A simple quasi-distributed fiber sensing interrogation system based on random speckles is proposed for weak fiber Bragg gratings (WFBGs) in this work. Without using tunable lasers or spectrometers, a piece of multimode fiber is applied to interrogate the WFBGs relying on the wavelength sensitivity of speckles. Instead of the CCD sensor, an InGaAs quadrant detector serves as the receiver to capture the fast-changing speckle patterns. A supervised deep learning algorithm of the multilayer perceptron architecture is implemented to process speckle data and to interrogate temperature changes or dynamic strains. The proposed demodulation system is experimentally demonstrated for WFBGs with 0.1% reflectivity. The experimental results demonstrate that the new system is capable of measuring temperature change with an accuracy of 1°C and achieving dynamic frequency of 100 Hz. This speckle-based interrogation system paves a new way for distributed WFBGs sensing with a simple design.

针对基于相位敏感光时域反射计的分布式光纤传感系统的信号识别实时性和准确性问题，提出一种基于小波包分解和支持向量机的信号识别方法。通过小波包分解提取信号的能量特征向量并分析不同信号的平均能量分布趋势。采用支持向量机对敲击、晃动、行走和噪声四种信号共800个实验样本进行训练和识别，识别效果由精确率、召回率、F1值和准确率四种评估指标进行评价。实验结果显示敲击信号和晃动信号的识别精确率、召回率和F1值分别为94.12%、96%、95.05%；95.92%、94%、94.95%；行走信号和噪声信号的识别精确率、召回率和F1值均为100%；总体识别准确率在97%以上。该方法提高了相位敏感光时域反射系统在信号识别时的准确性和实时性。

针对光纤光栅应变传感器测量桥梁结构应变的准确性问题，提出一种原位校准方法。采用等强度悬臂梁模拟桥梁结构，以砝码为激励源，以电阻应变片作为参考传感器，以光纤光栅应变传感器作为被校准传感器，将这两个传感器安装在靠近的位置进行测量和比对。由于不同传感器特征有差异，被校准传感器的测值序列与参考值序列通常存在数据错位，导致无法判断传感器应变响应的一致性。为此，基于动态时间规整算法的数据序列匹配方法，对电阻应变片和光纤光栅应变传感器的应变数据进行了匹配分析，其数据的匹配率在96%以上。此外，还对数据序列进行了跳点的剔除，避免了突变干扰等因素的影响。结果表明，该方法有效解决了传感器的应变响应是否具有一致性的问题，可以实现光纤光栅应变传感器的原位校准，原位校准结果与静态标定结果基本相同。