Summary:
http://www.backcountrychronicles.com/pl ... nyon-test/

Fuller descriptions:
http://www.itrsonline.org/PapersFolder/ ... SPaper.pdf

The test areas were not all as deep and isolated as implied by the photo in the summary.

They comment that no GPS data was received from several of these locations. The thing that you have to remember is that if you are carrying a GPS device, it needs more than just a bit of clear sky; it needs to receive at least 3 or 4 satellites in order to fix your position and three that are in a straight line won't begin to do the trick.

Buz Groshong wrote:They comment that no GPS data was received from several of these locations. The thing that you have to remember is that if you are carrying a GPS device, it needs more than just a bit of clear sky; it needs to receive at least 3 or 4 satellites in order to fix your position and three that are in a straight line won't begin to do the trick.

Many people will tell you that true PLBs are not dependent on GPS. However, the global PLB system uses two sets of satellites and two methods of location; one is a doppler method (non-gps) from low-orbit satellites, and the ambiguity in this method may be resolved either by two passes of the low satellites, or by getting a gps fix from the high-orbit satellites. It is important for people to realize that the positioning error, when SARSAT doesn't get a GPS fix, can be substantial. Many folks don't realize that the high-altitude GPS-using satellites are used in many "SARSAT" rescues.

http://en.wikipedia.org/wiki/Internatio ... _Programme