ICA 2010 paper

Critical issues in the development of high-resolution 3-D sonar systems are the cost of hardware associated with the large number of sensors composing the planar array and the computational burden of processing in real-time the signals gathered. In this paper, such problems are overcome by the optimized synthesis of an aperiodic sparse array and the efficient processing of the acquired signals carried out in the frequency domain and based on Chirp Zeta Transform (CZT) beamforming. On the one hand, the synthesized sparse array enables the device to operate at frequencies yielding an acceptable side-lobe level and a good tradeoff between the sector of view and the resolution. On the other hand, the CZT beamforming, specifically devised to cope with the requirements of volumetric sonar imaging, allows the processing of wideband signals collected by a planar array and generated by a scene encompassing both near-field and far-field regions. The combination of a very limited number of sensors with the CZT beamforming generates a computational load that is two orders of magnitude lower than that of the delay-and-sum beamforming and one order of magnitude lower than that of the traditional frequency-domain implementation. The reduction of the number of sensors and the computational load produces, in turn, a noticeable reduction of the hardware cost.