Underwater 3-Dimensional Imaging Method with Co-Located Stationary Acoustic Source and an Acoustic Vector Sensor

We present a novel 3-dimensional (3D) imaging method that uses an acoustic projector and an acoustic vector sensor (AVS) that comprises of a hydrophone and 3-axes particle velocity sensor to sense the acoustic intensity vector at its location. These are mounted on an underwater platform that is stationary to perform 3D underwater imaging. The imaging using AVS is done in a band of low frequencies below 10 KHz which allows for imaging over a long range. The stationary imaging system proposed in this paper offers advantages over a moving system, such as, less system complexity as there is no requirement of moving platform and no flow noise corruption of the received signal. The main objective of this paper is to present a method to use the information received by a stationary AVS receiver for 3D imaging using a novel processing technique based on an LFM transmit pulse waveform. We demonstrate a method to obtain the spatial extent of the insonified object from the scattered echo returns using the proposed processing technique. The feasibility of underwater 3D imaging using a stationary imaging system consisting of an omni directional acoustic projector and an AVS is demonstrated using realistic simulation studies and is supported by analytical derivations.