[time-nuts] Predicting clock stability from thevariouscharacterizationmethods

[Tom Van Baak]

Brooke,

Maybe this helps. The clock prediction into the future
is based on the past history and the current point. If
the measured ADEV for a clock is, say 1e-13, for a
measurement interval of 1 day (tau), then the prediction,
within one standard deviation, is that you'll be within
1e-13 tomorrow. 1e-13 at one day is about 9 ns. I think
this is right. Can someone double check?

It shouldn't matter what your divider does -- 9 ns of
time error is 9 ns regardless if it's the zero-crossing
of a 5 MHz RF output of the leading edge of a 1PPS
signal.

A divider postpones cycle wrapping but doesn't affect
clock accuracy or stability (other than the obvious
introduction of passive & active component noise in
the signal path).

/tvb

----- Original Message -----
From: Brooke Clarke
To: Tom Van Baak ; Discussion of precise time and frequency measurement
Sent: Thursday, November 30, 2006 13:31
Subject: Re: [time-nuts] Predicting clock stability from
thevariouscharacterizationmethods

Hi Tom:

Is there a way to use the Allan plot to predict the variation in a reading?
For example if you use the plot comparing the 1 PPS from a GPS receiver to a
good Cesium frequency standard, then:
(1) what size of variation would you expect if the Cesium standard was
divided down to 1 kHz and that was compared to the GPS 1 PPS, or
(2) what size of variation would you expect if the Cesium standard was
divided down to 1 Pulse/1,000 seconds?

Have Fun,

Brooke Clarke