Demonstration of the large and small sector limits for large vertical array sector focused matched-field processing in a deep water environment

Abstract

Sector focused matched-field processing is a technique that has been developed to stabilize high-resolution estimators against random phase errors and environmental mismatch. This technique produces satisfactory high-resolution matched-field localization over a wider latitude of environments than does conventional high-resolution techniques. Its implementation requires the selection of several parameters such as sector size, shape and dimensionality. In this work, general guidance is given for the use of this technique by establishing the properties of the small and large sector limits. Specifically, it is demonstrated that in the small sector limit, sector focusing behaves like replica correlator processing (robust and low resolution). Whereas, in the large sector limit, sector focusing behaves like reduced maximum-likelihood processing (high resolution, but not as robust). The demonstration is accomplished by plotting signal gain degradation versus three sediment sound-speed parameters. These plots show a small hot spot at the correct environment immersed in very cool surroundings for the conventional high-resolution estimator (mvdr). Whereas, for sector focusing, the plots show a rather wide swath of acceptable environments. In most cases, the technique peaks on the correct environment. [This work was supported by the Office of Naval Research, with technical management provided by the Naval Research Laboratory, Stennis Space Center, MS.]