How to estimate distance between two android devices? (bluetooth preferred)

Question

Target is not to have the real distance. It is something simpler.
Target is to check whether another device is very very close. True or false. Let\'s say 1

Answer 1

The only feasible way to do it that I can think of is with NFC. To use Bluetooth or Wi-Fi you'd have to do it via signal strength, but every transmitter is different so that wouldn't be reliable at all.

Latency is rather useless since the radio waves travel at the speed of light and the time difference between traveling an inch and a mile is essentially zero. To measure that difference you'd need a much higher resolution than you have in a phone.