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On 3/23/2012 8:47 AM, Dave Walden wrote:
> I should add, in many comparisons between GPS, internet, and "atomic"
> watches, I've never seen a full second diff, much less a minute, but
> I'll go check some more.

I have defenitely seen this.  After the clock auto reset last midnight,
the cloxk was almost a second fast, although the were in sync mid day.
As an experiment, I should place it in the basement for without signal
to observe any gain or loss.
>
> I never found a good explanation of the sync symbol. My assumption is
> that it means the last time it tried to sync, it was successful. This is
> based on moving the clock and watch away from from the window where the
> sync works for a while and by watching when they update for DST.

As  mentioned, I have 2 "atomic" clocks.  The first was a Sharp (a good
brand name in the USA) purchased at Wal Mart. Its ability to receive a
signal automatically or manually, even out of doors at midnight was
virtually non existent--5% or less success. Perhaps a lemon, so I tried
to exchange it but there were no more in stock and they never returned
to the shelf. It now lives in the basement next to my computer, set to
UT. On. the upside while it receives no signals, it has gained only 6
seconds since the last time I reset it manually over 2 years ago--an
order of magnitude better than my Casio wrist watch. That I find hard to
believe.

The second is a Presidian, a brand name I had never heard of.  I
purchased it at Radio Shack.  It has been, to the best of my knowledge,
flawless.  Its calender recognizes leap years, and also auto-resets the
hour for the EDT/EST transitions. It lives near west facing window in a
3-seasons room, facing CO.

The Presidian shows a square "Wave OK" box indicating that it reset
itself successfully the last time it tried.  It tries every midnight. If
it fails, it retries every 4 hours until it succeeds. There is an
antenna symbol next the "wave set" box with 4 bars above it.  This
flashes when the clock is seeking a signal.  I assumed the bars were
signal strength like the Sharp, but that is not documented for this unit.

If I understand, in Gary's case once it goes off by a minute, it has to
be manually reset, and then may repeat the behavior.  Given a few days
it will self correct its error.

Thanks you all for your input.

Bill B

   

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