Broadband source localization with a single hydrophone

Source localization with vertical arrays in shallow water has been a topic of intense research in the last 20 years. Although horizontal arrays can (and have) been used, vertical arrays are better suited for extracting signal modal structure and thus provide a source-location estimate in range and depth. It is well known that broadband signals have a localization capability superior to that of narrowband signals. One question that remains largely unresolved is whether frequency extent can compensate for the spatial diversity provided by sensor arrays, i.e. at the limit, can a broadband signal be localized with a single sensor? This communication presents theoretical, simulated, and practical evidence that a multipath-delay maximum-likelihood estimator does provide enough signal to background discrimination for localizing a 500 Hz bandwidth signal at 5 km range in a 130 m depth shallow water channel with a single hydrophone. The real data used in this study were collected during the INTIMATE'96 experiment which was conducted off the west of Portugal in June 1996 during an internal tide tomography experiment. A comparison with localization results provided by a direct match between the received and the model-generated arrival patterns is discussed.