Research On Improving Transmission Performance Of Deep Sea Abandoned Profiler Based On OFDM

Deep sea is rich in mineral resources,biological and other natural resources,as a maritime country,the development of deep-sea resources and the acquisition of deep-sea hydrological data for the future of our country's economic construction and the military maritime powers strategic will has the vital significance.XCTD is referred to as the deep-sea Expendable Conductivity Temperature Depth Profiling System,and it is a cost-effective type of marine detect equipment that abroad in recent years to develop,Because it has the characteristics of navigation,real time,large area,low cost and high precision measurement,since the advent,it has been highly concerned by the oceanologist and researchers.Considering the reasons such as weight,cost,complicated marine environment and so on,the transmission line of channel of XCTD uses a double-stranded enameled wire.and the channel of XCTD is time-varying,low-pass narrow-band and low signal-to-noise ratio.currently XCTD channel mainly uses ASK,DPSK single carrier transmission.but when the signal transmission rate is improved in the traditional single carrier transmission mode,the signal amplitude will be greatly reduced.In a certain transmission frequency,with the increase of the detection depth,the amplitude attenuation of the signal is greater.Therefore,limited by channel conditions,the main purpose of the study is how to improve the transmission performance of XCTD channel while making full use of the limited bandwidth resources.This paper firstly optimizes the circuit channel model of XCTD,then the channel characteristics of XCTD are analyzed.and then the superiority of orthogonal frequency division multiplexing technique for the XCTD transmission is proposed.then the simulation circuit model of XCTD channel is built on the Simulink platform.and then the simulation system model of OFDM is built based on the simulation circuit model of XCTD channel.the simulation results of OFDM is compared in detail with the single carrier modulation mode such as ASK and DPSK.it is verified that the OFDM technology ensures low error rate while improving the transmission rate of XCTD signals.finally,the OFDM simulation system is optimized by using RS coding and over sampling technique,the feasibility and effectiveness of OFDM technology to improve the transmission performance of XCTD channel are further proved by simulation results.and it provides a new way to improve the transmission performance of XCTD channel.