Hologram formation by using vertical antenna in a shallow water waveguide

Abstract

Holographic signal processing method by using a vertical linear antenna in shallow water is presented in the paper. Offered method of moving source sound field hologram formation by using vertical antenna is based on holographic signal processing of each element of vertical antenna. Sound field of source moving in shallow water waveguide creates a stable interference pattern (interferogram) in the frequency-time domain on each element of vertical antenna. The 2D-FT (2D Fourier transform) of the interferogram is antenna element hologram (AEH). AEH allows to coherently accumulate the sound intensity of the interferogram in a relatively small area as focal spots for each element of antenna. It is shown that the focal spots coordinates on AEH depends upon the source range, velocity, and motion direction. The focal spots coordinates on AEH are same for each element of antenna. The output antenna hologram is formed by superposition AEH. Relationship between focal spot coordinates on the antenna hologram and the source range, velocity, and motion direction are derived in the paper. The results of the numerical experiment of antenna hologram formation for low-frequency (100200 Hz) sound field of source moving in shallow water are presented. The results presented in the paper significantly expand the efficiency of interferometric signal processing in shallow water. [This study was supported by RFBR 19-29-06075, МК-6144.2021.4, and МК-4846.2022.4.]