[time-nuts] Garmin GPS12XL V3.51

[Tony Finch]

Leo Bodnar <leo at leobodnar.com> wrote:

> Assume that the device does not have any reliable long term non-volatile
> memory that you can update.

> In the absence of any clues your only reliable piece of knowledge is
> that the cold start date is somewhere after the date of manufacturing
> or, most often, firmware compilation date.

There's another relatively simple clue in the old GPS signal: the leap
second count! A device manufacturer could teach it what the leap second
count was at manufacturing time, and how to predict a lower bound on the
leap second count in the future (with a suitable safety margin / fudge
factor) which should allow it to live a bit more than 20 years.

Tony.
-- 
f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/
Gibraltar Point to North Foreland: Northeasterly 5 or 6, occasionally 7 in
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