There is a correlation between FER and BER, which is empirical. It is noted that :
with No Hopping, an acceptable voice quality (FER) occurs when RXQUAL is below 4 (BER).
With Hopping, acceptable VQ occurs when RXQUAL below 5.
The SQI is between 0 and 30, or something like this. It is well explained in the TEMS user guide.
30 is very good, and 0 is really poor 🙂