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EXPERIMENT 3

DIGITAL STORAGE OSCILLOPSCOPE

3.1 Objective:

In this experiment, you will learn the basic usage of digital storage oscilloscope (DSO) ofAgilent Technologies. More specifically you will learn,

1. How to determine the amplitude and frequency of a signal using DSO,2. How to make some mathematical operations on signals using DSO,3. Identifying the phase difference between the output and input signals in capacitor

and inductor circuits using DSO,4. X-Y mode of operation in digital oscilloscopes.

3.2 Equipment List:

- Digital Storage Oscilloscope (AgilentDSO3062A)

- Function/Arbitrary Waveform Generator (Agilent33220A)

- CADET or Breadboard- Carbon Resistors (1 k, 1.5 k, 3.3 k),

- Capacitor (47 nF),

- Inductor (0.1 H).

3.3 Preliminary Work:

- Read the sections Measurement Techniques and Controls in Notes onOscilloscopes.

1. What is DSO? What are the differences between CRO and DSO?

2. What is phase difference?

3. What does the terms leading and lagging mean?4. Explain the measurement techniques of phase difference. Is there any ambiguity

related to these techniques?

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Fig 3.1

3.4 Experimental Work:

- The front panel ofAgilentDSO3062A oscilloscope is shown in Fig. 3.1. You mayrefer to this figure during the experiment.

1. Turn the oscilloscope on. Connect the signal lead of the probe corresponding to

Channel 1 to the Probe Comp output of the oscilloscope. Press the Autoscale key.

(Wait a few seconds until the oscilloscope completes the operation.) At this instantyou observe a square wave signal generated by the oscilloscope. Observe the

reference point shown by ( ) sign in the left side of the display which

corresponds to the ground level of the waveform. Measure the peak-to-peakamplitude and the period of the signal by counting the squares in the display. Record

these values.

a. Play with the Vertical Division Control of the Channel 1 and observe the

changes in the waveform. What is happening?

b. Play with the Horizontal Division Control of the oscilloscope and observethe variations in the display. What is happening?

c. Play with the Vertical Position Control and observe the changes in the

display.

d. Play with the Horizontal Position Control and observe the changes in the

display.

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2. Press Channel 1 selection button. Be sure that Channel 1 is active. If not, pressChannel 1 selection button again. At this instant you should be observing a menu inthe right side of the display.

a. From that menu, press to the soft key corresponding to Coupling to change

the coupling mode from DC mode to GND mode. Observe the changes in the

waveform. Press again to the same softkey to make the coupling mode to ACmode. Plot the resulting waveform observe the changes.

b. Return to the DC coupling mode by selecting the DC mode from the

Coupling submenu. Plot the waveform. Now press the Invert soft key from

the menu. Plot the resulting waveform and observe the change in the waveform.

3. Press the Channel 1 selection button to make the channel inactive. Then disconnect

the Channel 1 probe from Probe Comp output and connect Channel 2 probe to the

same place. Press the Channel 2 selection button and repeat steps 1 and 2 for Channel

2 without adding the results to your report.

4. Cancel the Invert mode operation of Channel 2 and observe the regularwaveform on the display.

a. Press the Cursors button. A Cursors menu will appear in the right side ofthe display. Press the Source softkey to make the source CH 2. Press the

Type softkey to make the type Voltage. Then, select the cursor A by pressing

to the CurA softkey. Change the position of the cursor A by playing with theEntry Knob. Similarly, press the soft key corresponding to cursor B and change

the position of the cursor B by playing with the Entry Knob.

b. Now using the cursors measure the peak to peak amplitude of the waveform

and record this value.

c. Change the cursor type from Voltage to Time by pressing the Type.Repeat the same operations for the vertical cursors by measuring the period and

frequency of the waveform and record these values.

