On the integration of through-the-sensor geoacoustic inversion techniques for environmental adaptation schemes in low frequency active sonars

Abstract

The environmental conditions in shallow water areas are known to strongly affect the performances of low frequency active sonars (LFAS). In particular, interactions of the acoustical field with the seabed interface have been identified as being a key factor that is felt to be well understood previously to any environmental adaptation scheme of those sonars. However, the assessment of the geoacoustic properties of the seabed still constitutes a challenging task. Whenever the seabed data bases are of poor quality in a given area, it is obviously of interest that efficient and robust methodologies be applied in order to assess those properties. One proposed approach to carry on that issue consists in applying geoacoustic inversion methodologies that only make use of the acoustical data available onboard an operational sonar, ie. by only using the data acquired along the receiving horizontal towed line-array of the sonar. This approach, known as through-the sensor technique, probes the environment with the sonar itself and in the same conditions of use as those of the sonar. This paper aims at presenting some practical aspects coming out from the processing of several data set of the BASE'04 experiment that are hoped to assess whether that kind of methodology can be applied within the framework of an ASW operational scenario. In particular, inversions of real data sets are presented from which practical inversion strategies (from a priori parametrization of the inverse problem to final end checks) are proposed.