The Research Of Adaptive Channel Equalization Application In Logging Data Transmission

In order to obtain comprehensive and accurate measurement data in petroleum logging system,efficient and reliable well logging data transmission system is needed.However,with the influence of space restriction and strong interference,logging data transmission channel,is not ideal and can not adapt to the transmission of high-speed and long-distance data signals.Therefore,it is very important to study the transmission characteristics of logging data channel with single conductor and metal pipe wall as transmission medium,as well as the logging data channel equalization technology which is suitable for high speed and long-distance transmission.In this thesis,the structure of single core cable is analyzed and modeled,simulation,the rationality of the model is judged by comparing the spectrum characteristic curve after simulate and the spectrum characteristic curve of the actual measurement,and the attenuation of the signal amplitude and the phase offset are increased linearly with the increase of the signal frequency and the transmission distance.Transmission characteristics of the channel based on single-core cable,a non blind adaptive equalization technique is chosen to balance the single core cable channel.The structure of FIR equalizer is selected,the LMS algorithm and RLS algorithm are deduced,and the influence of the algorithm parameters on the performance of the algorithm is obtained through derivation and simulation.Then the LMS equalization Algorithm and the RLS equalization algorithm are used to adaptively balance the single core transmission channel,and their optimal parameters are obtained.The decision mod,ule is designed,finally the simulation results are combined with the bit error rate,and the results show that the LMS algorithm is used to set the algorithm step ?=128 and the equalization effect is the best when the Equalizer series N = 64.For test data,the SER of the single core transmission cable with short grade(3km),intermediate(5km)and long(7km)is less than 10E-7;Finally,the design of the adaptive Equalizer is designed on the FPGA development environment Quartus II,and the design of the algorithm module is considered in the design process.The realization of the equalizer structure,data calibration and intercept,clock cycle calculation and distribution,and simulation in the Modelsim,the results show that the mean square error e(n)of the different lengths of the single core transmission cable is stable and fluctuates around a small numerical value.