Design And Implementation Of Portable Underwater Wireless Electromagnetic Communication System

According to the requirement of sustainable development strategy,people continue to explore new economic area,such as the ocean which contains abundant resources.When divers make underwater operations,it's essential to have a good underwater communication method.Compared with the traditional underwater wireless communication method,the portable underwater wireless communication system based on the conduction current field can realize short distance wireless data transmission.The antenna size is small,and the system is hardly disturbed by the external environment.It has extremely strong confidentiality,and the technology has certain advantages in the field of underwater wireless communication at short range.The paper does the design and realization of portable underwater wireless electromagnetic communication system which has a wide application prospect,and they can be used for diving enthusiasts' and divers' communication,ships and autonomous underwater vehicles,and frogmen forces' coordination.The systems have high reliability and stability.At first,the paper introduces the basic theory of the conducted current field communication and its underwater propagation characteristics.It also indicates the method of enhancing the communication distance,and analyzes the impedance of the electric dipole antenna.Because the frequency of underwater communication is limited for VLF or less,the paper designs the portable underwater analog voice communication system.It needn't signal modulation and demodulation.The voice signal could be directly converted to achieve short-range real-time voice transmission.Secondly the paper states the principle of the DQPSK signal modulation and demodulation technology and synchronous technology.Then the total design and simulation of the hardware system is given,including the design method of each module.The related devices are adjusted on the basis of the index,and the circuit schematic diagrams of each module are given.The paper simulates the hardware circuit by simulation softwares,such as Tina and Multisim.And it finishes the design of the digital core board and the compilation of the software program.The project analyzes the implementation of DQPSK modulation and demodulation technology,and simulates the software module by Modelsim and Signal Tap.Finally,the paper tests every sub-module in the system,gives the results and analysis of testing,and completes the whole system design.A series of laboratory and field tests are accomplished to achieve voice signal transmission,and verifies the correctness and feasibility of the conduction current field communication theory to consummate the research of portable underwater wireless electromagnetic communication technology.