Posted by Adam Quinan on November 17, 2001 at 21:33:37 from 24.114.4.0:
In Reply to: Re: SandA WDMTGTS GPS posted by Peter H on November 17, 2001 at 21:19:14:
Petr H asked
By the way, can a GPS work in reverse? I.e. so that the rest of us can be informed exactly where the user is?
The answer is no, these small hand held devices only receive, they do not transmit. But there are emergency beacons (EPIRBs) that can be picked up by satellites and allow rescue service to home in on the beacon. They are used on long distance yacht racers I think, though I am sure that ships carry them. Similar satellite transmitters would be portable enough to be carried on a vehicle, many long distance truckers in North America have some sort of satellite tracking system. However, I think that they are too heavy for someone to put in a knapsack. Probably better to leave a few patterans or pine cones, or carry a cell (mobile) phone!