Question : How well can I establish distance between two Bluetooth devices

I would like to use Bluetooth to establish the distance between two devices to tell if a device is within 2 feet or beyond 2 feet independent of a body being between the two devices.  Is this possible, and what approach could be taken? What might be the resolution possible?  I have seen solutions that are based on signal strength, and also time of flight.  Thanks!

Answer : How well can I establish distance between two Bluetooth devices

If your measurements were calibrated between known devices I would say yes, but if they are unknown devices then no... because not all bluetooth devices have uniform output.  Like all electromagnetic radiation, its strength varies inversely with the square of the distance, so signal-strength:distance will be an exponential, not linear, relationship... ergo if it's not a known value you cannot count on signal-strength telling you anything (accurate) about the distance.