Tony Verhulst wrote:
Though much better thatn the 121.5 MHz units, I don't believe that the
406's transmit GPS coordinates like the 1.6 GHz units do - they use
doppler shift instead. My understanding is that the 406 MHz units
provide a 1KM resolution. Much better than the 121.5's but if you go
down into a forest.... not good enough, IMHO. See
http://www.navtec.de/english/elts.htm

A 406 MHz ELT can transmit GPS position. I believe EPIRB was designed
primarily for marine applications. The primary receivers are on
geostationary satellites, which may not be very helpful if you happen to
be in a canyon, or on the wrong side of a mountain...

Marc