The Design Of Acoustic Positioning Signal And Multi-user Detection Circuit

With the increase of the scope and frequency of the human activities in the ocean, andthe growing demand for ocean development, acoustic positioning technology were receivedmore and more attention of foreign and domestic scholars. However, thetraditional acoustic positioning system has some problems, such as layout and calibration ofdifficult, and with the increase of the number of underwater target, the real-time ofpositioning system declines, complexity of equipment increases.For the positioning of test nodes in the underwater distributed test system, the paperconstructed a based on code division multiple access, no anchor node, long baseline locatingmodel which is convenient for layout and calibration. In order to improve extensibility andreal-time of positioning system, to design based on code division multiplexing positioningsignal. And the process of detecting acoustic positioning signal in which gets eachpositioning signal time delay estimation is in the node, so the node can send the time delayestimation directly to the data control center for orientation, which can reduce the storage ofnode signal data, shorten the time by sending positioning data to control center, and improvereal-time of the positioning system.The content of paper mainly include: first, to introduce node acoustic positioningcharacteristics, the system composition, positioning process and localization algorithm;Second, combined with acoustic channel and independent positioning system characteristics,to design based on code division multiple access acoustic positioning signal and the logiccircuit, m sequence was as address by OOK modulation; Finally, the main part of the paperdesigned and realized positioning signal detection algorithm according to characteristics ofthe positioning signal on FPGA, which was first to detect code element and then recognize msequence by correlation; through the comparison the time delay estimation of sequence andcode element, the starting code element of signal has the least error on time delay estimation, so make it as the time delay estimation of the positioning signal.Simulation and experimental results show that the design of positioning signal and thedetection circuit meet the requirements of the system, the nodes can detect positioning signalaccurately in time, and signal time delay estimation error is less than 200 us on the condition.