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Originally Posted by Thorn
You can't do it for two reasons: You don't know the power being transmitted, and you don't know what materials and objects are between you and the AP that are attenuting the signal.
In a purely theoretical situation, where you know the power level of the transmitter and where the signal is only lost in free space, then yes, you could measure the distance. It's actually pretty trivial, as it's the same formula used to compute the free space signal loss.
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I totally agree with you that there is no way to accurately calculate the distance of an AP in a real-life situation with so many unknown variables by measuring signal strength.
I wonder, however, if one could at least determine with reasonable accuracy weather the AP is "pretty close" or "really far" - independent of signal strength. With the simple rig based on a really wide parabola I've been playing with, I think that I could measure the distance of of an AP up to perhaps 50 meters in 10 meter units. Now, I don't yet understand many (most?) of the principles behind how this works, so it could just be a fluke.
In my understanding, when the radiation from a small antenna is focused by a parabolic reflector, the focal point would be slightly different depending on the distance of the antenna. In my case, an antenna 10 meters away focuses almost 50 cm closer to the ... apex of the reflector and an antenna 1000 meters away focuses very close to the calculated focal point. I imagine that this same principle allows the brain to determine depth - by analyzing the difference of angles of incoming light to each eye.
Now, this rig is definitely unwieldy and inconvenient, and I have yet to think of a situation in which this would be useful information. Also, we know the range of power most common APs transmit so there is an easier way to accomplish the same goal. Perhaps somebody else may be able to duplicate my results and even find a use for this.
I think this would make a totally awsome science fair experiment.