Abstract:
During the next several years the U.S. Navy will be installing large-area O (1500 km[sup 2]) shallow-water training ranges off the U.S. mainland. These ranges require underwater acoustic tracking of targets to an accuracy of 100 m. Tracking will be performed via high-frequency (10--50 kHz) pingers located on the targets and bottom-mounted hydrophones (nodes). Traditional multilateral techniques, which require detection and decoding of the track ping at a minimum of three nodes, is not cost feasible. This is due to the limited propagation distance and the large number of nodes required. Another problem is potential damage to the nodes due to fishing operations. Recent experimentation has focused on unique solutions to these problems. These include bearing determination from a single node with a minimum number of sensors O(4) and concrete and steel underwater horns. The influence of the acoustic propagation and SNR on these systems is actively being investigated. Considerable high-frequency propagation data sets in shallow water have been collected and are being analyzed. The systems installed and the data collected will be described. Results of on-going analysis will be presented. Results point to a cost feasible engineering design which satisfies the Navy's needs.