Hi Martyn: An important aspect is to properly set the trigger levels for each input. A mistake I made early on was to ass-u-me that the 1 PPS trigger level should be half of 5 Volts, i.e. 2.5 volts, but that's very wrong. The best approach is to install a BNC-T connector at the front panel and use a scope probe to look at the signal. The best place to trigger is at the steepest slope.
Have Fun, Brooke Clarke http://www.prc68.com/P/Prod.html Products I make and sell http://www.prc68.com/Alpha.shtml All my web pages listed based on html name http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Web Cam Martyn Smith wrote: > Hello, > > Thanks to all for your replies and suggesting especially Brooke, Bruce and > Pete. > > I am already using the Stanford technique with the 1 kHz output. That's how > I get 2 x 10E-12/sec accuracy. > Using this technique, the accuracy should be 7.9 uHz at 10 MHz (7.9E-13). > But I don't reliably achieve this. I reliably get 20 uHz, sometimes 10 uHz > and I do have resolution to parts in 10E-13, but the last digit isn't > reliable. > > Brooke do you do better than me here with this technique? I see you publish > results with accuracy better than I can achieve, I was wondering how you do > it. > > I think the answer from Bruce identifies my problem. I need to take more > care with my measurement techniques > > If it was easy, people wouldn't charge $20 - 50k for a box that dies it > well. > > Thanks all again > > Martyn > > > > _______________________________________________ > 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.