Question
Sometimes the synchronization between SME/IQ and FSE-B7/FSIQ in QPSK modulation does not work.
Synchronization between SME/IQ and FSE-B7/ FSIQ in QPSK Modulation
Answer
A reason for the error message SYNC NOT FOUND on the FSE/FSIQ screen in vector demodulation mode might be that the QPSK mapping in the generator (SMIQ or SME) and the analyzer (FSE+FSE-B7 or FSIQ) is different.
Possible solution: The SMIQ "QPSK ICO" mapping corresponds to the FSE "QPSK" mapping.
In the case of SMIQ QPSK mapping, the synchronization pattern 1001100000 (of SMIQ) has to be changed to 1101110000. Moreover, all other bits have to be remapped according to the following rule:
00-->00
01-->01
11-->10
10-->11