Research On The Hardware Of OFDM Technology Applied To The Wire Line Logging Telemetry

Orthogonal Frequency Division Multiplexing(OFDM)is a kind of signal modulation technique based on digital signal processing technology.It has been widely used in communication,and it is also an important research direction at high-speed wireline logging telemetry.The purpose of this paper is to discuss the solution of wireline logging telemetry system based on the OFDM technology from the perspective of hardware,and do some experiments to verify the solution.As a result of the rapid development of digital electronic technology,Field Program-mable Gate Array(FPGA)has taken place of the traditional logic gate devices and become the most important part of complex electronic system.The wireline logging telemetry system could do the entire process of encoding and modulation by a piece of FPGA,it makes the design,debugging and updating conveniencly.It is also the most brightly and difficultly spot in the research.At first,the paper analyzes the contents of the wireline logging telemetry system,and determines the parameters with the consideration of the characteristics of logging cable.Then this paper do some further study of the implement method with FPGA,including scramble and descramble,Reed-Solomon encode and decode,interleave and deinterleave,QAM modulation and demodulation,and IFFT and FFT,the core of OFDM system.Finally these modules would be simulated by programming or using the logic IP core of FPGA.The result of simulation could make sure that both the modules and the signal process of the system are valid.Synchronization is the key procedure of the communication system.This paper determined the parameters of the training symbol and cyclic prefix at first,and designed an independent module for each one.There are two mainly parts of synchronization,timing synchronization and sampling frequency synchronization,the paper analyzed the theory and algorithmic of them,and made some optimization for the complex synchronization algorithmic specified to FPGA.Designed a hardware architecture and simulated finally.With the results of simulation,it could obtain that the function of coding,modulation and synchronization based on FPGA are valid for the wireline logging telemetry based on OFDM technology.And raised some idea of channel equalization and analog circuit at the same time,it could be used for next step of development.