Bob has stated this, but perhaps not emphasized that, when you sample the phase of a 10 MHz clock once a second, you are essentially folding the 20 millionth nyquist band down to baseband. So you can alias any integer multiple of 1 Hz as if it were 10 MHz, i.e. 10 MHz + 1Hz will hold phase to 1 Hz (sampled once a second) just as well as 10 MHz would.
On Thu, Nov 3, 2016 at 1:00 PM, Bob Camp <kb...@n1k.org> wrote: > Hi > > If your TCXO is off by 1 ppm, it will slip 10 cycles per second at 10 MHz. > If it is off by 0.1 ppm it will slip a full cycle at 10 MHz. > If it is off by 0.01 ppm *and* uses some sort of digital compensation, it > will hop around. > If the GPS is not sawtooth corrected it will hop by a good fraction of a > cycle at 10 MHz > If the GPS is not surveyed in and seeing many satellites, it may hop by > more than a cycle at 10 MHz. > > Best bet: > > Divide the TCXO down to a much lower frequency (< 100 Hz). Use the 5370 to > look at the > delta between the GPS pulse and the TCXO output. > > Bob > > > > On Nov 3, 2016, at 9:22 AM, Peter Reilley <preilley_...@comcast.net> > wrote: > > > > I am using the 1 PPS for the trigger. > > > > Pete. > > > > > > On 11/3/2016 8:59 AM, Antonio A. S. Magalhaes wrote: > >> > >> Pete, > >> > >> Tell us about your trigger: where is it? > >> > >> Regards, > >> > >> Antonio/CT1TE > >> > >> --- > >> > >> A 2016-11-03 12:20, Peter Reilley escreveu: > >> > >>> I am the proverbial man with too many clocks and I don't know what > time it is. > >>> To correct this situation I have decided to calibrate everything. > >>> > >>> I have a HP 5370B, a HP 6370A, and a HP 5328A all with the TCXO > option. I also > >>> have some TCXO modules. I figured that I would calibrate them > against my Trimble > >>> Resolution T GPS receiver. > >>> > >>> I put the 1 PPS signal in one channel of my scope and one of the 10 > MHz TCXO > >>> signals in the other channel and look at the phase relationship. The > TCXO's are > >>> already close enough that I should not be out by more than a fraction > of a waveform. > >>> I understand that I have to deal with the 1 PPS without sawtooth > correction. > >>> > >>> I expected to see the 10 MHz signal bounce around but not move more > than 1/2 > >>> of a wave length. Instead I see the 10 MHz waveform appear steady > for a few seconds > >>> then jump a significant portion of the wave. The jump is too much to > be confident > >>> that I have not slipped one cycle. > >>> > >>> Can I do what I am trying to do or am I missing something? > >>> > >>> Pete. > >>> > >>> _______________________________________________ > >>> time-nuts mailing list -- time-nuts@febo.com <mailto: > time-nuts@febo.com> > >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > >>> and follow the instructions there. > > > > _______________________________________________ > > 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. > > _______________________________________________ > 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. > _______________________________________________ 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.