R&S FSW Series, Руководство пользователя

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Measurements and Results
R&S
®
FSW
305 User Manual 1173.9411.02 ─ 43
t5: End of burst (after 602 µs)
The instrument has to be configured as follows:
Trigger Offset t2 – t1 = 25 µs now the gate ranges are relative to t2
Range1 Start t3 – t2 = 15 µs start of range 1 relative to t2
Range1 End t4 – t2 = 553 µs end of range 1 relative to t2
7.8.7.2 Measurement Example – Measuring the APD and CCDF of White Noise Gener-
ated by the R&S
FSW
Setting the analysis bandwidth
When the amplitude distribution is measured, the analysis bandwidth must be set so
that the complete spectrum of the signal to be measured falls within the bandwidth.
This is the only way of ensuring that all the amplitudes will pass through the IF filter
without being distorted. If the selected bandwidth is too small for a digitally modulated
signal, the amplitude distribution at the output of the IF filter becomes a Gaussian dis-
tribution according to the central limit theorem and thus corresponds to a white noise
signal. The true amplitude distribution of the signal therefore cannot be determined.
A programming example demonstrating a statistics measurement in a remote environ-
ment is provided in
Chapter 14.5.9.7, "Programming Example: Measuring Statistics" ,
on page 975.
1. Preset the R&S FSW.
2. Set the reference level to -60 dBm .
The R&S FSW's intrinsic noise is displayed at the top of the screen.
3. Select the "APD" measurement function from the "Select Measurement" dialog
box.
The R&S FSW sets the frequency span to 0 Hz and measures the amplitude prob-
ability distribution (APD). The number of uncorrelated level measurements used for
the measurement is 100000. The mean power and the peak power are displayed in
dBm. The crest factor (peak power – mean power) is output as well.
Statistical Measurements (APD, CCDF)