Re: GPS measured elapsed distance

Robbie <robbiex@xxxxxxxxxxxxx> writes:

>I would like to share programming experience with those who have worked
>on public domain software for GPS measurement of elapsed distance.
>There are two basic approaches: one using rate x time and the other
>adding the distances between frequently obtained coordinates along a
>track. It is not a trivial problem due to position variability when the
>GPS is not in motion, limitations of the (PDA) programming languages
>regarding date-time data, and difficulties obtaining a regular "time
>tick" that is synchronized with the transmission of the GPS motion data.

Why do you need special software? I find that the trip distance total
on my GPS matches to the distance recorded by my bicycle computer
(based on wheel revolutions) to within 2%. On the few times when it
goes from less than 2% to more than 2% but less than 5% the reason is
obvious and easily discovered by inspection or by software: loss of
satellite reception for some time. And once in a few hundred trips I
got an error of a few thousand per cent, but again the reason was
obvious: a spurious position fix which had me travelling
hundreds miles at near the speed of light.

BTW, you shouldn't even be working with such a crap programming
language that you actually have "limitations with regard to date-time
data"!
--
Chris Malcolm cam@xxxxxxxxxxxxxxxxxxxx +44 (0)131 651 3445 DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]

.

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