[time-nuts] Comparing Reference Accuracy

Stanley Reynolds stanley_reynolds at yahoo.com
Thu May 22 18:54:21 EDT 2008

----- Original Message ----
From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Thursday, May 22, 2008 5:09:32 PM
Subject: Re: [time-nuts] Comparing Reference Accuracy

Stanley Reynolds wrote:
> The prams for sample size could also be set in the sampling PICs you would probably want to set them all the same.

A much better scheme is to time stamp the leading edges of the various 
PPS signals (from the GPS receiver and the divided down output of each 
GPSDO) using a common time base.
The time stamp resolution is improved by using a higher frequency clock 
and/or a time interval interpolator for each input channel.
This is the scheme used by NIST for remote frequency measurement.


Getting back to the idea that the DO controller needs to measure the oscillator to make corrections, would your suggestions make a better DO controller if used in this measurement ?  Or maybe instead of just measuring the difference between a group of DOs, we generate a improved standard from the group canceling their unique errors. This would force us back to real time so post processing would be out.
I do understand that we need a better ruler to determine how good our ruler is, but at some point we improve to a group that is at the same level by elimination of the out-lye-rs. Or in my case the limit that I'm capable of implementing at this point.


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