Sub-bottom synthetic aperture sonar in robust circumstances

In Kanda Bay of Fukuoka of Japan, 2,996 pieces of chemical ammunitions was detected in the exploration until 2012. Therefore, we have developed sub-bottom synthetic aperture sonar for high resolution at low frequency to explore the targets of the deposited layer. Sonar can be mounted on a small ship under the robust circumstances of environment. We have considered next five issues; refraction at the deposited layer, the frequent velocity change due to tide and wave for small ships, also frequent movement of sensors, week signals in the deposited layer, and flexibility in offline processing, and have developed the solutions. We have carried out the detection test of targets buried in the seabed sediments at Kanda Bay in July and September 2012, and we report the processing method and the result in this paper.