Amplitude Phase Shift Keying(APSK)is more suitable for the nonlinear channels of Low Earth Orbit(LEO)satellite communication systems compared to Quadrature Amplitude Modulation(QAM).To tackle challenges posed by Direc...Amplitude Phase Shift Keying(APSK)is more suitable for the nonlinear channels of Low Earth Orbit(LEO)satellite communication systems compared to Quadrature Amplitude Modulation(QAM).To tackle challenges posed by Direct Current(DC)interference and high demodulation complexity,we propose an APSK demodulation algorithm based on K-means clustering.Initially,static DC components are calculated and removed from the received APSK signals.Subsequently,the estimated APSK constellation points serve as initial centers for K-means clustering.These centers are refined through the K-means process and act as theoretical APSK constellation points for the Max-Log-MAP demodulation algorithm,effectively eliminating residual DC.We then introduce a low-complexity APSK demodulation algorithm that utilizes the symmetry of constellation points along with the Euclidean distance between DC-eliminated signals and these constellation points to minimize the set of constellation points.Simulation results indicate that for 32-APSK,our proposed demodulation submodule reduces computational complexity to approximately one-third that of the Max-Log-MAP algorithm while improving Bit Error Rate(BER)performance by about 0.23 dB.Furthermore,end-to-end simulation experiments conducted within LEO satellite communication systems demonstrate that our approach not only maintains this complexity advantage but also enhances BER performance by approximately 1.1 dB.展开更多
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
Systematic optimization of the delayed self-heterodyne method for laser frequency noise characterization is investigated across an extensive linewidth range(100 Hz to 10 MHz).By evaluating various fiber lengths,window...Systematic optimization of the delayed self-heterodyne method for laser frequency noise characterization is investigated across an extensive linewidth range(100 Hz to 10 MHz).By evaluating various fiber lengths,window functions,and five demodulation algorithms,we identify a critical trade-off:long fibers enhance sensitivity for narrow-linewidth lasers but exacerbate spectral leakage in broad-linewidth sources.Our findings demonstrate that Hanning and Blackman windows effectively suppress this leakage,ensuring measurement consistency across different delay lengths.Among the evaluated algorithms,the Hilbert transform offers the superior balance of high-frequency accuracy and computational efficiency.Validated under lowpower conditions,this optimized framework provides a robust and power-independent methodology for precise FN analysis,offering significant guidance for high-performance laser development.展开更多
面对喀斯特等复杂地貌强多径衰落环境时,中国数字音频广播(China Digital Radio,CDR)传统的相干解调算法存在误码率抬升与载波同步失锁现象。这个缺陷严重劣化射频信号的物理覆盖效能。针对该技术瓶颈,提出一种基于卷积神经网络(Convolu...面对喀斯特等复杂地貌强多径衰落环境时,中国数字音频广播(China Digital Radio,CDR)传统的相干解调算法存在误码率抬升与载波同步失锁现象。这个缺陷严重劣化射频信号的物理覆盖效能。针对该技术瓶颈,提出一种基于卷积神经网络(Convolutional Neural Network,CNN)与双向长短期记忆(Bidirectional Long Short-Term Memory,BiLSTM)网络级联架构的智能解调算法。级联模型对接收机基带同相正交序列进行高维特征映射与比特流重构。工程实测基带数据集验证结果表明,新型解调机制在极低信噪比与强频率选择性衰落工况下表现优异。相较于经典Viterbi硬判决算法,所提智能算法具有更出色的抗噪增益与泛化健壮性。展开更多
智能变电站对电流量测的精度、带宽及抗扰动性能要求高。围绕光纤电流互感器(Fiber Optic Current Transformer,FOCT)的旋光测量特性,构建由光路稳控布局、偏振扰动补偿、数字解调结构及误差模型融合校准组成的测量链路,并结合实际工程...智能变电站对电流量测的精度、带宽及抗扰动性能要求高。围绕光纤电流互感器(Fiber Optic Current Transformer,FOCT)的旋光测量特性,构建由光路稳控布局、偏振扰动补偿、数字解调结构及误差模型融合校准组成的测量链路,并结合实际工程场景开展对比测试,对5类指标进行量化分析。结果显示,测量序列在动态条件下形成集中分布,为光学式电流感知装置的工程实现提供了参考路径。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 fpulse,f,and D under the root mean square error(RMSE)tolerance less than 0.1 can be expressed as 1.9(D+1)f≤fpulse.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
