Does anyone here work for a wireless service provider? It would be interesting to hear how major sources of interference are identified and dealt with.
And to follow up on what TallGuyShort says, they most likely triangulate just as for amateur radio when looking for transmissions that violate regulations.
Or, come to think of it, if you know the transmitter goes down I-4 everyday, just sit by the side of the road with a receiver and watch signal strength. I-4 can be pretty crowded, but it shouldn't be hard to narrow it down as the signal gets stronger then starts to tail off.
No it isn't - in this case triangulation is the correct technique. Trilateration is when you measure distances. For instance, locating the epicenter of an earthquake is done by comparing the time at which various waves arrive, and making calculations based on the known speeds of those waves. Doing that with the speed of light at terrestrial distances is very tough and will be prone to inaccuracies and large errors. Instead, you measure the angles at which the signal is strongest, and that is triangulation.