Regarding to oc192 CDR jitter tolerance test and BERT:

When doing jitter tolerance test, sinusoidal jitter amplitude is modulated into input random data like PRBS7 or PRBS31 across different frequency. It obtains the max jitter tolerance amplitude until 1 bit error detected.  

How about BERT test? Is BERT without any jitter source? It needs to achieve BER 10^-12.