thanks a lot for bringing this old thread back to life !
I understand the total of bits if different in SDCCH and in TCH timeslots. But the numerator (number of bits with error) is also different.
The ratio should remain similar between TCH and SDCCH.
for example, under the same radio conditions:
on a TCH timeslot : 100 bits with error over 10,000 bits -> BER = 1%
on a sdcch timeslot : 14 bits error over 1350 bits –> BER = 1%
waiting for your answer, because i think you have more to say 🙂