0 u5 It s about twice the previous reading because the reference waveforms were saved with the time base set to 5 milliseconds per division and now it is set to 2 5 ms div The cursor reading is correct for a measurement on reference signals A or B but not on channels or 2 even though neither Ref A nor Ref B are displayed Whenever you use cursors you must always ensure that the Source setting matches the waveform that y
14. ngs that Autoset changes see the Tektronix manual for the complete list and use Autoset wisely e Before proceeding switch the probe compensation waveform back to channel 1 ELEC 290 Lab Manual E3 4 Fall Term Now let us get rid of the useless channel 2 display and expand the channel 1 presentation 7 Press the CH 2 MENU front panel button to remove the channel 2 waveform from the display If that channel s menu is not already displayed the first push of the button displays the menu the top right corner of the screen will say CH1 or CH2 A second push turns off the channel Do this and you should see that the channel 2 trace disappears Now look at the channel 1 control area In addition to the CH 1 MENU front panel button there are two knobs The top one controls the vertical O o ojo position Im m VERTICAL HORIZONTAL A rosmon rosmon gt 6 L6 S 8 Turn the POSITION knob to bring the displayed waveform Fae HORIZONTAL MENU wol down to the middle of the screen vomon vomon sew i a Note that as soon as you start turning the knob a line of text ee appears in the bottom left corner of the screen This is telling moe cH1 dia Tarma you how far the zero level of this channel is from the vertical center of the screen There are several reasons why you might want the display exactly centred and this helps you to do that Once you have the trace centred you ca
15. o peak reading for channel 1 This shows an example of how the Tek tL Stop M Pos 0 000s MEASURE ye at na a eaae FORE oscilloscope display might look area a E Eaa a a oe bee ALY PY GL GGT TL Yt om The peak to peak reading for channel 1 E 2 should be about within the Ecks kebes EE E ns RE i i z tolerance of the resistors two thirds ap IE IE IE IE IE IE vk 1E CH A M M AM oaao gag ofthe peak to peak reading for yg ag iy pig a a F Channel 1 We have successfully m measured the voltage across the 2 a aa a a YOI Pay Romer Grey Renee Sia We Sar a ae a 3 92 20KQ resistor Let s try to measure MED MED MD MEME ME ME MEM CH2 the voltage across the 10KQ resistor None CHT 2 00 CHA 2 00 Mims CHT 0 00 ELEC 290 Lab Manual E3 10 Fall Term 10 Connect the channel 2 probe to point A and its ground clip to point B What does the oscilloscope now read for the channel 2 voltage It should be the same as channel 1 because we just shorted out the 20KQ resistor Fortunately there is still a high resistance in the circuit this sort of mistake could be dangerous if we were working with high voltages and low resistances 11 To get a correct reading re connect the channel 2 probe to point B and its ground clip to point C Channel 2 is once again measuring the voltage at point B To measure the across the 10KQ resistor we must determine the difference between channel 1 and channel 2 12 Us
16. obe to the CH2 BNC connector 2 Press the CH1 MENU front panel button and select 10X for the Probe menu item 3 Press the CH2 MENU front panel button and select 10X for the Probe menu item ELEC 290 Lab Manual E3 9 Fall Term 4 Build the following simple circuit Function Most function generators are grounded so Generator point C is at ground potential If your function generator is not grounded don t worry the next step will take care of that 5 Connect the channel 1 probe tip to point A and its ground clip to point C now point C is definitely grounded The output of the function generator displays as a waveform on channel 1 6 Press the MEASURE front panel button and set the function generator to provide a six volt peak to peak sine wave at 1 KHz If your function generator has an output level meter you may notice a discrepancy between its reading and the one on the oscilloscope Believe the oscilloscope the meter on the function generator is likely only accurate if its load is matched to its output impedance usually 50 or 600 ohms and this is not the case here 7 Connect the channel 2 probe tip to point B and its ground clip to point C 8 Use the VOLTS DIV front panel knob to adjust the amplitude of the displayed waveform and the POSITION knob to get a good view of the waveform 9 Use the Source and Type functions of the Measure menu to add a peak to peak voltage reading on channel 2 retain the peak t
