TABLE OF CONTENTS In the following we give some examples of the application of space-time adaptive processing to sonar problems. We will address briefly the problem of suppression of reverberation. [1] Secondly we will touch upon matched filed processing techniques which can be used for passive estimation of source parameters. We omit any introduction to sonar principles. For an introduction to sonar fundamentals that reader is referred to the book of Urick [506]. The content of this chapter follows closely a paper by Klemm [249]. All figures have been taken from this publication. The application of space-time filtering for application with active sonar is also addressed by Jaffer [218]. Several articles on spatial array processing in a shallow water sound channel have been published by Klemm [231, 232, 234, 235, 237, 248]. This appendix focuses on the possibilities of space-time processing under the boundary conditions of an acoustic waveguide.
Active sonar, although being an echo technique like radar, differs from radar in several aspects:
The spatial and temporal variability of the ocean normally does not permit coherent processing of coherent pulse trains. The low velocity of sound propagating in water (about 1500 m/s) and the long achievable range (up to several hundreds of kilometers) lead to echo durations of the order of magnitude of minutes. This is much larger than the usual correlation time limited by surface waves and other irregularities of the acoustic channel. In contrast to radar, the Doppler frequency due to a moving target can...
