Hi Bruce, > The GPS altitude is calculated with respect to the geoid.
No, the GPS calculates altitude wrt the ellipsoid. Then its a conversion with lots of coefficients or a lookup table to add the geoid separation. Altitude wrt to the geoid is the same as Mean Sea level, which is what normal maps etc gived height in. -- Björn > The geoid surface may have a vertical separation from the actual surface > by several meters. > This correction varies with location on the Earth's surface. > > Bruce > > Michael Baker wrote: >> Hello, TimeNutters-- >> >> While we are on a thread about Trimble T-bolts, >> perhaps someone might expand on why my T-bolt >> does not ever come up with altitude readings that >> are even close. After a long fix, the Lat-Lon >> coordinates are pretty close, but the altitude >> is always given as around 2 meters. We are pretty >> low here in Flori-DUH, but not THAT low. My >> ground elevation here is 28M ABMSL and my >> GPS antenna is another 8M above that on top >> of my fireplace chimney. I have roughly 50 ft >> of RG-59 cable on the antenna, but altering the >> cable length value does not seem to have any >> effect. I get these same very low altitude readings >> with TBOLTMON and Lady Heather v3 beta. >> >> Since I know my altitude well withing one meter, >> should I enter that manually? What is the >> procedure for doing that? >> >> Suggestions...?? >> >> Thanks!! >> >> Mike Baker >> ------------------- >> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
