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用于光纤围栏入侵告警的频谱分析快速模式识别 总被引:1,自引:0,他引:1
相位敏感光时域反射计(Ф-OTDR)在光纤围栏等动态传感领域具有重要的应用,快速、有效地对入侵信号分类识别有着十分重要的意义。基于频谱分析提出了一种称为频谱欧氏距离法(EDFS)的快速模式识别方法。该方法通过短时平移差分和短时能量法对Ф-OTDR的解调信号进行提取,确定待分析数据段;对数据段进行归一化和快速傅里叶变换,获得信号的频谱特征;计算信号频谱与预先生成的模板之间的欧氏距离对入侵信号进行分类、识别。采用三种入侵信号对该方法的有效性和实时性进行了实验验证。结果表明,该模式识别方法可以有效识别扰动信号,识别时间小于传统的动态时域规划模式识别方法耗时的1/10。同时,该方法所需训练样本较少,对环境噪声有一定程度的抑制作用。 相似文献
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光纤光栅在金属锈蚀传感中的应用 总被引:6,自引:0,他引:6
介绍了一种基于光纤布拉格光栅(FBG)应变敏感特性的金属锈蚀传感器。该器件由光纤光栅、有预应力的钢弹簧和一些机械部件组合而成。组合后的弹簧处于压缩状态。在弹簧弹力的作用下,光纤光栅的峰值波长增长了3.2 nm。对该器件进行了加速腐蚀实验:将其放入盐酸环境中,逐日监测光纤光栅峰值波长的变化,发现峰值波长逐渐缩短,说明弹簧的弹性系数随着弹簧的锈蚀而逐渐减小。到弹簧锈蚀断裂,整个锈蚀过程持续了1315 h,平均锈蚀速率约5μm/d。实验表明了该传感器在实际应用中的可能性。同时讨论了光纤光栅的温度效应及其他影响其实用性的因素。 相似文献
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A novel scheme is proposed to transform a Gaussian optical pulse to a millimeter-wave (mm-wave) fre-quency modulation pulse by using a Fabry-Perot interferometer (FPI) for radio-over-fiber (ROF) system. It is shown that modulation frequency of mm-wave is determined by the optical path of the Fabry-Perot (F-P) cavity, and amplitude decay time and energy transfer efficiency are related to the reflectivity of the F-P cavity mirror. The effect of pulse train extension on inter-symbol interference is also discussed. 相似文献
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Analysis of dispersion compensation for position-dependence in externally modulated CATV lightwave systems by using chirped fiber grating 总被引:1,自引:0,他引:1
Transmission of amplitude-modulated sub-carrier multi-plexed (AM-SCM) analog optical signals in single modefiber is an important and useful technology. Amplitude-modulation vestigial-sideband (AM-VSB) cable televi-sion (CATV) systems have been widely used all over theworld. Apart from 1310-nm optical CATV technology,1550-nm systems have been used for longer transmis-sion distance and more multiplexed channel numbers[1,2].However, it is found that fiber dispersion, combined withthe self-… 相似文献
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光栅子结构对光纤光栅特性的影响 总被引:17,自引:5,他引:12
用传输矩阵法对具有不同参数的λ/4移相结构,多节λ/4移相结构,有效折射率调制结构,耦合系数调制结构和“缝合”误差结构等五种光栅子结构进行了数值模拟计算,模拟结果解释了作者研制的均匀光纤光栅,相移光纤光栅的传输谱,也验证了其他研究小组发表的实验结果,通过对各种结构的系统研究了,提出了一些新的利用光纤光栅的设想。 相似文献
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A racetrack waveguide resonator filter was fabricated by ion exchange technology in K9 optical glass. The filter responses of the waveguide resonator were measured with two polarized input lightwaves. The polarization-dependent characteristics of the waveguide resonator were analyzed, and the results of effective indices of nTE = 1.5721 and nTM = 1.5548, coupling ratios of rTE = 0.731 and rTM = 0.761, and losses ofαTE = 4.35 dB/cm andαTM = 6.05 dB/cm were obtained for transverse electric (TE) and transverse magnetic (TM) modes, respectively. The causes of large loss and effective index differences between TE and TM modes were discussed. 相似文献
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An erbium-doped fiber (EDF) laser was configured with a fiber grating, a fiber ring resonator, and a saturable absorber by using un-pumped EDF as mode selection element. The laser showed single mode operation with a narrow linewidth of 5 kHz. The mode selection mechanisms of the un-pumped EDF and the ring resonator are theoretically and experimentally analyzed. 相似文献