Underwater source detection using a spatial stationarity test

The problem of detecting a source in shallow water is addressed. The comple xity of such a propagation channel makes precise modeling practically impos sible. This lack of accuracy causes a deterioration in the performance of t he optimal detector and motivates the search for suboptimal detectors which are insensitive to uncertainties in the propagation model. A novel, robust detector which measures the degree of spatial stationarity of a received f ield is presented. It exploits the fact that a signal propagating in a boun ded channel induces spatial nonstationarity to a higher degree than mere ba ckground noise. The performance of the proposed detector is evaluated using both simulated data and experimental data collected in the Mediterranean S ea. This performance is compared to those of three other detectors, employi ng different extents of prior information. It is shown that when the propag ation channel is not completely known, as is the case of the experimental d ata, the novel detector outperforms the others in terms of threshold signal -to-noise ratio (SNR). In the presence of environmental mismatch, the thres hold SNR of the novel detector for the experimental data appears 2-5 dB low er than the other detectors. That is, this detector couples good performanc e with robustness to propagation uncertainties. (C) 2001 Acoustical Society of America.