Altitude data from GPS

SteveTh · Occasional Visitor Joined: Mar 02, 2004 Posts: 3

Should the altitude data received from the GPS correlate with the altitude data given on on OS map or are they using different datums (is that the plural of datum??)
My Fortuna Clip-On seems to be consistently high by about 30.000m
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iPAQ2210, Fortuna Clip-On, TomTom2, Memory-Map2004

lbendlin · Posted: Thu Mar 04, 2004 3:20 pm Post subject:

30 meters is pretty decent.. Don't forget that the VDOP is often higher than the HDOP. Additionally, somewhere here is a trhead sleeping that goes into great detail about how certain receiver firmware versions (for the SiRF II chipset) are calculating the altitude correction from the WGS84 wrongly - either they ignore it or they add it up the wrong way.
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Lutz

Report Map Errors here:
TomTom/TeleAtlas NAVTEQ

Robin2 · Posted: Fri Mar 12, 2004 12:18 am Post subject:

When I'm driving along the shore here in Swansea, CoPilot tells me that I am 400 ft above sea level!
Robin

lbendlin · Posted: Sat Mar 13, 2004 2:26 am Post subject:

remember, it may not be CoPilot's fault. It just repeats what the GPS receiver is saying.
_________________
Lutz

Report Map Errors here:
TomTom/TeleAtlas NAVTEQ

SteveTh · Occasional Visitor Joined: Mar 02, 2004 Posts: 3

The Ordnance Survey National GPS Network at www.gps.gov.uk refer to a Coordinate Converter written by QuestWEB at www.qgsl.com.
When I input my GPS coordinates and height data the utility tranforms it to the Newlyn datum and it is then as we would expect it to be as shown on OS maps.

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