Hi
> On Apr 23, 2017, at 12:43 PM, Richard Solomon <w1...@outlook.com> wrote: > > At that resolution, you need a very accurate and stable Time Base. > > A GPSDO may not be good enough for 10 e12 measurements. > If buy some truly strange chance, this *is* a 100,000 second gate time exercise (which I very much doubt) …. a GPSDO may well be just fine for that level of performance. It would need to have a good antenna location and to be in a reasonable environment. Other than that an OCXO based device should not have a lot of trouble after a couple days warmup. If somehow this morphs into a three sigma at 1x10^-12 accuracy at 1 second project then indeed, a GPSDO is not in any way going to be adequate to the task. You can pretty well extend that to 10 and 100 seconds without much chance of being contradicted. You also aren’t going to get that sort of accuracy at 1 second without doing a lot of heavy lifting counter hardware wise. The MCU choice becomes a very minor point on a fairly long list. Bob > > 73, Dick, W1KSZ > > > Sent from Outlook<http://aka.ms/weboutlook> > ________________________________ > From: time-nuts <time-nuts-boun...@febo.com> on behalf of Jerry Hancock > <je...@hanler.com> > Sent: Sunday, April 23, 2017 12:14:49 AM > To: Discussion of precise time and frequency measurement > Cc: met...@hanler.com > Subject: [time-nuts] Frequency counter questions > > Hello, I would like to find a person that would be able to answer some > frequency counter questions I have. > > Basically, I am thinking of building my own using one of the high end STM32F7 > boards as the counter. I would like it to count reliably to 12 digits (e.g. > 30,000,000.001x hz). I am not worried about input conditioning as I have a > circuit that is suitable for my needs. Most of my questions have to do with > using a prescaler on the front (divide by N where what is N) to get to the > desired resolution when using multiples of the PPS coming from my GPSDO. > Gate times could be as long as needed to get the resolution. So what > prescaler do I need and what gate time is required are the first two > questions. I suggest if someone is willing to help that they either reply > here with an email address or send a note to meters at hanler dot com. This > is for my own non-commercial use. > > Thanks! > > Jerry > _______________________________________________ > 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.
