Oscilloscope Measurement Labs
Contents
1. Oscilloscope Measurement Labs Triggering the Signal Edge and Pulse Width Triggering This lab exercise teaches general oscilloscope triggering and how to use edge triggering and pulse width triggering especially on a T DS2000 or TBS1000 Series oscilloscope Objectives At the end of this laboratory session you will be able to Understand the basics of trigger systems functions Use edge trigger to capture a signal with rising or falling voltage Capture a signal when pulse width or specified value Capture a signal when pulse width gt or lt specified value Equipment To carry out this experiment you will need Arbitrary Function Generator Tektronix AFG3022 or equivalent signal generator Oscilloscope Tektronix TBS1022 TDS2002 or equivalent 50Q BNC cable 50Q BNC feed through terminator optional Theory To perform this experiment you should be familiar with Oscilloscope user manual vertical system and amplitude measurement XYZs of Oscilloscopes Page 27 section Trigger System and Controls XYZs of Oscilloscopes Page 29 section Trigger Position XYZs of Oscilloscopes Page 29 section Trigger Sources XYZs of Oscilloscopes Page 30 section Trigger Modes Tektronix 1 Lab Exercise Oscilloscope Measurement Labs Triggering Key Concepts Triggering is the process of capturing a waveform based on various criteria you specify The trigger makes repetit2. oscilloscope that captures 10 horizontal divisions and a signal is acquired with horizontal resolution of 50uS div what is the total duration of the acquired waveform a 500 uS b 50uS c 5us d 0 500 uS 4 A sinusoid is acquired with a horizontal scale resolution of 1mS div What would the frequency of this sine wave be if 3 cycles occupy 2 4 horizontal divisions a 125 Hz b 1250 Hz c 416 7 Hz d 1kHz 3 Lab Exercise Oscilloscope Measurement Labs Triggering Experiment Setup Connect the AFG Signal Generator to AC power Step 1 Turn ON the AFG DUT Setup Set the signal type frequency and amplitude on AFG as per experiment requirements Enable the output on AFG channel Step 2 1 Power ON the oscilloscope Step 2 2 Make the connection between Signal Generator AFG and oscilloscope as shown in the below picture Step 2 Measurement Setup Step 2 3 Output of the AFG Signal Generator is connected to Channel 1 of the oscilloscope Step 2 4 Press Autoset on the scope to display the signal generated by AFG Note A 2 Vp p setting on most signal generators will produce 4 Vp p into the 1 MQ inputs on most oscilloscopes This is because most signal generators are calibrated assuming a 50Q load It won t affect the outcome of the lab If you want the settings to match you can add a 50Q feed through terminator to the input of the oscilloscope Alternatively the AFG3022 has a setting in
3. the Output menu called Load Impedance that allows you to specify a High Z high impedance load 4 Lab Exercise Oscilloscope Measurement Labs Triggering Lab Exercise Edge Triggering For the given signal 1 To understand the basics of trigger systems functions 2 To use edge trigger for capturing a signal when amplitude rises above fall below a defined amplitude Procedure Algorithm Power ON the signal generator AFG amp scope Make connection between AFG and scope with BNC cable Do AUTOSET on scope to capture and view the signal Go to trigger menu set the trigger type as edge and source as channel 1 set slope as Rising Falling When the trigger condition is satisfied the signal will be displayed on the screen AFG Signal Generator Setting Channel 1 Channel 2 gt Signal Type Square wave gt Amplitude 2 Vp p gt Frequency 1 kHz 5 Lab Exercise Oscilloscope Measurement Labs Triggering Observations Execution We observe that n trigger setup if we select Edge triggering as trigger Type and if we select rising edge as Slope then the signal trigger point will be on the Rising edge of the waveform f we select Falling edge as Slope then the signal will be captured with the trigger on the falling edge Screenshots M Pos 0000S TRIGGER Type SOuUrCE CH1 slope I H arliiriprrrrrirrrerpPeurrrrrrriegerrrrirrrrprutrrrirrebtreiegpretes d q i l
