Design And Implementation Of Underground Digital Communication Systems Based On Current Field Theory

The country is rich in mineral resources, mine incident, however, frequent. If we canachieve wireless communication underground and ground, will greatly improve rescueefficiency. At present, China doesn’t have the independent intellectual property rights ofthrough mine emergency rescue communications system. Mine disaster occurred, the otherwired communication is often interrupted, and signal how to penetrate the strata andbidirectional transmission of information is the key bottlenecks technology of mine wirelessemergency communications. The electric dipole antenna, ground-penetrating informationtransmission based on the conduction current field theory is one of the effective methods tosolve the bottleneck problem.This article in the context of analysis of underground communication at home andabroad, the choice of antenna volume design small, small dependence on the environmentbased on the current field theory of communication.First, the introduction of ground-penetrating conduction current field communicationtheory, analysis of signal transmission principle. To establish the mathematical model of thetransmission mode and build the transmission distance, the signal frequency and conductivitysignal transmission based on MATLAB software simulation platform.Then, in a field environment to establish a physical simulation model, discussed theconduction current, transmission distance, electromagnetic interference and noise on thesignal transmission, and observation of the simulation graphics provide optimized parametersfor the follow-up of the system design.Finally, based on the analysis of theoretical studies and simulation software, select anarrow band, high power utilization, resistance to fading, available non-coherentdemodulation of π/4-DQPSK designed as a digital transmission scheme, and designedFPGA-based current filed of underground communication system.Focus on the preparation of a Verilog-based π/4-DQPSK modulation and demodulationprocess, Modulation and demodulation process is achieved through a modular, Convenientprogram to modify and debug; Developed the system hardware platform (including sendingand receiving circuit, the small signal amplification circuit, the power amplification circuit);The addition of a transformer design, so that the impedance of the antenna and thepower amplifier impedance matching is achieved, in order to complete the high-powertransmission signal. The entire communication system from the serial port transceiver, amodem and a D/A and A/D control can be written by software implementation, embodiesthe idea of software radio.