[time-nuts] Disciplining Rubidium

[Ulrich Bangert]

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: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] 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: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] 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...
> >
> 
> 
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