The present invention relates to emitter location. More specifically, it relates to locating emitters using only their fundamental frequency information. The presentinvention recites a method of determining the location of an emitter source comprising the steps of receiving signal information from the source at a plurality of sensors; and simultaneously processing a large bandwidth, and all received signal information using the fundamental RF frequency that lay within the detection bandwidth, and simultaneously determining the relative time of arrival, of all detected signals, using their relative post FFT fundamental detected phases, and using analysis of these relative instantaneous phases to determine all signal source directions within the detected bandwidth. The present invention also recites an apparatus comprising: a first sensor; at least one other sensor located remotely from the first sensor; a central processor connected to the first sensor and each of said other sensors for receiving signal information from each sensor relating to an emitter source and for determining location of emitter sources using their fundamental RF frequency and the technique above.