Experimental comparison of bearing estimation techniques for short passive towed sonar arrays

Experimental comparison of bearing estimation techniques for short passive towed sonar arrays

Colin, M.E.G.D.
Groen, J.
Quesson, B.A.J.
TNO Fysisch en Elektronisch Laboratorium

2004

Although Low Frequency Active Sonar (LFAS) is considered one of the best means of detection and localization of a submarine in shallow water, the use of an active system is not always possible for tactical reasons. It is therefore interesting to include a passive mode in these systems by using the receiving array as a passive array. However, those arrays are smaller than conventional passive towed arrays and the frequencies used for passive submarine detection are lower than the LFAS frequencies, resulting in reduced bearing resolution and accuracy compared to dedicated passive systems. Several signal processing techniques have been studied to improve the performance of such systems in terms of bearing localization. The Extended Towed Array Measurement (ETAM) algorithm is a Synthetic Aperture technique based on the correlation of data snapshots on overlapping hydrophones. It creates a virtual longer aperture that offers better bearing resolution power than a conventional technique. Another widely considered approach is the Minimum Variance Distortionless Response beamformer (MVDR). We have implemented both algorithms and applied them to simulated as well as experimental data sets. In this paper, several passive experiments that were part of a larger Netherlands trial devoted to multistatic Low Frequency Active Sonar (LFAS) are analyzed. The receiving array aperture was 24 m. A target submarine was fitted with a broadband low frequency projector transmitting five intermittent tonals in the 500 Hz-700 Hz band. The bearing estimation accuracy and beamforming gain of MVDR, ETAM and of the conventional beamformer are measured on this data set and compared. © 2004 IEEE.

Sonar
Algorithms
Arrays
Hydrophones
Natural frequencies
Parameter estimation
Signal processing
Submarines
Extended towed array measurement (ETAM)
Low frequency active sonar (LFAS)
Shallow waters
Sonar arrays
Synthetic aperture sonar

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Conference Proceedings Ocean '04 - MTS/IEEE Techno-Ocean '04: Bridges across the Oceans , 9-12 November 2004 , Kobe, Japan, 2, 608-612

conference paper