Ray Theory Application in Long Baseline System

The long baseline (LBL) system is widely used to locate and track autonomous underwater vehicles (AUV) through acoustic communication. Three important issues are presented here in LBL system application with AUV. Those issues which regard the normal acoustic communication between LBL system and AUV are the depth of towed array, the length of beacon cable, and the effective area of the AUV. The first issue is the key of the LBL system, which ensures the normal communication between towed array and beacons. The second issue which impacts the normal communication from the AUV to beacons in available range should be considered after the first one has been settled. Then the last issue determines the safe work area of the AUV. The ordinary differential equations (ODE) algorithm of ray is deduced from Snell's law. The ODE algorithm is applied to obtain sound rays from sound source to receiver. These problems are solved by the judgment that whether rays pinging from a sound source arrives at a receiver. The sea trial shows that these methods have much validity and practicality.