Hi Bob, As always, thanks for your informed help. I had been reaching the same conclusion, but needed unbiased confirmation. I think the RUBY4 software does what I want? I'll look into it.
Bob >________________________________ > From: Bob Camp <[email protected]> >To: Discussion of precise time and frequency measurement <[email protected]> >Sent: Wednesday, September 18, 2013 5:01 PM >Subject: Re: [time-nuts] GPSDO vs Rb standard > > >Hi > >One cycle of 10 MHz would be 100 ns. 100 ns per second would be 100 ppb. 100ns >per 20 seconds would indeed be 5 ppb. > >Since the Rb is *stable* but not *accurate*, the real question is - how much >does the 5 ppb change by? The Rb can't tell you if the GPSDO is correct. The >best it can do is tell you if it changed. If you can demonstrate that the >GPSDO is locked up, and that it's stable for many days, you can reasonably >conclude that the GPSDO is accurate. > >I'd say the first step is to get the Rb tuned closer to the GPSDO. You should >be looking for < 0.01 ppb changes. That's going to be tough with a 5 ppb >offset. > >Bob > >On Sep 18, 2013, at 5:47 PM, Bob Stewart <[email protected]> wrote: > >> I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz >> GPSDO to Channel A, .05us trace, and turned the lights out so I could >> see it. The 10MHz is marching right to left about 1 cycle every 20 >> seconds. So, can I say that the Rb considers my GPSDO to be too fast by >> about 5ppb? >> >> >> Bob >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. > > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
