Matched-beam processing: A synthesis of conventional beamforming and matched-field processing

Abstract

Conventional beamforming, based on the concept of delay and sum of plane-wave signals, has been the cornerstone for radar and underwater acoustic array processing for many years. Matched-field processing, which has received much attention in recent years, represents a departure from conventional beamforming in that the signal propagation is an integral part of the processor. In this paper a framework is presented (i.e., matched beam processing) in which conventional beamforming and matched-field processing can be unified and treated on an equal footing. Matched-beam processing is matched-field processing in the beam domain. The resulting benefits are (1) the extension of full field processing to conventional beams, (2) the ability to do spatial filtering based on the angle of arrival, and (3) the ease of integration of the (matched-beam) processor into existing systems. For a horizontal array in shallow water, conventional beamforming would be the processor to use, but it suffers from signal gain degradation and bearing bias when the signal energy is split over many beams. Matched-field processing can be used to estimate the bearing accurately, but it must simultaneously estimate the target range, depth, and bearing. Using matched-beam processing, bearing can be estimated accurately while maintaining some tolerance to environmental mismatch.