Paul, as I said I just want to know how close my crystals are and be able to adjust them as well as they can be.
I probably will never go rubidium (note that I qualified that) but still somewhere one has to decide where to set the frequency. I did WWV at 20 MHz for a beat of somewhat slower than one per second. I know the phase changes but probably not much in a few minutes, as the path length doesn't vary very quickly. And I don't need phase lock to them anyway. In the old days they had 25 MHz and even 30 MHz for a slight improvement in settability if not stability. Bob On Saturday, March 1, 2014 7:38 PM, Hal Murray <[email protected]> wrote: > I am trying to understand how this is done. Should I ever get a rubidium > standard, I'd want to check its calibration, and that's not a trivial > exercise. If you assume your rubidium is stable, then it's pretty easy to check and/or calibrate. The trick is that you need someplace to stand. A PC running ntp is good long term. There is a tradeoff between good and long. Good is ambiguous, but both how-good is your PC clock and how good/accurate a measurement do you want are appropriate. Probably the simplest way is to get one of tvb's preprogrammed PICs. http://www.leapsecond.com/pic/picdiv.htm http://www.leapsecond.com/pic/picpet.htm One approach is to use a picDIV to make a PPS and then monitor that. If you have Linux, you can feed the PPS to a serial port. My hack for counting 60Hz will work fine at 1 Hz. http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz.py Another approach is to use a picPET and connect a modem control signal from the monitoring PC to the Event input on the picPET. Then the data collection program grabs the time, flaps a modem control signal, grabs the time again, then grabs the text from the picPET and logs everything. -- These are my opinions. I hate spam. _______________________________________________ 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.
