Phy folks,

I have a question regarding the SSC profile to which I cannot find an answer in the draft spec.  (As usual, my apologies if I’ve overlooked something.)  The question is how the profile is measured in practice. 

Measuring clock waveform periods will result in significant noise superimposed on the longer term frequency.  For example, 0.01UI instantaneous jitter in one clock cycle is a 10 000 ppm frequency error.  Obviously such data must be filtered, but what is the filter?  An obvious candidate is the low pass filter defined by 1-JTF, but this should probably be defined.

For what it’s worth, I do not believe there is even a defined measurement procedure to verify the +/-100 ppm “long-term” frequency tolerance.

Thanks for any pointers or opinions on this question.

Regards,

Mike