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R&S
®
FSV-K70
346
Operating Manual 1176.7578.02 ─ 09
In case of a very short pattern, i.e. a pattern length in the order of the inter-symbol
interference (ISI) duration, a number of issues can arise:
●
False positive
The I/Q pattern is found at positions where the transmitted symbols differ from the
pattern symbols.
Solution: Try one of the following:
–
Activate "Meas only if Pattern Symbols Correct".
–
Increase the "I/Q Correlation Threshold"
(see
●
False negative
The I/Q pattern search misses a position where transmitted symbols match the pat-
tern symbols.
Solution:
–
Decrease the "I/Q Correlation Threshold"
(see
In case of bursted signals the pattern search finds only the first occurrence of the
I/Q pattern within each burst. If a false positive occurs in this situation (cf. case 1.)
the use of "Meas only if pattern symbols correct" will not provide a satisfactory sol-
ution.
In this case do the following:
–
Increase the "I/Q Correlation Threshold".
–
Specify the expected position of the pattern within the burst by adjusting the
"Offset" parameter.
Message: Sync Prefers More Valid Symbols
Note:
Note that this message does not necessarily indicate a problem. Its purpose is to
inform you that you might have the opportunity to get a more stable demodulation
and/or better measurement results by improving your setup.
Synchronization in the R&S
FSV-K70 is performed in two stages: coarse synchroniza-
tion that precedes the reference signal generation and fine synchronization based on
the reference signal.
●
The coarse synchronization stage can work data-aided (i.e. based on a known pat-
tern) or non-data-aided (i.e. based on the unknown data symbols). The default is a
non-data-aided coarse synchronization. In the case that a pattern is part of signal,
the user can switch to data-aided synchronization.
●
The fine synchronization stage always works data-aided.
'Sync Prefers More Valid Symbols' indicates that one of the synchronization stages has
too few symbols to ensure that the synchronization is robust.
The message is given if
●
Coarse Synchronization = Non-Data-Aided (User Pattern for Sync = Off):
Estimation range shorter than 40 symbols
(see
●
Fine Synchronization:
Estimation range shorter than 10 symbols
(see
Solution:
●
If the signal contains a pattern, set "Coarse Synchronization: Pattern".
(see
Explanation of Error Messages
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