The Detection and Classification of Broadband Signals in Reverberant Dispersive Environments

The use of broadband waveforms has been suggested as a means of improving active sonar performance against slow moving or stationary targets in littoral waters. In principle, the use of a wide spectrum permits the design of waveforms with nearly ideal "thumbtack-like" ambiguity functions. However, the ocean has dispersive characteristics in both time and frequency that can prevent the idealized broadband gains from being realized. These dispersive effects or coherence losses result in nonidealized signal-echo cross-ambiguity function properties. At present, it is not well understood how coherence losses affect the cross-ambiguity function. The objectives of this paper are to investigate the study and quantify the effects of coherence loss on detection in reverberation-limited environments and provide insight into the maximum tolerable coherence losses and optimum sonar receiver design