Single‐frequency matched‐field processing with a single hydrophone.

The most common formulation of matched‐field processing (MFP) involves a single frequency and an array of hydrophones. Since arrays are difficult to deploy (especially vertical arrays), single‐hydrophone MFP methods might prove to be of great practical value. Broadband MFP methods of this type have been developed by Frazer and Pecholcs [J. Acoust. Soc. Am. 88, 995–1102 (1990)]. Single‐frequency, single‐hydrophone localization is possible by synthetic aperture if the source is in steady motion (the receiver may also be moving). By working in the frequency domain, less computational effort is required for constructing replica fields, and it is possible to focus on individual spectral lines of a source to window out interference from other sources and noise. Furthermore, it is possible to localize in three dimensions by taking advantage of environmental complexity.