Design And Implementation Of Through-the-Earth Communication System Transmitter For Mine Based On The Current Field

China has abundant mine resources, but it is a mine accident-prone country. Traditional wired communication has its limitations. In the event of an emergency, wired communication systems are usually destroyed. Contact and location of rescue workers and trapped difficult to achieve, resulting in casualties and property losses. The rescue workers are difficult to contact with the trapped workers. Electromagnetic communication is based on the conduction current field theory, communication process will not be affected by the mine disaster, so it is considered as a more effective means of emergency communication. This paper studied the conduction current field theory and built the simulation model, on this basis the design and implementation of current field through the earth communication transmission system of mine were completed.The main contents and work of this paper are as follows:(1) The conduction current field theory is introduced, the mathematical model of the conductive medium conduction current field is established, the propagation characteristics of conduction current field are analyzed, and the influence of the conductive medium parameters and frequency on the communication distance is studied.(2) Regarding current field through the earth communication transmission system of mine modulation mode the theoretical analysis and simulation is performed in this thesis. This design uses the communication modulation mode π /4-DQPSK and adds channel coding,completes the software code written in the FPGA.(3) Digital circuit design is completed, and the PCB circuit is simulated. The simulation results of the system according to the layout of the circuit traces be optimized to ensure the reliability of the system.(4) A reliable high-power transmitter output circuit which can be work a long time is completed. The signal output is differential,and the circuit parameters is simulated for optimization.(5) In order to improve the emission power electric dipole antenna, the theoretical method of antenna impedance matching is discussed. After analysis and comparison, choose a suitable impedance matching circuit, and complete the related circuit design work.(6) On the basis of the above theory, this paper completed the design and implementation of current field through the earth communication transmission system of mine,and measured the prototype of current field through the earth communication transmission system of mine in laboratory and field. Finally according to the experimental data to analyze problems of the prototype, put forward measures for further improvement.