bbeque: TRIangulation actually added a third step. If you could find the transmitter from three locations, you could establish a little triangle inside which the transmitter must be located. The BIangulation thing targetted a general area. TRIangulation narrowed it down considerably. I imagine if they had tried QUADrangulation (which, to my knowledge, nobody ever did), they could have found the street corner.
Congratulations on finding Roberto, if you really have - remember that BIangulation isn't nearly as precise as TRIangulation. I dare you to tell who it is! Then, there's Arturo.