AIS transmissions

thataway · Posted: Mon Dec 21, 2020 10:41 pm Post subject:

Harvey had pointed out the limit was not 500' but 500 meters, or about 1640 feet.

Garmin's main stream of revenue is also aeronautical products, so they have a lot of experience with GPS at elevation. (2018 figures show $158 million for aviation and only $95 million for marine, $255 million for "outdoor" and $277 million Fitness and $148 for automotive/vehicular. So the marine division is the lowest revenue producer! The aviation, outdoor, Fitness and vehicular all have high elevations, and many of the hand held GPSsnow give elevation. The watch uses GPS to locate for known elevations and also barometric pressure. Heck, I have two watches (which give me elevation which is fairly accurate to a meter or so.

GPS data does have to be corrected for elevation since GPS assumes that the earth is an ellipsoid. There are random variations from that ellipsoid which have to be corrected. I think developing the database and then applying it to the GPS altimeter has been the issue. But it should have nothing to do with AIS signals...