一种光纤振动传感器的改进型相位解调方法研究

Improved phase demodulation method for fiber optic vibration sensor

为消除干涉幅值对分布光纤振动传感系统在相位解调时的影响,提出了一种基于改进型相位生成载波(PGC)调制解调技术的Michelson干涉仪型光纤振动传感解调系统。其首先对Michelson干涉仪光纤振动传感系统的参考光纤上施加一定幅值和频率的高频载波信号,完成对待测振动信号的高频调制。而后通过零次谐波、一次谐波载频信号和低通滤波器还原出含有待测振动信号的正弦项和余弦项。最后通过对正弦项和余弦项的适当变换并相除解调出不含有干涉幅值的待测信号项。通过仿真与实验分析,提出的改进型PGC解调方案可以有效消除干涉幅值对解调输出信号产生的失真影响。

In this work,a Michelson interferometer based sensing demodulation scheme using an improved phase generated carrier(PGC)technique is proposed to eliminate the influence of interference amplitude on the phase demodulation of the distributed optical fiber vibration sensing system.Firstly,a high frequency carrier signal is applied to the reference fiber of the Michelson interferometer based fiber vibration sensing system to modulate the vibration signal which is acts on the sensing fiber link of the sensing system.Second,the sinusoidal and cosine terms of the applied signal can be acquired by the zero order harmonic,the first order harmonic carrier signal and the low-pass filter.Finally,the demodulated signal without the interference amplitude is demodulated by a proper transformation and the division of sine term and cosine term.The simulation results and experimental results show that the improved PGC demodulation technique can effectively eliminate the influence of interference amplitude on the final demodulation output signal.