Localization of a broadband source using a matched-mode procedure in the time-frequency domain

In this paper, we present a nonconventional matched-mode procedure for localizing a broadband source in the time-frequency domain. This hybrid coherent and incoherent approach exploits both the temporal and spatial characteristics of the multimode arrival structure at a receiving sensor array. In the previous work, a time-domain technique was developed to deal with narrowband signals coherently. It consists of the following three steps. The first step employs a receiving sensor array to separate the modes by the conventional modal filtering approach. The second step is to estimate the energy and relative arrival times of the various modes which arrive at the receiver. The last step uses the differences of modal travel times to estimate the source range, and uses the ratios of modal energies to estimate the source depth. Here, we employ bandpass filters to divide the received broadband signal into several subfrequency bands, and apply the first and second steps of the previously developed coherent narrowband technique to the subfrequency bands in the time domain. The results obtained from subfrequency bands are then combined incoherently in the frequency domain to produce an estimate of the source position. Numerical simulation of an experiment with explosive sources at the shallow water site of the Yellow Sea is presented.>