| Popis: |
Passive shallow water narrow‐band systems may be designed to locate a known source, or to detect and track an unknown source in shallow water. An experiment was done in 66‐ft deep shallow water off Mission Beach, CA with signals recorded at eight sensors in a vertical line array. A 3‐kHz cw source was moved in a predetermined manner to simulate a target at various ranges and depths. Analysis has been completed on the first question. From the available data, good localizations can be made at ranges out to at least four times the water depth. The second problem (detecting and tracking an unknown target) is, of course, more difficult and only a preliminary report can be given at this time. Because of many dimensions in the problem (e.g., correlation versus range, depth, and time), it seems necessary to calculate sequential probability ratios for all tracks consistent with target motion characteristics. This is a variation of the old “track before detect” philosophy used in active sonar systems. Several examples will be shown where a likelihood ratio is calculated as a function of target range and depth. |
