01-08-2015, 08:23 AM
This is twofolded:
1. To determine your position, the device must be able, to receive GPS signal from at least 3 satelites or a signal from a cellphone network post (to know at least the position of the post).
2. To tell somebody else your position, the device must be able, to send the information, via cell phone network, if available. Some devices can link to satellites for a radio transmission.
If you are in the woods, in the mod, in an avalange or just lying on your own device, satellite link may not work at all and cellphone network may not be available.
This may be interesting for adv travellors: http://www.sarsat.noaa.gov/
I know this from sailing on open sea.
1. To determine your position, the device must be able, to receive GPS signal from at least 3 satelites or a signal from a cellphone network post (to know at least the position of the post).
2. To tell somebody else your position, the device must be able, to send the information, via cell phone network, if available. Some devices can link to satellites for a radio transmission.
If you are in the woods, in the mod, in an avalange or just lying on your own device, satellite link may not work at all and cellphone network may not be available.
This may be interesting for adv travellors: http://www.sarsat.noaa.gov/
I know this from sailing on open sea.