Research Of Underwater DC Carrier Communication System Based On Manchester Code

In recent years,more and more ocean observation platforms are developing toward the direction of miniaturization,unmanned,intelligent and clustered.When the platform needs to collect ocean acoustic information,it will have better acoustic detection performance to use the towing mode to cast the acoustic towed body deeper into the sea.However,the weight and volume of the equipment that can be towed by the miniaturized platform are limited,and it is difficult to realize real-time and high-speed information interaction with the outside world for pure submersible equipment.The carrier communication system designed in this paper can effectively solve the problem of power supply and communication when the miniaturized ocean observation platform carries acoustic towed body.This article completes the research and design of DC carrier communication system based on Manchester code using mono-conductor coaxial cable as the transmission medium.Three parts work was mainly completed as follows: Analysis of Coding Technique for carrier communication system,the design of hardware circuit for system and the development of software for system.First of all,several baseband transmission codes are selected as the alternative channel codes of carrier communication system according to the theoretical nature of the system.Through formula derivation and simulation,the bipolar Manchester code is suitable for carrier communication system.The theoretical communication speed that carrier communication system can achieve and the factors that affect the communication error rate are analyzed at the same chapter;After that,the design and research of the hardware circuit of the carrier communication system are completed.The transmission properties of the mono-conductor coaxial cable are obtained by modeling and simulation,and the energy signal multiplexer circuit is designed according to its specificity.The multiplexer circuit includes the energy and signal coupling separation module,the communication signal driver module,the communication signal reception module and the supporting power supply module;Finally,the development of the software module of the carrier communication system is completed.Each software module is based on one Cyclone IV FPGA chip,which can complete the functions of Manchester code encoding and decoding,data form con version and command distribution.After the above work is completed,functional tests and sea tests are carried out.The test results show that the underwater DC carrier communication system based on Manchester code works well and stably,and the parameters of each part meet the design specifications.