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2-8 Detection Spectrum Analyzer
2-10 PN: 10580-00349 Rev. M Spectrum Analyzer MG
2-8 Detection
Several detection methods tailor the performance of the instrument to meet specific
measurement requirements. In general, several measurement points are calculated for each
display point. The various detection methods are different ways of dealing with how
measurement point data is shown at each display point. Refer to
“Units & Detection Menu”
on page 2-57 .
Peak:
This method causes the largest measurement point to be shown for each display
point, and ensures that a narrow peak is not missed.
RMS/Avg:
This method performs a root-mean-square calculation of all the
measurement points in each display point. This is particularly useful in displaying the
average value of noise or noise-like signals.
Negative:
This method causes the smallest measurement point to be shown for each
display point. It is especially useful in zero span, to see if the signal amplitude drops
briefly. The method is also useful when looking at modulated signals, to see if some
frequencies are not being used.
Sample:
This is the fastest detection method because for each display point, only one
frequency point is measured. Use this method when speed is of paramount importance
and the possibility of missing a narrow peak is not important.
Quasi-peak:
When this selection is made, resolution bandwidths and video bandwidths
of 200 Hz, 9 kHz and 120 kHz are available. This detection method is designed to meet
CISPR requirements. (Not available in zero span.)
2-9 Indications of Excessive Signal Level
The Spectrum Analyzer has built-in features to indicate when a received signal is too high for
the current setup.
Figure 2-4 through Figure 2-8 illustrate a normal trace followed by
examples of screen messages indicating excessive signal levels. Before proceeding with the
measurements, adjust the reference level and/or the attenuator level as instructed. Adjusting
the resolution bandwidth and frequency range may also help.