Instrument Functions for Vector Signal Analysis
R&S
®
FSV-K70
75
Operating Manual 1176.7578.02 ─ 09
When evaluating the capture buffer, the absolute frequency is derived from the mea-
sured phase, with T
D
=the duration of one sampling period at the sample rate defined
by the capture oversampling parameter (see
This measurement is mainly of interest when using the MSK or FSK modulation, but
can also be used for the PSK/QAM modulations. However, since these modulations
can have transitions through zero in the I/Q plane, in this case you might notice uncriti-
cal spikes. This is due to the fact that the phase of zero (or a complex value close to
zero) is of limited significance, but still influences the result of the instantaneous fre-
quency measurement.
Figure 3-5: Result display "Frequency Absolute" in normal mode
SCPI commands:
CALC:FEED 'XTIM:DDEM:MEAS'
to define the required source type (see
CALC:FORM FREQ
to define the result type (see
TRAC:DATA TRACE1
to query the trace results (see
3.1.1.6
Frequency Relative
The instantaneous frequency of the signal source.
The results are normalized to the symbol rate (PSK and QAM modulated signals), the
estimated FSK deviation (FSK modulated signals) or one quarter of the symbol rate
(MSK modulated signals).
t
MEAS
dt
d
t
FREQ
MEAS
2
1
Measurement Result Display
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