[time-nuts] Disciplining Rubidium

wa1zms at att.net wa1zms at att.net
Thu Apr 24 00:36:31 UTC 2008


But doesn't it matter what your definition of "short term" really is?

I have some Wenzel OCXOs that hit 5E-13 for a 1 second tau. No Rb or Cs
or Z3801 that I have running get that good at 1 sec tau!  Over 10,000
is a different matter, however.


-Brian, WA1ZMS

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
Behalf Of Tom Duckworth
Sent: Wednesday, April 23, 2008 6:13 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Disciplining Rubidium


Antonio,

Absolutely! With a good XTAL you have parts in the 9th, short term. With a
XTAL controlled by a Rubidium, in the phase-lock feedback loop, you have
parts in the 12th, short term. With the Rubidium disciplined by the GPS,
with its on-board Rubidium/Cesium oscillators updated from the ground every
orbit, you have parts in the 14th, short term. In other words, your
XTAL/Rubidium/GPS has an effective short-term Allen variance equivalent to a
good Cesium; and better than a single Cesium, long term, for a lot less
money!

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 iovane at inwind.it
Sent: Wednesday, April 23, 2008 3:11 PM
To: time-nuts
Subject: [time-nuts] Disciplining Rubidium

Does it make any sense "GPS disciplining" a rubidium oscillator?
In such a case we have a chain made of
GPS - Rubidium - XTAL
as opposed to the simpler case of
GPS - XTAL
(assume that XTALs are of the same quality, and so the control loops).
Does the addition of Rb in the middle of the chain add
any real advantages?

Antonio I8IOV



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