17. orm The Ground Point You must always be aware that your voltage measurements are relative to ground potential when using the TDS 210 or TDS 200 oscilloscopes This ground is identical to the safety ground third pin of the power socket that the oscilloscope is plugged into For safety the shell of the BNC connectors are also connected to this ground as are the ground clips of the probes Most multimeters are battery powered This means that they are completely isolated from ground and that the meter leads are NOT grounded Therefore you can connect your multimeter to any point in a circuit without worrying about introducing an unwanted ground connection This is not true for oscilloscopes For the TDS 210 and TDS 220 oscilloscopes if the circuit under test has a ground point which it may not have if it operates from a battery or runs on a floating power supply then the oscilloscope ground must be connected to the same ground point CAUTION If you connect the oscilloscope ground to any other point of the circuit you will short out any components that are between this point and the circuit ground Using the Math Menu How do we see the waveform and measure the voltage between two points that are not both connected to the ground potential We use the Math menu To use the Math menu to measure voltages that are not both connected to the ground potential follow these steps 1 Connect a probe to the CH1 BNC connector and another pr
18. ou are measuring Using the Display Menu To understand various functions of the Display menu follow these steps 1 Press the DISPLAY front panel button The top menu item is Type which switches between dots and vectors and with this particular set of waveforms you will not see a noticeable difference When displaying ELEC 290 Lab Manual E3 15 Fall Term square waves or other waveforms that have rapid vertical excursions the vectors setting draws in the vertical lines to make the waveform easier to recognize 2 Press the Format bezel button and sekct XY You should see an ellipse on the screen we are now displaying channel as the X axis versus channel 2 on the Y axis 3 To make the ellipse more solid go back to the Persist bezel button and set it to 2 Sec Note that the ellipse fills in because the oscilloscope is now keeping two seconds of history on the screen The bottom two buttons are labelled Contrast Increase and Contrast Decrease but they actually lower and raise respectively the screen brightness If the screen is too dark you actually need to press the Contrast Decrease button to raise the contrast A Note in Closing These four lessons by no means cover all the features of this oscilloscope nor the many kinds of measurement that you can make with it I hope however that they will get you up to the point where the oscilloscope is less intimidating and the official Tektronix manuals are easier to understand
19. reen because AUTOSET has set the oscilloscope s trigger to channel 1 and the trigger circuit causes successive similar waveforms to be superimposed on the screen For a complete discussion of trigger see the Tektronix manual If the top and bottom of the square waves are not straight your probe needs to be compensated but you do not need to do it right now ELEC 290 Lab Manual E3 3 Fall Term Tek mi Trig d M Pos 000s MEASURE TirihooTs Serer Mo are ee OC Ser Source CH1 i i l U APE PETET ETE TE 5 404 CH1 1 000kHz CH2 None 3 eee eee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee LLLE TI LE 5 3 F 233 CHT 3 00V CH2 S00mY MM 500us CHI J 2 34 To demonstrate the downside of using Autoset follow these steps a Disconnect the channel probe from PROBE COMP and connect channel 2 instead Press AUTOSET The wave is no longer stationary because there is no signal on channel to trigger the oscilloscope which is now free running b Press the TRIGGER MENU button near the right edge of the scope The third menu item is the trigger source which is currently set to CH1 c Press the button beside this menu item once to switch the source to CH2 The display should become stable d Now press AUTOSET again Once again the scope is free running because Autoset sets the trigger source to the lowest displayed channel This is just one of many setti
20. rent scales the result was not interpreted as a voltage 5 Turn the channel 2 VOLTS DIV knob one click to the left The vertical sensitivity on channel 2 should now match the vertical sensitivity on channel 1 1 volt per division You should see that the cursor and delta readings now have a V rather than a U after the number you now are reading a voltage This technique can be used any time that you need to see and measure a waveform somewhere in the middle of a circuit where neither end point is at ground potential ELEC 290 Lab Manual E3 12 Fall Term Lesson Four Time Measurements and the Save Recall Menu In this lesson you will learn about the following topics e How to save reference waveforms e How to use the Cursor menu to measure time For this lesson we need two waveforms that are separated in time The easiest way to do this is to use an RC resistor capacitor circuit If you have not yet studied the behaviour of capacitors just treat this as magic for now To setup the test circuit follow these steps 1 Build the following RC circuit B To do this replace the 10 KQ resistor in the Function Generator 20 KO previous circuit with a 0 33 WF capacitor this exact value is not required anything c in the general range will do 2 Set the function generator to output a sine wave at 50 Hz with a magnitude of 6 volts peak to peak 3 Connect the probe tip of channel 1 to point A the p
