[gpsd-dev] ✘

[Gary E. Miller]

Yo All!

FYI: 

Subsequent to last weeks dicussion on gpsd-dev, there are some changes
to the TPV altitude data.

Three, incompatible, things were being stuffed into gps_data_t altitude:
        altitude height above ellipsiod (WGS84) in meters
        altitude height above geoid (MSL) in meters
        depth in negative meters

The old variable altitude has now been replaced in gps_data_t and
the TPV JSON by:
        altHAE: altitude height above ellipsiod (WGS84)
        altMSL: altitude height above geoid (MSL)
        depth: depth in meters

cgps now display altHAE and altMSL.

The wgs84_separation() calculation has been updated.  It now does a
bilinear interpolation to the EGM2008 datum.  The base dataset
was increased from a 10x10 degree table to a 5x5 degree table.  So
calcualted geoid separation improved a nit, but can still err by
up to 12 meters.  Best to post process altHAE if you need an accurate
altMSL.

NEWS and gpsd_json.1 updated to match.

The result is cleaner and clearer data.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin

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