Tom, > I think the best of all worlds would be a double-ovenized > SC-cut OCXO running at 5 MHz (lower mass). These OCXOs have > the lowest phase noise and best Allen variance short term > stability (1-100 seconds) of any xtal or Rb. Then have this > OCXO disciplined by the GPS
this is the good part of the idea. > with an ephemeris of variations > constantly collected, statically averaged over a long period > (at least 1 month), and the calculated average used to adjust > the OCXO frequency. this is the bad part. Have a look to rb specs concerning environmental changes specially temperature or measure tempco of a rb yourself to see that observation times of this order make no sense! Best regards Ulrich Bangert > -----Ursprungliche Nachricht----- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von Tom Duckworth > Gesendet: Donnerstag, 24. April 2008 06:24 > An: 'Discussion of precise time and frequency measurement' > Betreff: Re: [time-nuts] Disciplining Rubidium > > > John, > > I think the best of all worlds would be a double-ovenized > SC-cut OCXO running at 5 MHz (lower mass). These OCXOs have > the lowest phase noise and best Allen variance short term > stability (1-100 seconds) of any xtal or Rb. Then have this > OCXO disciplined by the GPS, with an ephemeris of variations > constantly collected, statically averaged over a long period > (at least 1 month), and the calculated average used to adjust > the OCXO frequency. > > Tom > Tom Duckworth > 510-886-1396 > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf > Of John Miles > > Sent: Wednesday, April 23, 2008 8:02 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Disciplining Rubidium > > Adding to Tom's worthy list: > > 11) Short-term phase noise; the GPS-Rb sources don't seem to > be as clean as the better GPS-OCXO packages. > > -- john, KE5FX > > > > More precisely, if I had two black boxes, one containing > > > a GPS-Rb-XTAL setup and another containing GPS-XTAL, > > > what measurement would you make from outside the boxes > > > to distinguish from one another? > > > > Ah, clever question. Here's ten ways to distinguish them... > > > > > _______________________________________________ > 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.