21. robe tip of channel 2 to point B and both ground clips to point C The capacitor causes a phase shift between the voltage and current in the circuit again if the RC circuit theory is not familiar to you don t worry about it so that the waveform at point A lags behind the waveform at point B as you can see on the oscilloscope display 4 Turn the Horizontal SEC DIV knob to set the time base to 5 ms per division read this at the centre bottom of the screen and adjust the settings to get a display similar to the next drawing Using the Save Recall Menu The Save Recall menu allows you to save all the control settings for the oscilloscope which is also called the setup Saving a setup is handy if you are doing a long experiment or repeated measurements and want to quickly re establish your configuration for your next session especially if the oscilloscope has been used for something else in between This menu also allows you to save two waveforms as references for use at a later time ELEC 290 Lab Manual E3 13 Fall Term To save a waveform follow these steps 1 Press the SAVE RCL front panel button The Save Recall menu appears 2 Press the top button to select Waveforms be sure that the Source menu item is set to CH1 and the Ref menu item is set to A 3 Press the button next to the Save menu item this saves the channel 1 waveform as reference A 4 Set the last menu item Ref A to Off The next drawing shows how the oscil
22. sive presses of the button rotate through 1X 10X 100X and 1000X As you press this button watch the ELEC 290 Lab Manual E3 7 Fall Term bottom left corner of the display the number that is changing is the volts per division If the readings seem wildly high or low when taking voltage measurements check that the Probe menu setting matches the probe connected between the oscilloscope and the circuit If you are using a straight coax cable connection set the Probe menu to 1X 8 Press the MEASURE front panel button We will now discover one of the most important things to remember when using the oscilloscope to take measurements from signals displayed as waveforms To do this we need to understand how the oscilloscope displays signals Notice that there is a small arrow at the top of the display and another at the right side both pointing inwards The one at the top shows the time of the trigger event and the one at the right shows the trigger voltage Because this is a storage oscilloscope it can display the waveform before the trigger event and the default horizontal position for the trigger is the centre of the screen If the arrow at the top of the display the trigger time is not at the centre use the Horizontal POSITION knob to move it to the centre Read the mean voltage The value should be approximately half the peak voltage it may actually be a bit less because the peak voltage includes any overshoot something to reme
23. steps 1 Press the CURSOR front panel button 2 Press the Type bezel button and select Voltage Two horizontal lines appear on the screen the voltage cursors The three bottom menu items show the cursor positions and the voltage difference between them Look beneath the Vertical POSITION knobs and you will see another set of labels CURSOR 1 and CURSOR 2 When you use the Cursor menu these knobs adjust the cursor positions The second menu item is for the cursor Source which is extremely important if you do not set this correctly you can get totally wrong results without realizing it The Source must be set to the waveform that you want to measure 3 Press the Source bezel button and select MATH 4 Use the CURSOR 1 and CURSOR 2 POSITION knobs to place Cursor 1 to the top of the Math waveform and the Cursor 2 to the bottom Tek JL Stop M Pos 0 000s curnsoR _ This shows how the oscilloscope ae ee ee ee ee ee ee display might look Source Look at the Delta menu item where i MATH you would expect to find the peak oe to peak voltage The value displayed 1 961 is followed by the letter U The U indicates that the value is unknown ST because the vertical sensitivity did SoS Ee not match on the waveforms used for cH Too CAE Shim MSs A AN This again demonstrates that the oscilloscope operates only on displayed waveforms Since the subtraction operation was performed on two displayed waveforms with diffe
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