基金the Key Project of the Chongqing Natural Science Foundation(2022NSCQ-LZX0191)the Key Research Program of Science and Technology of the Chongqing Education Commission(KJZD-K202202402)+1 种基金the Scientific Research Start-up Fund of Chongqing University of Posts and Telecommunications(A2023-62)the Chongqing Natural Science Foundation(cstc2024ycjh-bgzxm003)for their invaluable support in this research。
摘要Amplitude Phase Shift Keying(APSK)is more suitable for the nonlinear channels of Low Earth Orbit(LEO)satellite communication systems compared to Quadrature Amplitude Modulation(QAM).To tackle challenges posed by Direct Current(DC)interference and high demodulation complexity,we propose an APSK demodulation algorithm based on K-means clustering.Initially,static DC components are calculated and removed from the received APSK signals.Subsequently,the estimated APSK constellation points serve as initial centers for K-means clustering.These centers are refined through the K-means process and act as theoretical APSK constellation points for the Max-Log-MAP demodulation algorithm,effectively eliminating residual DC.We then introduce a low-complexity APSK demodulation algorithm that utilizes the symmetry of constellation points along with the Euclidean distance between DC-eliminated signals and these constellation points to minimize the set of constellation points.Simulation results indicate that for 32-APSK,our proposed demodulation submodule reduces computational complexity to approximately one-third that of the Max-Log-MAP algorithm while improving Bit Error Rate(BER)performance by about 0.23 dB.Furthermore,end-to-end simulation experiments conducted within LEO satellite communication systems demonstrate that our approach not only maintains this complexity advantage but also enhances BER performance by approximately 1.1 dB.
摘要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 by the National Key Research Development Program of China(Grant No.2022YFF0713202)the Research Instrument Development Program of the Chinese Academy of Sciences(Grant No.PTYQ2024YZ0005)。
摘要Systematic optimization of the delayed self-heterodyne method for laser frequency noise characterization is investigated across an extensive linewidth range(100 Hz to 10 MHz).By evaluating various fiber lengths,window functions,and five demodulation algorithms,we identify a critical trade-off:long fibers enhance sensitivity for narrow-linewidth lasers but exacerbate spectral leakage in broad-linewidth sources.Our findings demonstrate that Hanning and Blackman windows effectively suppress this leakage,ensuring measurement consistency across different delay lengths.Among the evaluated algorithms,the Hilbert transform offers the superior balance of high-frequency accuracy and computational efficiency.Validated under lowpower conditions,this optimized framework provides a robust and power-independent methodology for precise FN analysis,offering significant guidance for high-performance laser development.
摘要面对喀斯特等复杂地貌强多径衰落环境时,中国数字音频广播(China Digital Radio,CDR)传统的相干解调算法存在误码率抬升与载波同步失锁现象。这个缺陷严重劣化射频信号的物理覆盖效能。针对该技术瓶颈,提出一种基于卷积神经网络(Convolutional Neural Network,CNN)与双向长短期记忆(Bidirectional Long Short-Term Memory,BiLSTM)网络级联架构的智能解调算法。级联模型对接收机基带同相正交序列进行高维特征映射与比特流重构。工程实测基带数据集验证结果表明,新型解调机制在极低信噪比与强频率选择性衰落工况下表现优异。相较于经典Viterbi硬判决算法,所提智能算法具有更出色的抗噪增益与泛化健壮性。
摘要智能变电站对电流量测的精度、带宽及抗扰动性能要求高。围绕光纤电流互感器(Fiber Optic Current Transformer,FOCT)的旋光测量特性,构建由光路稳控布局、偏振扰动补偿、数字解调结构及误差模型融合校准组成的测量链路,并结合实际工程场景开展对比测试,对5类指标进行量化分析。结果显示,测量序列在动态条件下形成集中分布,为光学式电流感知装置的工程实现提供了参考路径。
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).
摘要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 fpulse,f,and D under the root mean square error(RMSE)tolerance less than 0.1 can be expressed as 1.9(D+1)f≤fpulse.This contribution underscores a substantial advancement in the capabilities of the DCM algorithm,holding promise for refined performance in optical fiber sensing applications.