Using Genetic Algorithm to Improve the Performance of Sigma-Delta Converter Used on Earthquake Monitoring Systems

Abstract

An earthquake monitoring system consists of many electronic devices, one of this vital device is the digitizer which converts the analogue signal coming from the seismometer (sensor) to digital signal. The Digitizer consists of three main modules, the first module is front-end, the second module is the analog to digital converter using the oversampling technique with the decimation filter, finally the packetization module. This paper will focus on improving the performance of Sigma-delta converter which is used in the digitizer. Genetic algorithm will find the optimum coefficients value of cascaded integrators with distributed feedback Sigma-delta to maximize the signal to noise ratio and the effective number of bits. In addition, this paper will include the steps of choosing the best oversampling ratio and the best order of Sigma-delta. The final design will be implemented on an FPGA kit. As a result of this paper the third order sigma-delta is selected, and in addition, the signal to noise ratio and the effective number of bits are improved to 156 dB, 25.63 bits respectively. The operating frequency of the selected order sigma-delta is 125. 412MHz on FPGA kit.