GPS is needed because with RF, you can only tell when you're headed toward or away, based on whether the signal is getting stronger or weaker. With two antennae you can resolve it to the point that it can tell you the line to walk in, but not backwards or forwards -- though that'll become clear as the signal becomes stronger or weaker. To get the most accurate fix, you need at least three antennae, which is how GPS works, three sattelites pick up on your beacon and communicate with each other to triangulate exact coordinates. Note that putting the antennae too close together will fuzz up the resolution of your path/position, so that instead of a point, you get a circle (that's what it means when they say that GPS is only accurate to within 3 feet or whatever it is today).
Ixa: I suspect that each stick has a unique identifier, and once one stick has given another stick the permission to view its coordinates (probably done through the dock) it can query them from the GPS or whatever database holds it.
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GPS is needed because with RF, you can only tell when you're headed toward or away, based on whether the signal is getting stronger or weaker. With two antennae you can resolve it to the point that it can tell you the line to walk in, but not backwards or forwards -- though that'll become clear as the signal becomes stronger or weaker. To get the most accurate fix, you need at least three antennae, which is how GPS works, three sattelites pick up on your beacon and communicate with each other to triangulate exact coordinates. Note that putting the antennae too close together will fuzz up the resolution of your path/position, so that instead of a point, you get a circle (that's what it means when they say that GPS is only accurate to within 3 feet or whatever it is today).
Ixa: I suspect that each stick has a unique identifier, and once one stick has given another stick the permission to view its coordinates (probably done through the dock) it can query them from the GPS or whatever database holds it.