How does GPS work? [closed]

GPS technology is used in safety devices to get the alert in an emergency event. How does GPS work with these devices?

Solution 1:

Those devices have to have some kind of GPS receiver which might vary in accuracy and a second channel to actually transmit anything.

GPS is a passive system based on a satellite network. Those satellites "broadcast" their time and as the Receiver picks up their signal it's able to use the time difference to get the distance to the satellites. After that some math magic (geometry) is used to get your position. In addition there are some more details involved like the almanac which tells the Receiver where each satellite should be but those are the basics.

The second channel could be a number of things and depends on the actual device. It might be a GSM module, could be internet connected or use some other kind of wireless transmission depending on the circumstances it's supposed to be used in.