Spectrum Analyzer Mode
R&S
®
Cable Rider ZPH
231
User Manual 1321.0950.02 ─ 07
3. Select the detector you want to use.
If the "Auto Detector" selection is active, the selection of the trace detector follows
Table 8-1
.
The R&S Cable Rider ZPH provides several types of detectors.
●
Auto Peak
If the auto peak detector is active, the R&S Cable Rider ZPH displays both the
maximum and the minimum power levels that were measured in the frequency
range covered by a pixel.
Therefore, the auto peak detector loses no information. If a signal power level fluc-
tuates (e.g. noise), the width of the trace depends on the magnitude of the signal
fluctuation. The auto peak detector is the default detector.
●
Max Peak
If the max peak detector is active, the R&S Cable Rider ZPH displays only the
maximum power levels that were measured in the frequency range covered by a
pixel.
The max peak detector is useful for measurements on pulse or FM signals, for
example.
●
Min Peak
If the max peak detector is active, the R&S Cable Rider ZPH displays only the mini-
mum power level that were measured in the frequency range covered by a pixel.
The min peak detector displays sine signals with the correct level and suppresses
noise. Therefore it is useful to find sine signals in the vicinity of noise.
●
Sample
If the sample detector is active, the R&S Cable Rider ZPH shows one random
power level that was measured in the frequency range covered by a pixel.
The sample detector is useful for measurements in the time domain (span = 0 Hz)
as it provides the only way to represent the timing of the video signal correctly.
In the frequency domain, the sample detector is a good way to measure noise
power because noise usually has a uniform spectrum with a normal amplitude dis-
tribution.
Signals may get lost if you are using the sample detector for measurements with a
span that is greater than "RBW * 711".
●
RMS
If the RMS detector is active, the R&S Cable Rider ZPH measures the spectral
power over one pixel. In case of power measurements, the RMS detector always
shows the true power of a signal, regardless of the shape of the signal.
The RMS detector is best for measurements on digitally modulated signals
because it provides stable and true power readings. In combination with a high
sweep time, you can increase the display stability even more because the mea-
surement time for each pixel increases.
Noise measurements also provide stable results if you apply the RMS detector in
combination with a high sweep time.
However, the bandwidth occupied by the signal to be measured should at least
equal the frequency covered by a trace pixel or the selected resolution bandwidth
(whichever is larger). Otherwise, the power the R&S Cable Rider ZPH shows is too
low because there are spectral components within the frequency range covered by
the pixel that do not originate from the signal you want to observe (e.g. noise).
Configuring Spectrum Measurements
