Transmission System Based On The Seismic Data The Ofdm Synchronization Technology Research And Realization

Seismic exploration is an important method to search for petroleum, the way of exploration through worker causing crustalshock, then sensors sensing the seismic wave to identify geological structure. It consists of geological data gathering, data processing and data interpretation. However data gathering is the most important step in the process of petroleum exploration, which is the precondition of processing and interpretation. As the advance of sensor, its precision improved incessantly, the gathering channels and the transferred data will be required more and more, however, in the mountains, marshes, waters and so on, where is difficult to dispose cable,and inaccessible to arrange sensors, there will be caused a lot of difficulties in the project, so the current cable transmission technique should be changed. Therefore, it is very important to realize wireless transmission of seismic data and real-time monitoring the situation of field, which is a critical method to achieve high quality data. OFDM (Orthogonal Frequency Division Multiplexing), its primary characteristics are high utility ratio of the frequency spectrum, flexibility in modulation, high speed of data transmission, anti-interference, particularly suitable for long-distance transmission and rugger terrain transmission.This design is based on IEEE802.16d standards, research on OFDM physical layer communication theory, then apply it to seismic data transmission system. Because of the OFDM system is sensitive to synchronization errors, so the focus of this paper is how to realize the synchronization of OFDM system effectively and improve system performance.In the first chapter of this paper describes the current status of seismic exploration, compare the current data gathering and transfer systems, and make the OFDM technology can be applied to it to solve the bottleneck of Seismic exploration; The second chapter as an overview of OFDM system, focuses on the principle of OFDM and its structure, then make a detailed analysis of the radio channel and IEEE802.16d protocol, finally, describes the parts of OFDM system, which is based on IEEE802.16d protocol; The third chapter gives a detailed analysis of the effect on system performance, which caused by carrier shift, the deviation of sampling value interval and the error of symbol timing,then give corresponding synchronization algorithms, after analysis and comparison of various algorithms, put forward the synchronization algorithms of this design; The fourth chapter as a core of this paper, have a detailed description of the realization on frame (symbol) synchronization and carrier synchronization of the OFDM system, and give the improved algorithm; The fifth chapter is simulation of the entire system based on Simulink, and analyse the corresponding results, then make the system realized by hardware.