[time-nuts] Racal-Dana 1992 switches

Tom Duckworth tomduck at comcast.net
Thu Apr 3 03:01:53 EDT 2008

Bruce & Rex,

You're both right. 1.25E-10 was for 40.000 000 005 GHz and 7.5E-11 is for
40.000 000 003 GHz. My bad, Good sleuthing.

Tom Duckworth
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Rex
Sent: Wednesday, April 02, 2008 3:01 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Racal-Dana 1992 switches

Bruce Griffiths wrote:
> Tom Duckworth wrote:
>> Bill,
>> I have attached a PDF of two methods we used at XL Microwave for
>> the internal reference oscillators in our microwave counters. The second
>> method (digital) was used to calibrate the internal reference time base
of a
>> 70 GHz microwave counter with an accuracy of parts in E-11.
>> This digital method could be used to compare two GPSDOs, one to the
>> and would probably yield greater resolution than trying to use a phase
>> measurement on a counter due to jitter, internal noise, and stability
>> in the count chain. This method proved to be fast, simple, stable, and
>> superior to other methods we tried.
>> Hope this helps.
>> Tom
>> Tom Duckworth
>> 510-886-1396
> Tom
> The first calculation at the bottom of the second page is incorrect the 
> result should be: 1.25E-10 not 7.5E-11.
> Bruce
The result was fine, but the measurement should have been 40.000 000 003 
GHz.  :-)


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