[Test-Equipment] Frequency accuracy

Wed, 25 Sep 2002 06:33:10 -0400

Francesco -

Good morning. Well at least it is morning here. I will check out the web
site you suggested. I more than likely have seen it previously. I have met
Dave Allen and Fred Wahls on a few occasions. I probably should not have
resorted to referring to Allen variance as a possible solution. However, I
still feel that some sort of statistics will have to be applied, and
numerous measurements taken. This is all assuming that the transmitted
source will be at a constant frequency for a given time, and as you pointed
out, the rate of change of propagation delay is either zero during the
measurement interval, or behaves such that simple averaging will minimize
it's effects. With all the projects at hand, this sounds like a fun event,
and even if the ARRL does not do it, maybe some of us should. Regardless, it
will be a learning experience, and that is what it is all about. Thanks &
Regards - Mike

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

----- Original Message -----
From: "Francesco Ledda" <[email protected]>
To: "Mike Feher" <[email protected]>; <[email protected]>;
<[email protected]>
Sent: Wednesday, September 25, 2002 6:10 AM
Subject: RE: [Test-Equipment] Frequency accuracy

> Mike,
>
> Here is a link to some interesting readings about clocks and clocks
> characterization.
>
> http://www.allanstime.com/AllanVariance/
>
> Good luck,
>
> Francesco
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Mike Feher
> Sent: Tuesday, September 24, 2002 6:46 PM
> To: Francesco Ledda; [email protected]; [email protected]
> Subject: Re: [Test-Equipment] Frequency accuracy
>
>
>
> In your initial post you mentioned the ionosphere, not the oscillators. It
> is all a function of the desired accuracy, but we were mostly discussing
> disciplined oscillators. Therefore, I still feel, that the statistics
> required is that for the measurement equipment. Additionally, of course,
> then according to you, the source, to be measured, would suffer the way.
So,
> if we have a source that is not stable as a function of time, and
> measurement equipment suffering the same problem, it is a hopeless
> situation. BTW, I believe  I have a way to get the signal frequency to be
> measured, locked, and looked at with an FFT analyzer. Regards - Mike
>
>
>
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell NJ, 07731
> (732) 901-9193
>
>
> ----- Original Message -----
> From: "Francesco Ledda" <[email protected]>
> To: "Mike Feher" <[email protected]>; <[email protected]>;
> <[email protected]>
> Sent: Tuesday, September 24, 2002 6:54 PM
> Subject: RE: [Test-Equipment] Frequency accuracy
>
>
> > No, I was referring to oscillators in general.  Since oscillators drift
in
> > time, the estimate of the mean is meanness.  This means that increasing
> the
> > observation time does not improve the accuracy of the mean estimate.
> >
> > Regards, Francesco
> >
> >
> >
> >
> > -----Original Message-----
> > From: [email protected]
> > [mailto:[email protected]]On Behalf Of Mike Feher
> > Sent: Tuesday, September 24, 2002 4:40 PM
> > To: [email protected]; [email protected]
> > Subject: Re: [Test-Equipment] Frequency accuracy
> >
> >
> >
> > Remember, back then we had to use counters that took a long time for a
> > single measurement, especially of the precision that you are talking
> about.
> > There were no such things as reciprocal frequency counters at the time.
> > Additionally, as I recall, the 60 KHz transmissions were modulated with
> > embedded time and other data, and is, like now, far from a steady
carrier.
> I
> > have had several private emails with other contributors to this thread,
at
> > their choice, and actually wish the whole group could have benefited or
> > contributed to them. This reflector is not a real busy one, so this
> > discussion, at least to me, has been really interesting. This is a neat
> > topic, and I hope the thread continues. Francesco earlier mentioned that
> the
> > statistics associated with the measurement cannot necessarily be
> considered
> > Stochastic, or time invariant. Of course he was referring to the
> atmospheric
> > phenomenon. At the time, my argument for a statistical measurement was
due
> > mainly to test equipment variances as a function of time. I am still
> willing
> > to listen and learn, as this is a fascinating phenomenon for me.
Regards -
> > Mike
> >
> >
> >
> > Mike B. Feher, N4FS
> > 89 Arnold Blvd.
> > Howell NJ, 07731
> > (732) 901-9193
> >
> >
> > ----- Original Message -----
> > From: <[email protected]>
> > To: <[email protected]>
> > Sent: Tuesday, September 24, 2002 5:09 PM
> > Subject: [Test-Equipment] Frequency accuracy
> >
> >
> > > I wonder if any of you have ever received the 60KHz from WWVB and
> plotted
> > > it against WWV at 5 ,10, or 15MHz. It should give you a new idea of
> > > propagation errors and frequency comparison accuracies. Do you
remember
> > how
> > > we used to plot a comparison with WWVB and the House Standard and hope
> > that
> > > we were accurate to 10 to the -10th?????
> > > n5mqa
> > >
> > >
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