椭圆拟合算法确定分布式传感系统输出信号相位差

he distributed optical fiber sensor system, based on Mach-Zehnder interferometer structure, achieves alarm and locating by detecting changes in signal phase of sensing optical fiber, when accures perturbation around the sensing area. After briefly introducing the principle of the Mach-Zehnder interferometer fiber optic sensor system, this paper makes use of the algorithm of ellipse fitting to realize the scheme which can detect the outputs phase difference by establishing the mathematical model of the outputs from a 3×3 coupler. The results of processing valid data indicate that the algorithm is precise. There is very important value for the stability of sensing system and the accuracy of alarm.