Support
R&S
®
FSV-K70
354
Operating Manual 1176.7578.02 ─ 09
In the R&S
FSV-K70, the Constellation I/Q diagram shows the de-rotated constellation
(i.e. for a
π
/4-DQPSK, 4 instead of 8 points are displayed). The inter-symbol interfer-
ence has been removed.
Note:
As of firmware version R&S
FSVA/FSV 1.70, a new result display ("I/Q Constel-
lation (Rotated)") is available that displays the rotated constellation, as the FSQ-K70
does.
For details on the Constellation I/Q diagram in the R&S
ter 3.1.1.11, "Constellation I/Q"
Table 6-1: Constellation I/Q and Vector I/Q for pi/4-DQPSK modulation
R&S FSQ-K70
R&S
FSV-K70
Problem: the MSK/FSK signal demodulates on the R&S FSQ-K70, but not on the
R&S FSV-K70 or: Why do I have to choose different transmit filters in the R&S
FSQ-K70 and the R&S FSV-K70?
When generating an MSK/FSK reference signal, the R&S FSQ-K70 automatically
replaces the Dirac pulses generated by the frequency mapper with square pulses with
the length of one symbol. In the R&S
FSV-K70, however, this "replacement" is part of
the transmit filter routine. Thus, the R&S FSQ and the R&S
FSV require different trans-
mit filters for measuring the same FSK/MSK signal.
Example:
●
If your transmit filter for the R&S
FSQ-K70 was "NONE", you need to choose "Rec-
tangular" as the transmit filter type in the R&S
FSV.
●
If your transmit filter for the R&S
FSQ-K70 was "GAUSS", you need to choose
"GMSK" as the transmit filter type in the R&S
FSV.
Problem: The EVM trace looks okay, but the EVM in the result summary is signif-
icantly different
Solution:
●
Make sure that the position of the "Evaluation Lines" is reasonable. The Result
Summary only evaluates sample instants that are within the evaluation lines.
Hence, in the case the "Result Range" covers the burst ramps, it is important to
adjust the "Evaluation Range" appropriately.
Frequently Asked Questions
Содержание FSV-K70
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