Method and system for locating signal emitters using cross-correlation with a reconstructed waveform

1. A method of determining a location of a signal emitter, the method comprising:

receiving at each of three or more of sensors a received signal corresponding to a signal transmitted by the signal emitter;

processing a first of the received signals received at a first of the sensors to produce a template waveform describing an estimate of the signal transmitted by the signal emitter, the first of the received signals being relatively free of noise, interference, and multipath effects so that a modulation protocol may be recognized, and the first of the received signals can be demodulated;

communicating one of: (1) the template waveform; and (2) information sufficient for reconstructing the template waveform, to second sensors, the template waveform having a lower communication bandwidth requirement compared to the received signal,

wherein processing the first of the received signals to produce the template waveform comprises despreading the received signal and processing the despread signal to produce estimates of symbols used to generate the transmitted signal; the information sufficient for reconstructing the template waveform comprises the estimated symbols, a spreading code for the transmitted signal, and a phase of the spreading code relative to the estimated symbols;

cross-correlating the template waveform with at least three of the received signals received at the sensors;

identifying at least one cross-correlation feature from each cross-correlation; and

using the cross-correlation features to determine the location of the signal emitter.

2. The method of claim 1 , further comprising communicating the received signals from the first sensor and another of the sensors to a common controller, and wherein the common controller selects which of the received signals to process to produce the template waveform, and wherein the common controller produces the template waveform from the selected received signal.

3. The method of claim 1 , wherein the signal transmitted by the signal emitter is produced by digital modulation of a carrier with a digital information signal.

4. The method of claim 1 , wherein processing a first of the received signals received at the first of the sensors to produce the template waveform includes identifying synchronization information and transmitter impairments in the transmitted signal and including the synchronization information and emulating the transmitter impairments in the template waveform.