Acoustic array sensor tracking system

Multichannel acoustic and geophysical experiments have been conducted recently in the Marginal Ice Zone (MIZ) of the eastern Arctic Fram Straits region using a random array of hydrophones deployed from ice floes with radio linked telemetry across apertures of up to 6 km. Accurate relative positions of hydrophone sensors in the array are required for subsequent data processing. A system of hardware and software has been developed to compute and record relative sensor positions and make plots of the sensor field in real time. Off-line processing uses sound speed profile corrections and model based filtering for greatest accuracy. The system consists of 5 reference sensors in the array field, each co-located with a hydrophone, emitting 5 millisecond tone bursts at a unique frequency approximately every fifteen seconds. Signals are telemetered via a radio link to a receiving station where hardware detects pings and computes time delays between all sensors. These delays are acquired every thirty seconds, to compute an approximate set of array element locations and recorded for later processing. Relative location accuracies of 1 m rms can be obtained at ranges up to 5 km.