基于新型相位载波调制解调技术的双 M-Z 光纤振动传感器

摘要

针对分布式振动传感中温度、应力等缓变因素导致的低频相位漂移，提出了一种基于新型相位载波（PGC ）调制解调技术的双M-Z干涉仪型FDDS ，原始信号经窄带模拟低通滤波后，再通过A桙D转换器转变为数字信号完成解调，解决了传统数字PGC调制解调技术中因高速A桙D采集而引入的窄带数字低通滤波的设计难题，通过构造特殊解调项实现了高次谐波解调，同时补偿了因长距离传感光纤引起的相位延时，提高了信噪比，最终达到抑制低频相位漂移、减小定位误差、提高定位精度的目的。%It is found that the phase drift induced by slow time -varying fluctuation such as temperature variation causes the location errors of FDDS .A phase drift insensitive Mach-Zehnder interferometer (M-Z) based on fiber-optic distributed disturbance sensor (FDDS ) incorporating a novel phase generation carrier (PGC) technique is proposed and investigated .By means of a novel PGC technique ,a narrow band analog low pass filter is designed ,it solved the problem of facilitating the digital narrow band low pass filter in high speed A/D acquisition .Meanwhile ,a special demodulation signal was designed to demodulate higher-order harmon-ic ,compensated the time delay of the long optical fiber and enhanced the SNR .Finally low -frequency phase drift can be inhibited ,the location error be reduced and the location accuracy be enhanced .