Tektronix RSA2200A, User Manual

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Modulation Analysis (Demod Mode)
3- 36
RSA2203A & RSA2208A User Manual
Demodulates and measures an AM signal. Figure 3--33 shows an example. The
main view displays the measurement results and the modulation factor versus
time graph. MEASURE
→
Show Measurements is selected in Figure 3--33.
The modulation factor is defined by the following equation:
(modulation factor) = (A
m
-- A
0
) / A
0
Where
A
m:
Amplitude of the modulation signal
A
0
: Amplitude of the carrier with no modulation (0% modulation)
Meas Setup Menu. The Meas Setup menu for the AM demod measurement
contains the following control:
Carrier Amplitude Detection.
Selects how to calculate the amplitude of the
carrier with no modulation (A
0
in the above equation).
H
Average.
Default . Defines A
0
as the average amplitude in the analysis range.
H
Median.
Defines A
0
as the median amplitude ([(m(minimum)]/2)
in the analysis range.
Main view
Measurement results
From the top:
G
Positive peak AM value
G
Negative peak AM value
G
Total AM value
= (peak-peak AM value) / 2
Overview: Power versus Time Subview: Spectrum
Modulation factor variation
Figure 3- 33: AM demod measurement
AM Demod Measurement