TELECOM Digest OnLine - Sorted: Re: Using Cell Phone For Frequency Calibration Reference?

Re: Using Cell Phone For Frequency Calibration Reference?

Scott Dorsey (kludge@panix.com)
31 May 2006 10:54:32 -0400

Richard Eldon BARBER <piano.tuner@yahoo.com> wrote:

> Some piano tuners calibrate electronic tuning devices using their cell
> phone. Is this a good idea? Calling up NIST on the cell phone, you
> can have 440Hz played to you. Is using a cell phone going to be a
> stable frequency reference? Will the cell phone network actually be
> able to preserve the frequency, say as 440.0000 Hz? or will there be
> frequency domain quantization errors due to wavelet compression, thus
> affecting the freq stability of the transmitted tone? Please post and
> email ...

I don't think it would be a serious issue, but try it yourself and
find out. Call the number with a conventional phone, then call it
with a cell phone. Hold the two phones together and see if you hear
any beat notes.

There will be some error. But if you can't hear it, it's not important.

--scott

"C'est un Nagra. C'est suisse, et tres, tres precis."

[TELECOM Digest Editor's Note: Or notice, for example, the setting
of accurate clocks via the internet. I've a program here called 'Net Time'
which constantly polls various 'time servers' around the net. When
you set it up, one site returns data reported to have latency of .150 ms
and another has latency of .75 ms, etc, in other words _none _ of
them display (on my screen) -exactly- the right time. But the
program takes a half dozen or so of these time servers, and averages
the latencies then makes an adjustment which is as close as one can
get apparently, to the 'correct time', but no one can ever discern
the difference, at least human eyes and ears are unable to find a
difference, which is what I suspect the original writer would find in
checking landline to cellular. If he can tell the difference, then his
hearing is better than mine. PAT]

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