From: Bruce Griffiths <[EMAIL PROTECTED]> Subject: Re: [time-nuts] GPS noise reduction Date: Sun, 06 Apr 2008 14:30:52 +1200 Message-ID: <[EMAIL PROTECTED]>
> METHOD 2: > If one uses an ADC to sample say a 1MHz sinewave (produced by dividing > down the OCXO frequency and low pass filtering) on the PPS edge then > subnanosecond resolution combined with the ability to make software > corrections of the sawtooth error is possible. A refined method is to use a sine and a cosine, since these have their worst slope errors when the other has its best. But you can get far on just a sine. A classic method is to count time in a coarse clock and then produce an error signal which is integreated into a capacitor and then either converted into a longer pulse using a much lower discharge current. Another method is to use an ADC and then only clear the capacitor. Either way allows for easy access to x10 to x100 increase in time resolution. Really a handfull of stuff being not that exclusive and esquicit. Reaching for 1 ns to 100 ps resolution is doable. Cheers, Magnus _______________________________________________ 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.