Re: [Paddlewise] GPS errors

From: Joe Pylka <pylka_at_castle.net>
Date: Sat, 13 Mar 1999 21:52:53 -0500
>Would this discrepancy be due to improper factory calibration of the unit,
or
>can a unit slip out of calibration?  Or might the discrepancies be due to
the
>installation of the ship-mounted unit, or what?  Inquiring (armchair)
>navigators want to know.
        Almost always, this sort of discrepancy is due to setting the wrong
reference datum into the receiver.  Most topo sheets use NAD27 (North
American Datum, 1927) as their baseline for measurement.  There are many,
many others.  Chances are the discrepancies were all almost the same
distance, and always the same distance and direction of displacement as
well.
        In effect, GPS receivers don't go out of calibration because they
constantly update their references which are continually downloaded from the
satellites.

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Received on Sat Mar 13 1999 - 18:51:30 PST

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