Broadband matched-field source localization

A straightforward algorithm for broadband matched-field source localizaton is developed and subsequently applied to experimental data. For the two-receiver case, the algorithm involves correlating modeled and measured cross spectra and summing coherently over frequency. The extension to the multiple-receiver case is to perform the two-receiver algorithm on each pair of hydrophones and sum the complex results coherently. The frequency band over which the summation is made may be chosen to maximize the signal-to-noise ratio. Using an acoustic propagation model based on ray theory to produce modeled cross spectra, the broadband localization scheme is applied to an experimental dataset in which a pseudorandom noise source was towed past a bottom-moored vertical array in a deep-ocean environment. Localization is successful out to the maximum range of 43 km. The effects on the source localization of varying such parameters as the number of phones, bandwidth, and receiver aperture are examined. It is found that matching the autospectra as well as the cross spectra significantly degrades the localization, and that coherent summation over both frequency and phone pairs is superior to incoherent summation.