R&S FSMR, Operating Manual, Page: 247 / 955

R&S FSMR Analyzer - Traces
1166.3363.12 4.11-9 E-2
Sample detector
The SAMPLE detector routes through the sampled data without any
further evaluation and either displays them directly or, for reasons of
speed in case of short sweep times, first writes them into a memory and
processes them subsequently.
There is no data reduction, ie no summing up of measured values of
neighbouring frequencies or time samples. If during a frequency sweep
more measured values are obtained than can be displayed, measured
values will be lost. This means that discrete signals might be lost.
The sample detector therefore can only be recommended for a span-to-
resolution bandwidth ratio of up to approx. 250 in order to ensure that no
signal will be suppressed (example: span 1 MHz, -> min. bandwidth 5 kHz).
RMS detector
The RMS detector forms the rms value of the measured values within a
pixel.
To this effect, R&S FSMR uses the linear voltage after envelope detection.
The sampled linear values are squared, summed and the sum is divided by
the number of samples (= root mean square). For logarithmic display the
logarithm is formed from the square sum. For linear display the root mean
square value is displayed. Each pixel thus corresponds to the power of the
measured values summed up in the pixel.
The rms detector supplies the power of the signal irrespective of the
waveform (CW carrier, modulated carrier, white noise or impulsive
signal). Correction factors as needed for other detectors for measuring
the power of the different signal classes are not required.
Average detector
The average detector forms the average value of the measured values
within a pixel.
To this effect, R&S FSMR uses the linear voltage after envelope detection.
The sampled linear values are summed up and the sum is divided by the
number of samples (= linear average value). For logarithmic display the
logarithm is formed from the average value. For linear display the average
value is displayed. Each pixel thus corresponds to the average of the
measured values summed up in the pixel.
The average detector supplies the average value of the signal
irrespective of the waveform (CW carrier, modulated carrier, white
noise or impulsive signal).
Quasipeak detector
The quasipeak detector similates the behaviour of an analog voltmeter
by evaluating the measured values in a pixel.
The quasipeak detector is especially designed for the requirements of
EMC measurements and is used for evaluating pulse-shaped spurious.
During a frequency sweep, R&S FSMR increments the 1st local oscillator in steps that are
smaller than approximately 1/10 of the bandwidth. This is to ensure that the signal level is
correctly measured. For narrow bandwidths and wide frequency spans a very large
number of measured values is thus obtained. The number of frequency steps, however,
always is a multiple of 625 (= number of pixels that can be displayed). With the sample
detector selected, only every nth value is displayed. The value of n depends on the
number of measured values, ie on the frequency span, the resolution bandwidth and the
measurement rate.