The copy/DF approach to signal-specific emitter location

A general approach for performing signal-specific superresolution direction finding (DF) of cochannel emitter waveforms is reported. This approach, referred to as the copy/DF approach, uses the signal copy vectors provided by a blind or nonblind signal extraction algorithm to construct a spatial spectrum for each signal captured by a narrowband antenna array, where each spectrum has a global maximum in the direction of the signal captured by that copy vector. The approach can be used with any signal extraction algorithm, and is particularly effective in environments containing strong cochannel interference. Two classes of techniques are presented: ARMA-like (autoregressive moving average) techniques, which form spatial spectra with zeroes in the direction of the received interferers and poles in the directions of the copied signals; and ML-like (maximum likelihood) techniques, which approximate the nonblind maximum-likelihood estimate of the direction-of-arrival of the copied emitter waveforms