4. 2 c Pulse width is equal to specified value d Pulse width is not equal to specified value With this experiment we learned How to use the trigger function to trigger a signal when the pulse width of the signal is less than greater than and equal to a specified pulse width In real life applications we can use this concept To look for pulses those are narrower than the normal glitches on microcontroller data and control lines To trigger on pulse width modulation PWM waveforms 9 Lab Exercise Oscilloscope Measurement Labs Triggering Post Lab Assessment Answer the following List the concepts you have learned doing this exercise Copyright 2013 Tektronix All rights reserved Tektronix products are covered by U S and foreign patents issued and pending Information in this publication supersedes that in all previously published material Specification and price change privileges reserved TEKTRONIX and TEK are registered trademarks of Tektronix Inc All other trade names referenced are the service marks trademarks or registered trademarks of their respective companies 04 2013 48W 29161 1 10 Lab Exercise
5. G and scope with BNC cable Do AUTOSET on scope to capture and view the signal Go to trigger menu set the trigger type as pulse and source as channel 1 Set the pulse width When the trigger condition is satisfied the signal will be displayed on the screen AFG Signal Generator Setting Channel 1 Channel 2 gt Signal Type Square wave gt Amplitude 2 volt pk pk gt Frequency 1 kHz 8 Lab Exercise Oscilloscope Measurement Labs Triggering Observations Execution We observe that gt If we select Pulse Triggering as trigger type and if we select 1 gt as when to trigger then signal will trigger when the pulse width is greater than specified 2 lt as when to trigger then signal will trigger when the pulse width is less than specified 3 as when to trigger then signal will trigger when the pulse width is equal to within 5 specified 4 as when to trigger then signal will trigger when the pulse width is not equal not within 5 to specified Screenshots Trig d Trig d gt A eee ce ces ae fie eee ie Pulse Width Pulse Width 1 00ms 5 l 7 1 00ms CH1 1 0 CH1 JL 0 00 CH1 1 0 CH1 JL 0 00 430 001H2 300 003Hz a Pulse width is greater than specified value b Pulse width is less than specified value Trig d Auto Bc ee se Pulse Width Pulse Width 1 00ms 5 1 00ms CH1 1 0 CH1 JL 0 24 CH1 1 0 CH1 JL 0 24 480 001H
6. ive waveforms appear static on the oscilloscope display by capturing at the same point in the signal and repeatedly overwriting the signal with itself Types of Triggering You can use any channel Ch1 Ch2 Ext as a source for triggering You can only have one trigger at any given time Figure 1 Edge Triggering Edge Triggering Edge triggering is a process of triggering on the first occurrence of a rising or falling voltage You can set the trigger voltage level and choose rising of falling voltage Pulse Triggering Pulse triggering is a process of triggering on the first occurrence of a pulse with a specified pulse width You can choose to trigger when pulse width is greater than less than approximately equal to or not equal to a pulse width you specify You can also specify the polarity of the pulse you want to capture that is whether it is positive rises then falls or negative falls then rises 2 Lab Exercise Oscilloscope Measurement Labs Triggering Check Your Understanding Answer the following 1 Triggering is required Check all that apply a To make a signal appear clearly on the display b To display a specific part of a signal on the display c To make dynamic signal look static on the display d To acquire a signal with specific characteristics 2 Which of the following Trigger type is not present in TBS1000 or TDS2000 Series oscilloscope a Pulse width b Glitch c Edge d Video 3 Ifyou have an
7. s Mode Coupling MM 250 Te 12 Dec 12 11 54 TRIGGER Type SOuUrCE H1 slope Falling Mode Auto Coupling Mi 250 T 12 Dec 12 11 34 Falling edge trigger with pulse wave 6 Lab Exercise Oscilloscope Measurement Labs Triggering 7 Lab Exercise M Pos 0000s TRIGGER Type KOJCE CH1 slope Mode Coupling Mi 250 at 12 Dec 12 17 55 TRIGGER Type Coupling CH1 1 0 Mi 250 us Current screen display sawed to 4 4 TEK0OZ26 JPG Falling edge trigger with sine wave With this experiment we learned How to use the trigger function on the oscilloscope to trigger on the positive or negative edge of a signal In real life applications we can use this concept To analyze the seismic waves from the earth to for early detection of an earthquake To capture a stable waveform even with noisy irregular wave shape Oscilloscopes that are capable of advanced triggering are ideal for troubleshooting glitches timing violations overvoltage and dropouts in analogue and digital circuits Oscilloscope Measurement Labs Triggering Lab Exercise Pulse Width Triggering For the given signal 1 To understand the basics of trigger systems functions 2 To capture a signal when pulse width is or specified value 3 To capture a signal when pulse width is gt or lt specified value Procedure Algorithm Power ON the signal generator AFG amp scope Make connection between AF
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