Specifications

Measurements R&S FSH
1145.5973.12 4.132 E-10
The Fig. above shows 30 measured values which are represented by a single pixel. The peak detector
determines and displays the maximum measured value. The Auto Peak detector takes the maximum
and minimum and displays them together. The two values are joined by a vertical line segment. This
gives a good indication of the level variation over the measured values represented by a single pixel.
The RMS detector is used by the spectrum analyzer to determine the RMS value of the measured
values. It is therefore a measure of the spectral power represented by a pixel. The sample detector
takes an arbitrary measurement value and displays it (in the Fig. above, the first). The other measured
values are ignored.
On the basis of the operating principles of detectors, a few recommendations can be made as to their
use.
• It is best to use the Auto Peak detector or the peak detector for spectrum analysis over large
frequency ranges. This ensures that all signals are displayed.
• The RMS detector is recommended for power measurements on modulated signals. However, the
display range should be chosen so as not to exceed 100 times the bandwidth of the signal or the
resolution bandwidth, whichever is larger.
• The sample detector or the RMS detector (preferred) should be used for noise measurements. Only
these two detectors are capable of measuring noise power correctly.
• When measurements are made on sine signals, the level display does not depend on the detector.
However, if you use the RMS detector or the sample detector, ensure that the span is not too great.
Otherwise, the displayed levels of sine signals may be lower than their true value.