We present an all-digital demodulation system of interferometric fiber optic sensor based on an improved arctangent-differential-self-multiplying(arctan-DSM)algorithm.The total harmonic distortion(THD)and the light in...We present an all-digital demodulation system of interferometric fiber optic sensor based on an improved arctangent-differential-self-multiplying(arctan-DSM)algorithm.The total harmonic distortion(THD)and the light intensity disturbance(LID)are also suppressed,the same as those in the traditional arctan-DSM algorithm.Moreover,the lowest sampling frequency is also reduced by introducing anti-aliasing filter,so the occupation of the system memory is reduced.The simulations show that the improved algorithm can correctly demodulate cosine signal and chirp signal with lower sampling frequency.展开更多
For expanding the amplitude-frequency response range of the differential cross-phase multiply(DCM)algorithm in theφ-OTDR system,a temporal spline interpolation(TSI)method is proposed to pre-process Rayleigh backscatt...For expanding the amplitude-frequency response range of the differential cross-phase multiply(DCM)algorithm in theφ-OTDR system,a temporal spline interpolation(TSI)method is proposed to pre-process Rayleigh backscattering(RBS)signals.Through the TSI method,the discrete temporal signals characterizing RBS traces are subjected to interpolation,facilitating a reduction in differential approximation errors.This,in turn,establishes a heightened level of precision in phase demodulation,especially relevant across extensive sensing distances.By comparing the recovered time-domain waveforms and the corresponding power spectral densities without and with the TSI,the above improvement effect has been experimentally validated by utilizing the TSI.The results show that,with the TSI,the amplitude-frequency response range of the DCM algorithm is enlarged by 2.78 times,and the new relationship among f_(pulse),f,and D under the root mean square error(RMSE)tolerance less than 0.1 can be expressed as 1.9(D+1)f≤f_(pulse).This contribution underscores a substantial advancement in the capabilities of the DCM algorithm,holding promise for refined performance in optical fiber sensing applications.展开更多
为降低电磁干扰对信号传输的影响,分析了应答器上行链路信号传输过程及其易遭受干扰信号的特点,设计了基于符号最小均方误差(least mean square,LMS)算法的自适应解调方法。为在硬件平台中实现该解调方法,通过仿真计算,确定LMS算法的自...为降低电磁干扰对信号传输的影响,分析了应答器上行链路信号传输过程及其易遭受干扰信号的特点,设计了基于符号最小均方误差(least mean square,LMS)算法的自适应解调方法。为在硬件平台中实现该解调方法,通过仿真计算,确定LMS算法的自适应算法中间变量变化范围,使用截位操作完成权值系数的更新,设置均衡器长度、步长因子、中值滤波系数分别为1、1/64、16,可在不占用过多硬件资源情况下获得良好的解调性能。解调算法在现场可编程门阵列(field programmable gata array,FPGA)上予以验证,实验表明,当信噪比为6 dB时,FPGA中自适应解调误码率为0.000001,在信噪比大于等于6 dB时,实测误码率与仿真分析误码率基本一致;FPGA自适应解调方法在列车不同速度等级下误码率均小于10^(-6)。展开更多
文摘We present an all-digital demodulation system of interferometric fiber optic sensor based on an improved arctangent-differential-self-multiplying(arctan-DSM)algorithm.The total harmonic distortion(THD)and the light intensity disturbance(LID)are also suppressed,the same as those in the traditional arctan-DSM algorithm.Moreover,the lowest sampling frequency is also reduced by introducing anti-aliasing filter,so the occupation of the system memory is reduced.The simulations show that the improved algorithm can correctly demodulate cosine signal and chirp signal with lower sampling frequency.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.62075153,62075151,and 62205237)in part by the Shanxi Provincial Key Research and Development Project(Grant No.202102150101004)+2 种基金in part by the Shanxi Provincial Central Guiding Local Science and Technology Development Fund Project(Grant No.YDZJSX20231A019)in part by National Key Research and Development Program of China(Grant No.2023YFF0715700)in part by Natural Science Foundation for Young Scientists of Shanxi Province(Grant No.20210302124396).
文摘For expanding the amplitude-frequency response range of the differential cross-phase multiply(DCM)algorithm in theφ-OTDR system,a temporal spline interpolation(TSI)method is proposed to pre-process Rayleigh backscattering(RBS)signals.Through the TSI method,the discrete temporal signals characterizing RBS traces are subjected to interpolation,facilitating a reduction in differential approximation errors.This,in turn,establishes a heightened level of precision in phase demodulation,especially relevant across extensive sensing distances.By comparing the recovered time-domain waveforms and the corresponding power spectral densities without and with the TSI,the above improvement effect has been experimentally validated by utilizing the TSI.The results show that,with the TSI,the amplitude-frequency response range of the DCM algorithm is enlarged by 2.78 times,and the new relationship among f_(pulse),f,and D under the root mean square error(RMSE)tolerance less than 0.1 can be expressed as 1.9(D+1)f≤f_(pulse).This contribution underscores a substantial advancement in the capabilities of the DCM algorithm,holding promise for refined performance in optical fiber sensing applications.
