利用重叠多光栅的随机非均匀采样来实现动态或静态应变信号传感与解调。给出了基于可调谐滤波器的重叠双光栅解调系统组成及其随机非均匀采样的实现方法,重叠多光栅可在动态应变信号测量时产生时域上的非等间隔传感脉冲,解调系统采用质心法硬件解算,结合平滑滤波方法,可同时满足测量速度与解调精度的需要。实验中通过产生周期随机变化的三角波可调谐滤波器扫描电压来实现重叠多光栅的随机非均匀采样,在重叠双光栅与平均500 Hz可调谐滤波器扫描速率条件下可产生2 kHz随机分布的传感脉冲,最大可实现1.9 kHz的动态应变信号测量,动态应变信号的测量带宽相当于单光栅解调系统的8倍。
Dynamic or static strain sensing and signal demodulation are realized by using random non-uniform sampling of superimposed fiber Bragg gratings (FBGs). Superimposed FBGs demodulating system based on tunable filter and its realization of non-uniform sampling method are presented. The superimposed FBGs are designed to generate non-equidistant space of sensing pulse train in time domain during dynamic strain signals measurement. By combining centroid hardware finding algorithm with smooth filtering method, the demodulation speed and accuracy can be simultaneously kept. Random non-uniform sampling of superimposed FBGs can be realized by generating periodic random variable triangle wave driving voltage of tunable filter. By using superimposed FBGs, a 1.9 kHz dynamic strain is measured by generating an additive non-uniform random distributed 2 kHz optical sensing pulse train at a triangular wave periodically randomly changing scanning voltage with the mean scanning frequency of 500 Hz. The dynamic strain measurement bandwidth is eight times of single FBG interrogation system.