SBIR-STTR Award

Acoustic locator beacons operate at frequencies where significant signal attenuation takes place as a result of the absorpllon of acoustic energy by seawater. This puts a hard upper limit on the range of detection for a simple locating receiver. For example, to extend detection from 1.s to 3 nautical miles, about 3q dB more signal energy at the receiver is needed. Soluations for longer range detection must achieve as much gain as cost-effective implementation will allow. UST proposes to investigate systems which provide 20 to 4q dB improvement in the acoustic detection process with a novel and inexpensive array receiver, and to investigate the implementation of this improved receiver in a configuration which lends itself to a variety of operational deployments.

International Distress Pingers and acoustic beacons are installed in flight data recorders and high value test equipment to permit recovery if lost in deep ocean water. These pingers operate at frequencies where significant attenuation takes place as a result of the absorption of acoustic energy by seawater, thus limiting detection range. Phase I of this effort investigated extending this detection range from two aspects: (1) identifying and testing the design characteristics of an improved locator system, and (2) identifying the characteristics of an improved pinger beacon. The design goal was to realize 20 to 30 dB of gain. The resulting Improved Pinger Locator System, proposed for Phase II implementation, achieves its gain by increased hydrophone directivity and improved signal processing. It also includes an automatic detection process and a user-friendly machine interface which will considerably enhance the performance and operability of the locating system. In-water testing during Phase I highlighted several ways in which an improved acoustic beacon could contribute some dBs to the detection process. Pinger redesign to incorporate these improvements is included as part of the Phase II effort.