Improving the Accuracy of Underwater Object Location Determination in the Ultra-Short Baseline Direction Finding Task

Software and hardware systems for recording the underwater environment are necessary for observing the protective zones of water areas, servicing the mechanisms for developing underwater deposits and monitoring the state of offshore structures. The problem of increasing the accuracy of underwater object direction finding in conditions of underwater object detection using hydroacoustic illumination is considered in the article. For solution this problem introducing a time mark and additional modification of the measuring circuit are used. With several hydroacoustic illumination emitters it becomes possible to create a multi-angle underwater vision system that allows establishing not only the exact spatial position of underwater objects in the analyzed water area, but also the size and shape characteristics of these objects. The key task here is the task of synchronizing the registration of signals reflected by objects from different emitters. The paper describes an approach to reduce the error in the direction finding of objects caused by errors in the digitalization of the sensor signal, using the insertion of a special time mark into the signal, resampling, and more accurate synchronization of the start of the probing signal generation and the moments of digitalization of the sensor signal. The results of experimental verification of the described approach using the example of an underwater object direction finding applying stereo sensors oriented in the horizontal and vertical planes with multiple repetition of measurements are presented. It is shown that applying the proposed approach for the example given in the article increases the accuracy of direction finding by more than 8 times.