[time-nuts] PicTic Data

[John Miles]

> 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 <jmiles at pop.net>
> To: Discussion of precise time and frequency measurement
> <time-nuts at febo.com>
> 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: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]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
> >
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