Exercise 3 – Basic instrumentation:
Electronic oscilloscope I
1.
Aim of the exercise
The aim of the exercise is to familiarize students with digital oscilloscope. In this exercise issues
will be presented which are mainly related to the signal observation and the measurement of
the voltage of electrical signals.
Main topics
 familiarize students with the basic functions of the oscilloscope,
 measurement of the voltage signals,
 usage of digital signal processing such as averaging.
2.
Gained skills
 the ability to correctly connect the oscilloscope to the circuit and obtain a stable
image in single-channel mode.
 the ability to use of basic functions of the vertical block of the oscilloscope
 the ability to measure voltage parameters of electrical signals.
3.
Instrumentation
Digital oscilloscope Rigol DS 1052E
Running status
Location of waveform
window in memory
Trigger point
in memory
Contekst menu
Signal in channel 1
Reference level
of CH1
Signal in channel 2
Reference level
of CH2
Channel coupling and
vertical div of CH1
Channel coupling and
vertical div of CH2
Horizontal time base div
Fig. 1. Display screen
Common
menu buttons
Vertical
control block
Trigger control
block
Horizontal
control block
Probe
compensation
output
Signal input
channels
Fig. 2. Front Panel of the oscilloscope

Voltage measurement accuracy
Manual mode
𝛿𝑔 𝑈 = 𝛿𝑔 𝐿 + 𝛿𝑔 𝐶𝑌
where:
𝛿𝑔 𝐿 =
0,1 𝑑𝑖𝑣
𝐿
(1)
∙ 100%
𝛿𝑔 𝐶𝑌 = 3%.
Cursors and automatic function mode
𝛿 𝐶
𝑔 𝑌
∆g 𝑈 = (100%
∙ 𝑈 + 0,1 dz ∙ 𝐶𝑌 + 1 𝑚𝑉)
𝛿𝑔 𝑈 = 𝛿𝑔 𝐶𝑌 +
0,1 dz∙CY +1𝑚𝑉
𝑈
∙ 100%
(2)
(3)
Signal generator Keysight 33511B
1
2
3
4
5
6
10
7
9
8
Fig. 3. Front panel of the signal generator
4.
Measurements and tasks
starting work, it is recommended to restore the factory settings of the oscilloscope. To
 Before
do this, use the following command sequence:
(MENU)  Storage  Waveform  Factory  Load.
Task 1. Observations of the electrical signals.
the signal generator output to the CH1 input of the oscilloscope. Among available
 Connect
generator’s arbitrary signals, select the signal called "test1" ( Waveform  Arb 
Arbs  Select Arb). Enable the generator’s output ( Channel  Output on/off). Make sure the
oscilloscope operates in AUTO trigger mode ((TRIGGER)  Menu  Sweep  AUTO).
Set the oscilloscope to obtain a stable signal trace on the screen. Put the oscillogram and
 1.1.
values of both horizontal and vertical scales (C , C ) into the report.
X
Y
Based on signal observation examine and comment on the impact of the AC, DC, GND
 1.2.
coupling type on the shape and position of the observed signal
(CH1  Coupling  AC/DC/GND).
Based on signal observations investigate the operation of the "POSITION" knob in the
 1.3.
VERTICAL section.
!
What happens to the position of the observed signal and GND level by changing the “POSITION”
knob?
Based on signal observations investigate the operation of the "POSITION" knob in the
 1.4.
HORIZONTAL section and the knob "LEVEL" in the TRIGGER section.
!
What is the difference in the operation of both knobs? Notice the position of the trigger point
on the oscilloscope screen.
!
What happens to the observed signal if TRIGGER LEVEL is outside the range of the signal
amplitude?
Task 2. Voltage measurements.
 Select the arbitrary waveform called “test2” on the function generator.
Take the measurement of the peak-peak voltage (Vpp) of the observed signal with the
 2.1.
manual procedure (length measurements)
!
To ensure the best accuracy of the measurements select the proper signal coupling type
(AC/DC) and vertical scale. Justify the choice of the coupling type.
 Insert the oscillogram into the report. Estimate the limiting error of the Vpp measurement.
Take measurement of Vpp value with use of the vertical cursors ((MENU)  Cursors
 2.2.
 MODE  Manual / TYPE  Y).
 Insert the oscillogram in the report. Estimate the limiting error of the Vpp measurement.
Take the measurement of Vpp and U values with the use of the automatic measurement
 2.3.
functions
0
(MENU)  Measure  Voltage  Vpp, Vavg:
- for DC coupling when whole signal and ground level are visible,
- for AC coupling, set oscilloscope to obtain maximum accuracy of measurement.
 Estimate the limiting error of the Vpp and U measurement.
0
!
Compare the measurement results obtained from the tested methods. What can
you say about the automatic measurements functions?
!
Do the automatic measurement functions work properly in the case where a part
of the observed signal is outside the screen of the oscilloscope?
Task 3. Measurements of noisy signals.

