Can you check if this is happening in the whole BTS, or only one cell, or only one TRX ?
I would assume a TRX is faulty, and swap it. Indeed, the TRX is the one in charge of encoding the voice, so a VQ problem is probably related to it.
Also, there is few radio mechanisms that could affect the VQ :
1. the DTX (discontinuous transmission). Try to disable this feature in this cell (DL DTX = off).
2. the TFO (if it is on, then turn it off, to test)
3. the AMR (perhaps ?) Try to turn that off too, if it was on.
But those features are usually activated on all the cells. So why would a feature not work in a particular cell ? Well, probably because the TRX is faulty…
So conclusion is still the same.
I can see the log file… if you do a screen shot of 3 consecutives measurements, showing the BER, FER, RXQUAL SUB & FULL, RXLEV SUB & FULL and SQI 🙂
You can upload those shots easily through photobucket.com. Just sen me the HTTP links.