[OSM-newbies] Garmin eTrex 20/30 - is altimeter important for recording GPS data for mapping?

[Bill Ricker]

On 1/31/13, Cartinus <cartinus at xs4all.nl> wrote:
> The Garmins don't have a pure barometric altimeter. They combine the
> height from the GPS measurements with the barometric pressure. They are
> "auto calibrated" over a period of twenty minutes.

Based on recent experience, I am quite certain that is not true of
older models e.g. 76csx, or if true, auto-calibration is not very
accurate.  The interstate tunnels under Baltimore Harbor should give
me accurate indication of sea-level in-and-out if I started more than
twenty minutes away with good sky view, and it was quite off.


-- 
Bill
@n1vux bill.n1vux at gmail.com