R&S FSMR, Operating Manual

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Analyzer - Bandwidths and Sweep Time R&S FSMR
1166.3363.12 4.8-8 E-1
Sweep time Defined by the selected bandwidth and span
(reason: FFT filtering is a block transformation).
It cannot be changed (softkey deactivated).
Detector Sample detector and peak detector are
available. Peak detector is active when AUTO
SELECT is selected.
Video bandwidth Not defined in case of FFT; therefore cannot be
set (softkeys deactivated).
Compared to bandpasses, FFT filters lead to significantly reduced
sweep times. For a span of 50 kHz and a bandwidth of 100 Hz, for
instance, the sweep time is reduced from 5 s to 40 ms. FFT filters are
particularly suitable for stationary signals (sinusoidal signals or signals
that are continuously modulated in time). For burst signals (TDMA) or
pulsed signals, normal filters are preferable.
As soon as the FFT filters are active (RBW 30 kHz) the sweep time display field (SWT)
is replaced by the acquisition time (AQT) display field.
FFT is a block transformation so the result depends on the time relation between the data
set to be transformed and the burst or pulsed signal. A gated sweep measurement for
TDMA signals is therefore not provided if FFT filters are used.
Additionally, a number of especially steep-edged channel filters are available for
power measurement since firmware version 1.10.
A distinction is made between the following filter types:
CHANNEL =
general, steep-edged channel filters
RRC = filters with root-raised cosine characteristic
(RRC = Root Raised Cosine)
When selecting these filter types, the automatic coupling of the resolution
bandwidth to the span is not available. The filters are selected via the
RES BW
softkey.
A list of all available channel filters with their associated applications can be found
at the end of this chapter.
IEC/IEEE-bus command:
SENS:BAND:TYPE NORM | FFT | CFIL | RRC