In order to keep out underwater intruders at coastal facilities, it is necessary to develop a constant underwater monitoring system with surveillance sonar. For the purpose of usability, it is important to develop the system to be independent of the observers' expertise in interpreting sonar. However, despite the growing number of studies about sonar ADT in recent years, very few readily available studies exist that refer to actual underwater signal characteristics. This paper proposes a practical high-performance underwater constant surveillance system which even inexpert operators can manipulate. The authors developed a new surveillance system which uses three techniques: (1) a signal detection algorithm using an interferometric method; (2) an adaptive dual-threshold detection mechanism for unstable target signal fluctuation; and (3) a track-reliability evaluation system for sustainable tracking using an improved joint-probability data association (JPDA). The authors evaluated the proposed system using a simulation and the experimental data generated from it, and confirmed that the proposed ADT performs better than the conventional method.
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