Advanced Surveillance Technology for Underwater Security Sonar Systems

Abstract

On the Japanese coasts, there are so many important facilities which can be exposed to the threats of terror attacks. So, we built an acoustic video system, modifying a dual-frequency acoustic camera DIDSON and developing an optimum underwater surveillance method and software. In succession, a 100 kHz-frequency Wharf Installed Security Sonar was developed. Its transmitting beam is variable in width and can be steered up and down depending on the installation environments, making it possible to easily detect targets. Recently, we have developed an effective moving surveillance method employing a Shipboard Installed Security Sonar consisting of three transducers, each with a different frequency (110 kHz, 240 kHz and 455 kHz) and all sharing a receiving array to monitor both far and near fields. In the 110 kHz mode, the sonar can monitor a far distance and wide area. With the embedded software we developed for overlaying aerial photo maps on sonar images, we obtained data useful for further research to develop an effective surveillance method. We are now proceeding with this development while implementing in this system the moving surveillance method employing the acoustic video camera.