Research On Methods To Improve Long-distance Transmission Performance Of XCTD Channels

The ocean is rich in treasure resources.China is a big marine country with rich marine resources.It is of great significance to strengthen the development of marine resources to enhance China's economic construction.In the measurement of ocean data,the jettison type ocean equipment,the jettison type ocean profiler,has been widely studied.Among them,the expendable conductivity temperature and depth profiling system(XCTD)is a kind of ocean measurement equipment developed in recent years.With the characteristics of low cost,navigation,real-time and large area,it has been widely used in the marine survey market.Although XCTD has been widely studied,the research on the performance of instrument channel transmission is relatively less,which makes the problem of signal affected by the channel in the process of long-distance transmission unclear.Because of the particularity of its channel,it has the characteristics of time-varying and low signal-to-noise ratio,so it is relatively difficult to change its channel structure.And with the increase of detection depth,the amplitude of the signal is greatly attenuated,which is not conducive to signal extraction.At present,many factors will affect the accuracy of hydrological data measurement in the research of abandoned measuring instruments.The transmission channel characteristic of throw away profiler is also a key problem affecting the accuracy of signal transmission.So how to better optimize the transmission channel is the main content of this paper.This paper adopts two research methods to improve the long-distance transmission performance of XCTD,one is to optimize the circuit structure of XCTD channel,the other is to use single carrier frequency division multiple access(SC-FDMA)communication technology to further optimize the signal transmission performance.Firstly,this paper analyzes the structure of XCTD profiler,establishes the circuit model of transmission channel according to the working mode of XCTD and the structural characteristics of channel.In order to better study the compensation mode of XCTD channel,the XCTD channel device is built in the laboratory.By analyzing the influence of channel impedance parameters on the transmission signal,the channel model of XCTD is optimized,and the compensation method is determined The channel mode is 3 H inductor in series with underwater shaft,and the load resistance is 10 M?.On the basis of compensation channel,the matching between SC-FDMA and XCTD channel is analyzed,SC-FDMA algorithm model is built,and SC-FDMA simulation system based on XCTD channel is built with MATLAB software.By comparing the simulation results of DPSK modulation,OFDM system and SC-FDMA technology,it is verified that SC-FDMA technology can reduce the bit error rate of channel to a certain extent for XCTD optimized channel model,and it is in phase Compared with the DPSK modulation model,the BER performance of SC-FDMA simulation system is improved by about 13 d B,and the BER is reduced by 0.09% compared with OFDM system.Therefore,SC-FDMA technology can improve the stability and accuracy of XCTD channel transmission.The research work of this paper has a certain theoretical significance and practical application value for the study of the common problems of the signal transmission performance of the abandoned instrument.