Design Of Base Band Modulation System Based On OFDM In Mine

China has rich coal resources, which used widely in the industrial production and daily life because of their low prices, let our country become the world's largest consumer and producer. Now, the demand of coal is increased rapidly with the development of economic, whose position in the national economy is self-evident. Underground mining is very dangerous, the accident of coal production is frequently happened, which makes the community much concern, and real-time location and status monitoring is required. Wireless communication technology is essential, especially in recent years, with the development of production management and information technology, as well as more and more needs of bandwidth and intelligent information, the development and application of wireless communication technology in the mine field have great prospects.In this dissertation, the coal mine complex communication environment of wireless communications, the signal in the mine tunnel in the communication and the factors that affect the signal propagation are analyzed. The most important problem of mine wireless communications currently is multi-path fading, whose harmful effects are analyzed, too. The Design of base band modulation system based on OFDM is proposed after a brief introduction to anti-multipath fading technology in mine. Multi-path fading in mine wireless communications is solved by using OFDM anti-multipath fading performance, which improved system performance.Combined with the system design which proposed in this dissertation, the performance index of system simulation is introduced, bandwidth utilization and bit error rate (BER) are analyzed theoretically under several modulations. Then, the parameters of the mine environment is set and simulated by Matlab, QPSK is adopted to modulate and demodulate, the BER curve is obtained by analyzing multi-path fading performance under different conditions, which provided the basis for anti-multipath fading in mine communication. Finally, DSP is adopted to design the base band modulation system, its peripheral hardware circuits are analyzed in detail, OFDM system design plan is proposed and the design task is completed.