DOA estimation of internal waves generated by fluctuating cylinder in stratified medium via array processing

Abstract

The movement of an objective in a stratified medium such as oceans, generates internal waves that propagate with the specific directions. The frequency of the internal waves is very low (0.01–0.008 Hz) and they can spread over long distance (∼50 km). Also, direction-of-arrival (DOA) estimation refers to the process of retrieving the direction information of several electromagnetic waves/sources from the outputs of a number of receiving antennas that form a sensor array. In this theoretical-experimental study using DOA conception, the propagation direction of internal waves induced by a moving objective in a stratified medium is estimated. It can lead to detect moving targets inside of stratified mediums in a passive way with various applications. As a case study, a fluctuating cylinder in the stratified water is utilized to generate internal waves and as well as five fast response salinity sensors are used in a uniform linear array (ULA) arrangement to mine data. In current work, six well-known algorithms Bartlet, MUSIC, WMUSIC, DML, SML and WSF are used to DOA estimation of the generated internal wave. The comparative results show the proper performance of DOA estimation (for the direction of wave propagation) so that estimation errors are insignificant.