#### poorren

##### Junior Member level 3

The question comes from evaluate two rubidium clock sources, one is bought as used clock with nice price, another is disassembled from an old basestation. I don't know the detailed spec of two clocks. After reading some material on time source measurement, I found the methods on the table (commerial counter TIC or dual mixer time difference method) require to use a more stable clock to measure another one. Because all the methods above are relative measurement, the confidence is based on priori knowledge on standard performance.

So, my curiosity drive me to ask how to compare two clock with unknow performance (short term jitter and long term stability)? I am not sure if my understanding is correct, we need to find a way to evaluate a clock

**WITHOUT**effect of another clock.

Thanks for your time to reply.

Jeff