Experimental investigation of a virtual planar array for MIMO sonar systems

In this paper a way to achieve a virtual two-dimensional planar array for sonar systems using the multiple input multiple output (MIMO) principle is presented. The time delay information of a planar array can be used for imaging sonars and allows the localization of scatterers in three-dimensional space. In a conventional single input multiple output (SIMO) sonar, this would be achieved using a single transmitter and a receiver consisting of a planar array of N² hydrophones, arranged as a rectangular N × N matrix. We show through simulations and experiments how a virtual planar array can be formed using a linear receiver array and linear transmitter array. For this, an experimental MIMO sonar system was constructed with a 32-channel receiver and a 12-channel transmitter, which allowed the realization of a virtual 32 × 12 array. The array design is analyzed through experiment in a harbor basin and through simulations, validating the principle of the virtual planar array. In addition to the experimental investigations, in which only a limited number of transmitter channels are available, further simulations with a 32 × 32 array are performed for further MIMO arrangements to highlight strengths and weaknesses in different application areas.