A Study of Detecting and Imaging Small Targets On Seabed

Abstract

The most effective approach to detect underwater targets is to use the sound wave. The reason for this is that the propagating absorption of sound wave in water is much smaller than the other kinds of waves, and a greater working distance can be reached. The problems faced with detecting the small targets on seabed, are fully different from that in detecting underwater target for the general purpose. First, because of the small size of targets, the target strength is small and received echo amplitudes are unlikely great. Second, to decide the presence of small targets and classify them, both the azimuth and range resolution are required to be high for a system. Third, it perhaps is the most important that the main background is the bottom reverberation. All of these imply that there are some particularities in detecting and imaging small targets on seabed. The purpose of this paper is to present such a kind of system. The signal to reverberation ratio and the reverberation to noise ratio related to detecting small targets on seabed, beamforming and focusing in the near field, signal processing and display technique are discussed. Some experiments have been done on lake with the developed system and the obtained results are satisfactory.