Source depth estimation in waveguides

In the present paper a high resolution approach of source depth estimation in waveguide has been proposed. The method was based on the mode filtering technique. It was well known that a high resolution estimator can be obtained by designing a vector orthogonal to the target signal component contained in the data vector, such as the maximum entropy method. By using a mode filter, the field sampling data of a vertical array was transformed to a vector which consists of two parts: the eigenfunction of each mode and the modal phase corresponds to the source range. The latter part can be compensated by means of range information extraction proposed in our previous paper [Shang et al., J. Acoust. Soc. Am. Suppl. 1 74, S78 (1983)]. Then the data vector consisting of a finite number of mode eigenfunctions becomes an “almost orthogonal” and can be used to construct a high resolution power processor.