On Sat, Mar 1, 2014 at 8:05 PM, Bob Albert <bob91...@yahoo.com> wrote: > 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 <hmur...@megapathdsl.net> > 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 -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.
-- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.