Spectrum Analyzer Mode
R&S
®
Spectrum Rider FPH
192
User Manual 1321.1011.02 ─ 11
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Min Peak
If the max peak detector is active, the R&S Spectrum Rider 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.
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Sample
If the sample detector is active, the R&S Spectrum Rider 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".
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RMS
If the RMS detector is active, the R&S Spectrum Rider 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 Spectrum Rider 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).
To get the true power, the video bandwidth (VBW) should also be greater than the
resolution bandwidth (RBW). Otherwise, an averaging effect caused by video
bandlimiting comes into play before the RMS value is calculated.
The R&S Spectrum Rider provides automatic selection of the detector. In that case, the
R&S Spectrum Rider selects the detector that is most suitable for the current trace
mode.
Table 6-1: Auto selection of trace detector
Trace mode
Detector
"Clear/Write"
"Auto Peak"
"Average"
"Sample"
"Max Hold"
"Max Peak"
"Min Hold"
"Min Peak"
If you select the detector manually, the detector is independent of the trace mode.
Configuring Spectrum Measurements
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