I suspect, Wayne, that the GPS units would be accurate for most of the time,
but would have excursions to ridiculous readings, presumably if the unit lost
lock on sufficient satellites and the position was wrong for a period of time
before being updated. The sudden change of position would be interpreted as
movement for a short time before the unit's logic worked it through the system.
That's how most of the navigations systems have worked in the aircraft that
I've flown. They were all great, as long as you knew where you were and where
you were going :-) -- so that you could monitor them. I never trust systems
completely. It's for similar reasons that I refuse to trust man-made
organisms, such as GMO . . .
Chris
On 19 Jan 2013, at 12:36, Wayne Harridge <wayne.harridge@xxxxxxxxxxxxxxxxxxx>
wrote:
> My previous employer had GPS units in trucks reporting back to a central
> server. In some instances the GPS units reported obviously inaccurate
> speeds (fairly often in excess of 150kph, one I noted @275kph !). The GPS
> units generally appeared to behave ok and these spurious speeds would only
> be registered for a few samples over a day. The problem was that you could
> never be really certain of the speed, if the unit registered 100kph over the
> legal limit you could say it was spurious, but what if it was 10kph over the
> limit, spurious or actually speeding ? I presume too that if the GPS units
> were registering spurious high speeds they probably were registering
> spurious low speeds also.
--
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/
|