Kite-type passive acoustic detection system for underwater small targets

Potential underwater threats from some small intruders may pose a significant risk to security of some important waterside infrastructures, coastal facilities, subsea pipelines and ships by terrorists or hostile forces. Detection and tracking technologies in farther range are required to counter such threats by taking an appropriate response in time. The limitations of active sonar in high cost, negative effects on marine life, low covertness and high reverberation have stimulated researches in passive detection methods. The Kite-type Passive Acoustic Detection System (KPADS) was developed to provide alarms in the area of underwater security and protection against terrorism intruders and threats from the waterside, including unmanned underwater vehicles, small submarines, surface vessels, divers and underwater robots etc. This paper reports on the detection and tracking of stationary noise source and moving targets in Fuxianhu Lake of China. A series of technologies is applied to a passive triangular array of 18 hydrophones in a uniformly-spaced linear arrangement. Experimental results are presented demonstrating the system performance of detection range up to 8000m, tracking better not less than 4000m, bearing accuracy up to 1°, and are verified by GPS ground truth.