You don't even imagine how much interference you can get from one small 50nW transmitter in place where signal is weak - you can interfere with radios in ~100m radius with a bit of luck. Triangulating signal from transmitter like that is quite easy - there are ready systems for this purpose located around bigger cities, and can locate signals instantly (and such systems has existed for 70 years - http://en.wikipedia.org/wiki/Elephant_Cage) so it's illegal and easy to locate