Measurement Basics
R&S
®
FSW-K7
31User Manual 1173.9240.02 ─ 17
Demod. band-
width
Sample rate Measurement time Trigger offset
Min. Max. Min. Max.
50 kHz 200 kHz 5 us 120 s -120 s 1048.575995 s
25 kHz 100 kHz 10 us 240 s -240 s 2097.15199 s
12.5 kHz 50 kHz 20 us 480 s -480 s 4194.30398 s
6.4 kHz 25.6 kHz 39.0625 us 937.5 s -937.5 s 8191.999961 s
3.2 kHz 12.8 kHz 78.125 us 1875 s -1875 s 16383.99992 s
1.6 kHz 6.4 kHz 156.25 us 3750 s -3750 s 32767.99984 s
800 Hz 3.2 kHz 312.5 us 7500 s -7500 s 65535.99969 s
400 Hz 1.6 kHz 625 us 15000 s -15000 s 131071.9994 s
200 Hz 800 Hz 1.25 ms 30000 s -30000 s 262143.9988 s
100 Hz 400 Hz 2.5 ms 60000 s -60000 s 524287.9975 s
* Gaussian filter curve is limited by I/Q bandwidth
2)
only available with option B40
4)
only available with option B160 or higher
5)
only available with option B320 (not B500)
Large numbers of samples
Principally, the R&S FSW can handle up to 1.6 million samples. However, when 480
001 samples are exceeded, all traces that are not currently being displayed in a win-
dow are deactivated to improve performance. The traces can only be activated again
when the samples are reduced.
Effects of measurement time on the stability of measurement results
Despite amplitude and frequency modulation, the display of carrier power and carrier
frequency offset is stable.
This is achieved by a digital filter which sufficiently suppresses the modulation, provi-
ded, however, that the measurement time is ≥ 3 x 1 / modulation frequency, i.e. that at
least three periods of the AF signal are recorded.
The mean carrier power for calculating the AM is also calculated with a digital filter that
returns stable results after a measurement time of ≥ 3 x 1 / modulation frequency, i.e.
at least three cycles of the AF signal must be recorded before a stable AM can be
shown.
4.4 AF Triggers
The Analog Demodulation option allows triggering to the demodulated signal. The dis-
play is stable if a minimum of five modulation periods are within the recording time.
AF Triggers
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