PaulS:
It won't be. The RSSI value will give to "in the same field", "in the same county", "in the same state", and "in the same country" types of values.Anyway, we can't see how you have configured the XBees or what code is running on the Arduinos. So, you really can't expect answers.
Okay. The part of this project is to develop a zoning algorithm from low accuracy data, therefore let's just assume that the RSSI is an acceptable factor for distance measurement.
For the sake of simplicity I am running them both at factory defaults in AT mode.
PC -> XBee Explorer -> XBee Router AT -> Wireless -> XBee Coordinator AT -> PC
There is no Arduino involved at this point. The ONLY change I have made is change the PAN ID on both of the units, the rest is at default. I have two serial consoles open, the XBee's echo as supposed to. Both Explorers have their "RSSI" LED on, which doesn't get any dimmer if I move the modules further away (tried up to 20 meters).
According to the documentation, P0 has to be set to 1 (which it is by default) in order for RSSI pin to be PWM. However I am still getting no PWM, just a solid ~3.3V.