5. Press Measure button. A menu will appear in the right side of the display. (Whenmenu in the right side of the display disappears, you can press the Measure button

or Menu ON/OFF button again.)

a. Press that softkey corresponding to Voltage from the menu. Now, measure

the peak to peak voltage of the waveform by pressing the softkey correspondingto V

pp

. Record this value.

b. Press the softkey corresponding to Time from the menu. Now, measure theperiod of the signal by pressing the period softkey corresponding to Period.

Record this value. You can also measure the frequency, rise time, fall time etc. by

pressing the corresponding softkeys from the menu.

c. Use the Clear softkey to clear all of the existing measurements on the display.

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6. Turn theAgilentfunction generator on. Set theAgilentfunction generator to HighZ mode. For this purpose, press the Utility key in the front panel of the Agilentfunction generator. From the menu, choose the Output Setup option. Then, choose

the High Z option from the appearing menu. Press DONE. Set up the circuit of

Fig 3.2. Enable the output of theAgilentfunction generator by pressing the Output

button.

(R = 3.3 k, C = 47 nF)

a. Observe and plot Vin(t) and Vo(t) simultaneously. Determine the phase

difference using the cursors properly.

b. Set the oscilloscope to X-Y operation. For this purpose press Main-Delayed

button. From the menu, set Time-Base option to X-Y mode.Observe and plotthe figure on the screen. Determine the phase difference.

7. Repeat Part 6 for the circuit below with R = 3.3 k, L = 0.1 H.

8. Set the function generator to High Z mode as explained in part 6. Select the

sinusoidal waveform mode. Adjust the amplitude to 3 Vpp

and frequency to 1.003

kHz. Then connect the Channel 1 probe of the oscilloscope to the output of the

function generator. Deactivate and disconnect Channel 2. Then activate Channel 1.

Press the Autoscale button on the oscilloscope. At this instant, you will beobserving a sinusoidal signal on the display. Measure the amplitude and the

frequency of this signal with the help of Measure function. Record the values.

Fig. 3.3

Fig. 3.2

Vin(t) = 2sin(4000t)

Function/Arbitrary

Waveform Generator

(Agilent33220A)

Vin(t) = 2sin(4000t)

Function/Arbitrary

Waveform Generator

(Agilent33220A)

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9. Connect Channel 2 of the oscilloscope to Probe Comp output. Activate Channel2. Be sure that both Channel 1 and Channel 2 are activated. Then press Autoscale

button. At this instant you should be observing two waveforms simultaneously on the

screen. One of them should be sliding and the other should be steady.

a. Press the Mode/Coupling button on the front panel. Trigger menu appearsin the right side of the oscilloscope screen. Press the Source softkey to make the

source CH 1. Press Autoscale button. Now, the oscilloscope is generating the

trigger signal with respect to the signal in Channel 1. Which signal is steady?

b. Make the triggering source CH 2 by pressing the Source softkey again.Which signal is steady? (You may need to adjust the triggering level by using the

Level knob for proper triggering.)

c. Make small variations in the frequency of the output signal of the function

generator until you observe two slightly steady waveforms on the oscilloscopescreen. In order to achieve this, the frequencies of the two signals in Channel 1

and Channel 2 should be very close to each other. Record this value.10. Set up the circuit in Fig. 3.4. Connect Channel 1 and Channel 2 of the

oscilloscope as shown in the figure. Then, press Math button. A menu will appearin the right side of the oscilloscope screen. You will also observe a third signal (the

purple one) on the oscilloscope screen.

a. Press the soft key corresponding to Operate to make the operation A-B.

This operation subtracts the signal in Channel 2 from the signal in Channel 1 and

the third signal you observed corresponds to the difference signal. You can alsoadjust the reference point and scale of the resulting signal. For this purpose, you

can use the softkeys from the second part of the Math menu. Plot the third

signal.

b. Press the soft key corresponding to Operate repeatedly to select the operationA+B. Observe the sum of the two signals in Channel 1 and 2 on the display.

Plot the resulting waveform.

Vin(t) = 2sin(4000t)

Function/Arbitrary

Waveform Generator

(Agilent33220A)