Precision tracking systems for sonobuoys

A system has been developed to track arrays consisting of several sonobuoys deployed for acoustic detection. This navigation technique can be used to track the position of any free-drifting hydrophones. The method, employing bottom-moored acoustic transponders, can provide relative hydrophone positions to within 20 meters. Ultimate geographical positioning is dependent on the accuracy of the primary navigation system available; satellite navigation can yield absolute positions to within 200 meters. The system operates in real time, yielding a hydrophone fix every 20-30 seconds. Sonobuoy arrays have been deployed for acoustic detection and localization of microearthquakes in the median valley of the Mid-Atlantic Ridge.