Yes, and, as you can see, you have to wait 1 hour. On Thu, Apr 19, 2012 at 9:49 PM, <saidj...@aol.com> wrote:
> Hi Wolfgang, > > one of the easiest and very accurate ways to do this is simply to measure > the drift of the two 10MHz signals on an oscilloscope. Adjust the OCXO so > that this drift between the two traces is as slow as you can get it. Then > simply measure it over time. Use one signal for trigger, the other to > display > if you only have a one channel scope. > > If you get say 10ns drift over 1 hour (which you can easily measure even > with the cheapest scopes), that is a resolution of 10ns/3600s = 2.78E012. > > Or in other words 27.7uHz! > > This has been discussed before and documented in the time nuts archives > some time ago. > > bye, > Said > > > > > In a message dated 4/19/2012 12:10:53 Pacific Daylight Time, > skywatc...@web.de writes: > > My first approach was to use a simple XOR phase comparator. I tried a > 74HCT86 and a 74HCT4046. > It works, but it's very noisy, so i don't get better than about 10 mHz > frequency resolution. > If i look at the lowpass-filtered output i don't see a nice sine or > triangular wave, but it looks more > than a triangular wave with round tops and some bumps between them. > Another problem is that the > difference frequency gets very low when the frequencies are very close, > so it's not enough to look > only for zero crossings of the difference signal. > > Does anybody know a possibility to get a resolution < 1 mHz ? > > Best regards, > Wolfgang > > > > _______________________________________________ > 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.