Ultra-Short Baseline Acoustic Tracking System

This paper describes an ultra-short baseline Sonar Tracking System that tracks cooperative point-source targets at ranges of up to 10,000 yards. The system operates in two basic modes: (1) Surface ship tracking a target (2) Surface ship tracking a fish which, in turn, tracks the target. The second mode of operation is used whenever the first mode cannot operate because of acoustic conditions, as in long-range tracking of near-surface targets. The ultra-short baseline sonar tracking system requires that the platform to which the sonar transducer is mounted, be stabilized (i.e., any motion of the sonar transducer must be compensated for). This is accomplished on the surface ship by the use of a gyro. The towed fish platform is stabilized via a novel strapdown inertial navigation system which uses an acoustic reference frame requiring small and relatively inexpensive transducers.