Select the arbitrary waveform called “test3” on the function generator. If observed signal is not
stable, set triggering on the SLOPE mode (TRIGGER)  Menu  Mode  Slope.

3.1. Take the measurement of Vpp value with the use of the vertical cursors
((MENU)  Cursors  MODE  Manual / TYPE  Y) and with the use of automatic
measurement functions. Try to reduce noise assuming that its distribution is symmetrical with
respect to measured signal.

Insert the oscillogram with cursors positions in the report and write down result of automatic
function.
!

!

Compare obtained results and comment if you can see any discrepancies.
3.2. To reduce the random noise, select Average Acquisition ((MENU)  Acquire
 Acquisition  Average). Set the averaging rate to 64.
Repeat measurements of Vpp with the use of cursors and automatic function.
Write down the results of both measurements.
Compare and comment the results obtained in point 3.1 and 3.2.
NOTE! After the measurements are done, deactivate averaging mode:
(MENU)  Acquire  Acquisition  Normal.
Task 4. Oscilloscope’s probe

Connect the probe to CH1 input of the oscilloscope. Set the probe attenuation to x10 and the
proper attenuation in the screen menu CH1  PROBE  10x.
Note: When the measurements with the probe are done, set the oscilloscope attenuation to
1x. CH1  PROBE  1x.
Probe
compensator
Fig. 4. Setting probe attenuation and compensation verification
Use the Probe compensator output (Fig. 4) verify if the probe is compensated. If necessary,
 4.1.
ask Supervisor for assistance to adjust the trimmer capacitor on the probe for the flattest
square wave possible as displayed on the oscilloscope.
Insert the oscillogram with the compensation signal in the report.

4.2. Select a square waveform on the Keysight generator (Waveform  square) and set the
frequency and the amplitude to around 200 kHz and 5 Vpp respectively. Connect a resistor of
8,2 kΩ to the generator to increase its output resistance.
Observe the output signal while it is supplied to the oscilloscope with coaxial cable and the
probe.
Insert both oscillograms into the report.
Comment any differences in signal shapes.
!
Does the probe eliminate distortions (shape and value) in the observed trace of the
signals coming from sources with the high output resistance?
5.
Control questions
1. Is it possible to observe any changes in the position of the rectangular signal trace when you
turn the trigger Level knob? Justify your answer.
2. What is the compensation of the oscilloscope’s probe?
3. What is the reason to apply the oscilloscope’s probe?
4. How to detect, by means of the oscilloscope, that the observed signal has a non-zero DC
component?
5. Oscilloscope is supplied with a sinusoidal signal having an amplitude of 2 V and the frequency
of 2 kHz. Sketch the signal trace on the screen if CY = 1V/div, and CX = 50 µs/div. Display of
the oscilloscope has dimensions of 8 x 10 div.
6. An oscilloscope displays signals’ traces shown in Fig. 5. What is the amplitude of the
sinusoidal signal if the vertical scale CY is equal to 2 V/div?
Fig. 5 An exemplary oscillograms displayed on the screen.
7. An oscilloscope displays signals’ traces shown in Fig. 5. What is the amplitude of the square
signal if the vertical scale CY is equal to 1 V/div?
8. Evaluate the limiting error of the amplitude measurement performed for the sinusoidal signal
shown in Fig. 5, if the peak-peak distance were read. Inaccuracy of the vertical scale is 30%.
9. Evaluate the limiting error of the amplitude measurement performed for the rectangular
signal shown in Fig. 5. Inaccuracy of the vertical scale is 30%.
10. What is the visible effect on the oscilloscope’s screen, when trigger level is out of the range
of the signal’s amplitude. Consider two cases: AUTO and NORM trigger mode.
11. What is the difference in the observed signal once you apply AC or DC signal coupling mode?
12. The probe is in compensation state. Will the probe be still compensated if you elongate the
probe’s cable with additional coaxial cable? Justify your answer.
13. How to measure, by means of the oscilloscope, a DC component of the following signal
u(t) = U0 + Umsin(ωt)? Select a proper signal coupling mode.
14. How to measure by means of the oscilloscope, an AC component of the following signal
u(t) = U0 + Umsin(ωt) in the most accurate way? Select a proper signal coupling mode.