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EE 207 LABORATORY No. 10
SPECTRUM ANALYZER
Scope:
During this lab. you will:
 Use a spectrum analyzer
 Explore harmonic generation


Determine the harmonic
component of an output signal
Observe the change in harmonic
distortion between input and
output signals
Prelab:
Review section 15.3 and 15.4 of Dorf et al : Introduction to Electric Circuits
1.-Using the results of last lab. fill out the columns labeled “Computed values” table 10.1.
(Input Signal)
Use 1 V as the amplitude of the fundamental harmonic.
Order
Harm.
1
3
5
7
Table 10.1 (Input Signal)
Square Wave
Triangular Wave
Computed
Measured
Computed
Measured
Ampl.
Ratio
Ampl.
Ratio
Ampl.
Ratio
Ampl.
Ratio
Vn/V1
Vn/V1
Vn/V1
Vn/V1
1
1
1
1
1
2.- For the circuit shown in figure 10.1 determine the transfer function, (the output is the
signal (voltage), at point A) The fundamental frequency is 1 kHz. Use these results and
the results recorded under “computed values” in table 10.1 to determine the amplitude of
the output harmonics and fill out table 10.2 (“Calculated Values Columns”) Remember
that in the circuit model you have to include the internal resistance of the inductor.
Table 10.2 (Output signal)
Order
Harm
1
3
5
7
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Mag. of
trans.
funct.
Square Wave
Triangular Wave
Amplitude Output
Calculated Measured
Amplitude Output
Calculated Measured
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EE 207 LABORATORY No. 10
SPECTRUM ANALYZER
.
A
Figure 10.1
In-lab: Notice: It will be in room 612
3.- In the lab you will find the harmonic components of the input signal and the output
signal using a network analyzer and find the values needed to fill out the columns
measured values.
4.- Connect the function generator using a sinusoidal signal with a frequency of 1 kHz
(the frequency will remain constant) to the primary of a transformer (they were used in
experiment Nr. 3). Starting with an input amplitude of 1 V, increase the amplitude and
record the harmonics of the voltage recorded at the secondary terminals of the
transformer for various input voltages and fill out table 10.3.
Harm.
Table 10.3 Harmonic content of the secondary voltage of a transformer
Amplitude
1V
2V
3V
4V
5V
6V
7V
1
2
3
4
5
6
Tips for operation of the spectrum analyzer.
i.-Center the frequency Span knob of the spectrum analyzer to 25 kHz
ii.- Push the Set Ref buttom. The reference frequency will be set to 0 Hz. For each of the
harmonics you measure 1000 Hz will have to be added
iii.- Set the scale to Linear (You can experiment with the 10 dB/div scale) and the
Passband Shape to Hanning.
Report: Cut and paste this report in your lab note book. Fill out the tables before and
during the lab. Lab-books will be collected and graded.
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