Echo detection enhancement using multiple guide sources in shallow water

The use of a guide source has been proposed as a way of compensating for multipath by forming a spatial-temporal cross correlation of the received target and guide source signals across a vertical array in the frequency domain [Siderius et al., J. Acoust. Soc. Am. 102, 3439–3449]. This processing has the effect of creating a virtual receiver at the guide source position. In general, the performance of a virtual receiver degrades if the spatial integration is not carried out over the span of the array with significant signal. In our study, we have pursued an alternative approach of using guide sources which does not require this integration in general. The guide source signal is simply used as a matched filter. Although this does not correspond to a virtual receiver, it is useful as a means of improving active or passive detection of signals in noise. In general, the signal gain using this alternative technique is dependent on the guide source position. To compensate for this, we construct a separable-kernel-receiver filter bank using multiple randomly positioned guide source signals. Improvement of ROC curves in both passive and active scenarios is obtained using experimental and simulated data. [Work sponsored by ONR.]