[Test-Equipment] Frequency Measuring Test

Tue, 24 Sep 2002 11:34:58 -0400

Gary -

That is of course correct, and I have not considered it. The good old rate
of change in phase as a function of time does equal a change in frequency.
However, I would not expect propagation delays to change so abruptly,
although, here again, this is out of my expertise, and, we are talking about
minute differences, so, it could well cause a measurable difference. But, it
does reaffirm my earlier statement about the measurement having to have a
statistical basis, made up of multiple measurements and intervals. 73 - Mike

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ, 07731
(732) 901-9193

----- Original Message -----
From: "Gary Chatters" <[email protected]>
To: <[email protected]>
Sent: Tuesday, September 24, 2002 10:36 AM
Subject: Re: [Test-Equipment] Frequency Measuring Test

> >
> >I do not believe that propagation delays will cause frequency measurement
> >errors. Unless we are talking about something like doppler. Plain delay
> >should have no effect. It will however have an effect on any time related
>
> Of course, delays are not going to cause errors.  The problem is in
> the variations of the delay.  Those with GPS based standards might
> find it interesting to measure WWV.
>
> I made a fairly simple set up for comparing frequency to WWV.
> A Racal 6790/GM tuned to 10MHz with its BFO offset by 60Hz is
> fed to an oscilloscope set to line triggering.  The trace would
> be fairly steady for only a few seconds before the ionosphere
> started shifting and the sine wave trace started racing across
> the screen in one direction or the other.
>
> Gary
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