Hi If I remember correctly, the inboard clock was chosen to be a "good source of noise" during the calibration process. It's certainly not a high stability clock.
Bob On Aug 15, 2010, at 12:25 AM, "John Miles" <[email protected]> wrote: > >> John glad you are getting good results and have something to >> compare to. Back to >> me who doesn't have any knowns but lots of guessing. Attached is >> a run with a >> box cover over the pictic, run is shorter ~ 800 seconds but the >> box does look >> like it helps. >> I need to do a lot more testing but sometimes I just get excited :-) > > I imported your .txt file alongside the traces I captured. Assuming it was > taken with 1 Hz on both START and STOP, it looks like the attached. > > You're getting the exact sort of results that I see if I feed both the START > and STOP inputs at 1 Hz. My guess is that the onboard oscillator limits the > performance in that case, since it has a lot of time to drift during the > measurement if the two pulses occur close to 1 second apart. Even the 5370B > looks much worse if driven with 1 Hz on both inputs than it does with 1 Hz > at START and 10 MHz at STOP. > > So I think you're basically up and running OK. When I get around to trying > a better clock, I'll also go back and see if the 1-pps x2 performance > improves. > > It would be great if the next spin of the board could include sine-to-CMOS > shapers for the input channels as well as an external clock input, for > people who are working directly with RF signals as opposed to 1-pps. > > -- john, KE5FX > > >> ----- Original Message ---- >> From: John Miles <[email protected]> >> To: Discussion of precise time and frequency measurement >> <[email protected]> >> Sent: Sat, August 14, 2010 10:19:46 PM >> Subject: Re: [time-nuts] PicTic Data >> >> A few preliminary measurements here (I'm working on getting some software >> support together): >> http://www.ke5fx.com/pictic.htm >> >> -- john, KE5FX >> >>> -----Original Message----- >>> From: [email protected] [mailto:[email protected]]on >>> Behalf Of Stanley Reynolds >>> Sent: Saturday, August 14, 2010 7:12 PM >>> To: Discussion of precise time and frequency measurement >>> Subject: Re: [time-nuts] PicTic Data >>> >>> >>> >>> >>> My guess as to what the data may indicate is performance of the >>> 10 Mhz 20PPM >>> PICTIC internal oscillator, need to repeat test with precision >>> 10Mhz and auto >>> calibrate off. Fatness of the line/width maybe PICTIC error. Note >>> graph seems to >>> show me leaving the room and returning via the outside door. Not >>> sure what the >>> ~100 sec oscillations are, need to check a/c cycle time. >>> >>> Stanley >>> >>> _______________________________________________ >>> 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. >>> >> >> >> _______________________________________________ >> 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. > <capture2_freq.gif> > <capture2_adev.gif> > _______________________________________________ > 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. _______________________________________________ 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.
