FBG旁瓣对复用解调的影响及旁瓣抑制方法

摘要

为了解决光纤光栅传感器性能蜕化对复用解调结果的影响,基于光纤布拉格光栅(FBG)应变传感器的解调原理,分析了FBG光栅串联复用时反射谱旁瓣对解调结果的影响.通过理论推导及模拟仿真,发现FBG传感器性能蜕化时存在反射谱的带宽变大、峰值降低以及旁瓣增大等现象.分析了反射谱旁瓣以及链路连接损耗对FBG复用解调结果产生的影响,并针对这个问题,提出了利用浮动解调阈值以及抑制反射谱旁瓣的方法来减少解调结果的出错率.最后,实验证实了相关理论的正确性与方法的可行性,结果表明,利用本文提出的方法可将FBG复用解调结果的出错率由原来的11.36%降低为0,极大地提高了应变测量结果的准确性.%With the aim to resolve the influence of the performance degeneration of FBG sensors on multiplexed demodulation, the affects of reflection sidelobes on the demodulation of a series multiplexing FBG sensor was analyzed based on the demodulation theory of FBG strain sensors. When the performance of the FBG sensors was degenerated, it was found that the bandwidth of the reflection spectrum was broadened, the peak value fell, and the reflection sidelobe was augmented by both theoretical deduction and simulation. The effects of reflection sidelobes and the linkconnected loss on the FBG multiplexed demodulation were analyzed in detail, then the floating demodulation threshold and suppressing reflection sidelobe were presented to resolve the effect and to reduce the error rate of the multiplexing demodulation. Finally, the theory is validated and the method is demonstrated experimentally. Experimental results show that the error rate of the multiplexing demodulation reduces from 11.36% to 0, and the accuracy of the measurement result is greatly improved.