Development Of Underwater Transmission System Of XCTD Profiling System

XCTD also known as Expendable Conductivity Temperature and Depth System, is aninstrument which was placed in American research project in the1980s and quickly appliedto obtain temperature, salinity of sea in marine scientific research. Because the varietydepth temperature, salinity curve is indispensable in military deepwater instrumentationactivity, underwater communication activity, underwater fish missile activity and surfaceships and aircraft underwater detection. China has increased the XCTD system technicalsupport under the national863high tech project, and obtained encouraging results. As partof the XCTD system, the communication system between probe and ship deservesattention.The development trend of XCTD, system structure and work process were introduced,among it, we focuses on the XCTD underwater communication system. Through thesystem channel and noise distribution curve, It is know that the XCTD communicationwas not rational and need timely put forward a new system to improve its function. Basedon a lot of previous data, a new absolute QPSK non coherent demodulation for XCTDwas proposed. Based on the analysis of absolute QPSK non coherent demodulation,Breakdown the hardware design and finally through the join simulation of Matlab andPSpice, proved the system can be implemented in reality.