[time-nuts] Cs stability

Magnus Danielson magnus at rubidium.dyndns.org
Tue Jul 17 04:26:24 EDT 2007


From: "Tom Van Baak" <tvb at LeapSecond.com>
Subject: Re: [time-nuts] Cs stability
Date: Tue, 17 Jul 2007 00:40:49 -0700
Message-ID: <004b01c7c845$cb81d290$0300a8c0 at pc52>

> ); SAEximRunCond expanded to false
> Errors-To: time-nuts-bounces+magnus=rubidium.dyndns.org+magnus=rubidium.dyndns.org at febo.com
> 
> > In the article "OBSERVATIONS ON STABILITY MEASUREMENTS
> > OF COMMERCIAL ATOMIC CLOCKS", Pekka Eskelinen claims to
> > have measured a phase temperature coefficient of 100ns/degree
> > for commercial Cs clocks in 1999.
> 
> Something is wrong with that claim. There's no way a modern
> cesium standard exhibits a phase shift of 100 ns for a one
> degree change in ambient temperature. I have Cs standards
> that often change in temperature by several degrees and still
> keep to nanoseconds. I guess I need to decode that paper
> and see what's wrong.

I think the paper lacks a number of necessary details in order to fully
understand the conditions under which this exercise took place. There is no
clear list of equipment used. It can be implied that it is 5071A being used.
What Time Interval counters where used is for instance not known.

He have compared PPS outputs between GPS receivers (which model are those?)
and Cesium. 

I'd like to see some investigations into how stable the GPSes and measurement
equipment is to temperature.

In the end, there are a few pages of material missing in there for it to give a
fairly comprehensive picture. Many of these issues could probably be cleared up
after some discussions with the author, but we should not have to rely on side-
channels like that.

It's an interesting article, but it leaves me with a few questionsmarks. It is
a bit unsatisfying.

> Does anyone have contact with the authors (Finland)?

Should not be too hard as his email adderess is at the top of the first page.

Cheers,
Magnus



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