Hi Rick, In my experience the 53132 is not good for ADEV measurements below 100s. It is just way too noisy. You can try longer measurement gate and averaging times, but theoretically the SD value should be similar for 100s or 1000s SD measurements if what you are measuring is actually the internal noise of the counter (this is what I suspect). You can capture the serial output of the 53132A and use Ulrich Bangerts' free Plotter utility to calculate SD and ADEV from that dataset. Very easy to do, but as I said not useful for anything but mediocre oscillators due to the high internal noise of that counter. One more tip: if you measure a 10MHz signal, then use a divide by 2 (flip flop etc) to get to 5MHz, and scale the measurement by 2x using the Math setting, this will give you one more significant digit on the 53132A due to a weird internal limitation of that counter. bye, Said In a message dated 9/7/2011 16:17:18 Pacific Daylight Time, [email protected] writes:
I was playing with an Agilent 53132 counter, and noticed that it measures "standard deviation" but doesn't seem to offer what everyone really wants, ie, Allan deviation. According to the textbooks, standard deviation won't work for oscillators because the mean is not fixed and the deviation goes to infinity. However, I tried it anyway on a high quality oscillator for 100 measurements of one second each (N=100) and it seemed to basically work, giving 2E-11 for the deviation. The drift over 100 seconds may be small enough that the mean didn't move significantly. I have a 53230 on order that does actually measure Allan deviation, but am trying to get some work done in the mean time with what I currently have. Can anyone comment on the relationship between the two types of measurements in the lab? (We know how they differ mathematically, but what is the practical implication). Rick _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
