John Kasupski wrote:
Note that we're probably talking errors in the amount of nanoseconds
(per second) here, certainly not errors that are going to cause
somebody to be ten minutes late for work, but for commercial or
scientific applications requiring a time reference that is related
directly to a national or international reference, GPS may not
necessarily cut the mustard.

Yes, but don't loose sight of the fact that this discussion is really
about consumer items. One person metioned in a previous post that his
clock syncs three times a week, other than that, it "runs free".

So IMHO if you build a consumer device that syncs every 5 minutes to
a GPS or GPS based standard, it will be a lot more accurate than
the average one that syncs every 2-3 days to a radio signal.

If it were to sync every minute to a time signal inserted in a cellular
control channel, it be even more accurate. Last I checked, the AT&T
Wireless 850mHz GSM (whatever name it is called now) network covers 98%
of the surface area of the U.S.

Since it is a receiver it can be broadbanded and if it were to cover
the GSM 850/900 mHz and 1800/1900 mHz bands it would work everywhere
there is GSM coverage. Except for Estonina and Brazil, an 850/900 mHz
receiver would be enough.

This does leave out parts of the Pacific Rim (Japan and Korea) and
some parts of Oz, but on the whole it cover almost the entire
populated earth.

Geoff.


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