Design And Implementation Of An Underwater Acoustic Locator System

Underwater acoustic beacons are installed on airplanes to find out the Flight DataRecorder (Black Box) promptly after an airplane’s wreckage on the sea. Once beaconimmersion in water, it transmits sound signals at a given frequency band, so it can be foundout by receivers of the same frequency band. But as beacons’ acoustic source level is lowand operating frequency is high, acoustic energy decays quickly. So general receivers canonly work at a distance for about2km. An beacon’s life is one month generally, so it’snecessary to increase the working distance from receivers to underwater acoustic beacons.This paper firstly introduced underwater acoustic beacons and correlating searchequipments’ performance parameters and the mode of search operation. Judging from this, ademand for improving search efficiency and increasing search distance was advanced. Thenit introduced vector hydrophones and characteristics of underwater acoustic propagation.On the basis of above theories, an underwater acoustic locator system was designed.The system has explained following aspects: Signal adjusting module、 Signalcollecting and transmitting module、Power supply module and Signal processing software.The system enlarges and filters the signals of beacons received by hydrophone, anddoes an analog to digital conversion, then the signal is transmitted through the Ethernettogether with a magnetic compass’s bearing message. The signal processing software makesthe best of the underwater acoustic beacon’s characteristics to improve the detect ability ofsmall-signals, such as sliding FFT, sliding window, energy accumulation and so on, finallylocate the target.At last, some experiment results about the system was given out.