[time-nuts] GPS clock error.
Max Robinson
max at maxsmusicplace.com
Thu Apr 14 04:15:34 UTC 2011
Hi Hal.
The manufacturers logo consists of the lower case letters ila next to an
hour glass. The instruction book calls it a talking atomic alarm clock. It
is somewhat of a battery hog. They have to be replaced every 2 or 3 months.
Regards.
Max. K 4 O D S.
Email: max at maxsmusicplace.com
Transistor site http://www.funwithtransistors.net
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----- Original Message -----
From: "Hal Murray" <hmurray at megapathdsl.net>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Wednesday, April 13, 2011 3:29 PM
Subject: Re: [time-nuts] GPS clock error.
>
>> This morning at 10 AM CDT my GPS clock read 8 PM July 5th. My wife
>> reported
>> that the time had been 2 hours off at 6 AM local time. She didn't
>> notice
>> if it was AM or PM. The parabolic dish icon was missing from the
>> display.
>> I manually set the time and date but when compared to my two WWVB clocks
>> it
>> was clear it was in holdover mode. I waited about 3 hours then removed
>> the
>> batteries and reinstalled them. ...
>
> Could you say more about this clock?
>
> How long do the batteries last? ...
>
> I'm familiar with battery operated "atomic" clocks that listen to WWVB. I
> didn't know about GPS versions.
>
> I'd expect a WWVB receiver to use much less power but maybe modern GPS
> receivers are good enough so they would have reasonable battery life.
>
> My best guess is that your receiver got tricked by noise that looked good
> enough. I've seen GPS receivers report that their info was valid when it
> was
> miles from the reported location. Usually, that's right after recovering
> from not-enough-satellites.
>
>
> albertson.chris at gmail.com said:
>> There are also endless ways that logic inside th GPS can fail in a "soft"
>> way. Memory can become pattern sensitive or a tiny sense amp in a RAM
>> chip
>> can get noisy and cause one in a billion type soft errors. I don't
>> bother
>> to fix things until I can make it repeat on demand
>
> Memory doesn't usually "become" pattern sensitive. It might be designed
> that
> way.
>
> Cosmic rays or alpha particles are the usual ways that DRAM gets soft
> errors.
> You can also have noise/crosstalk at the board level (or on chip) or power
> supply problems.
>
> If you want to build a reliable system, you have to pay attention to rare
> bugs. If nothing else, you want to collect data on them so you know if
> you
> have a problem and/or how bad it is.
>
>
>
> --
> These are my opinions, not necessarily my employer's. I hate spam.
>
>
>
>
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