[aprssig] GPS off track
vk5jfk at activ8.net.au
Wed Apr 2 04:17:31 CDT 2008
Our maps here in Australia use the WGS84 datum
Stephen H. Smith wrote:
> What datum are the GPS units set for? If they are not set to WGS84
> (WORLD Geodetic System 1984) mode, you will see hundreds of feet error.
> This is a constant issue in the U.K. where many paper and electronic
> maps use the British Ordinance Survey datum rather than the WGS84
> datum that is native and default on most GPS devices. Google Maps
> (used by both findu and aprs.fi) are aligned with the world-wide
> GPS-inspired WGS84 datum. Many British APRS users set their GPS
> units to use the UK ordinance datum to make posits line up on their
> own maps; only to see major errors when they view themselves on Findu
> or aprs.fi.
> I would guess that Australia and New Zealand may also suffer from this
> problem of a "local" datum in use rather than the world-wide WGS84.
> (The Brits established numerous local datums during the centuries of
> the British Empire in places all over the world.)
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