基于M-Z干涉结构的低频信号相位解调方法

Phase demodulation method of low frequency signal based on M-Z interference structure

针对采用马赫-曾德尔(M-Z)干涉结构在低频信号解调时存在静态工作点不稳定和信号失真等问题,提出了一种基于M-Z干涉结构的低频信号解调方法。对干涉型检波系统相位调制的同时进行相位补偿,并对通过引入直流滤波器对传统相位生成载波方法进行了改进,应用软件仿真确定了最佳调制深度,搭建解调系统进行了低频声波信号的频率与幅度测试实验。实验结果表明:该方法可以成功解调出幅度为2.5 rad、频率为0.1 Hz的低频信号,20 Hz的信号频率的线性度高达0.9995。

Aiming at the problems of static working point instability and signal distortion when using Mach-Zehnder(M-Z)interference structure in low frequency signal demodulation,a low frequency signal demodulation method based on M-Z interference structure is proposed.Phase compensation is carried out while phase modulation of interferometric detection system,and the traditional phase generation carrier method is improved by introducing direct-current filter.The optimal modulation depth is determined by software simulation,and the demodulation system is built to test the frequency and amplitude of low-frequency acoustic signals.The experimental results show that this method can successfully demodulate the low frequency signal with amplitude of 2.5 rad and frequency of 0.1 Hz,and the linearity of the signal frequency of 20 Hz is as high as 0.9995.