The mismatch between echo and replica caused by underwater moving target(UMT)'s radial velocity degrades the detection performance of the matched filter(MF)for the linear frequency modulation(LFM)signal.By using t...The mismatch between echo and replica caused by underwater moving target(UMT)'s radial velocity degrades the detection performance of the matched filter(MF)for the linear frequency modulation(LFM)signal.By using the focusing property of fractional Fourier transform(FRFT)to that signal,a detection algorithm for UMT's LFM echo based on the discrete fractional Fourier transform(DFRFT)is proposed.This algorithm is less affected by the target's radial velocity compared with the other MF detection algorithm utilizing zero radial velocity replica(ZRVR),and the mathematical relation between the output peak positions of these two algorithms exists in the case of existence of target echo.The algorithm can also estimate the target distance by using this relation.The simulation and experiment show that this algorithm'sdetection performance is better than or equivalent to that of the other MF algorithm utilizing ZRVR for the LFM echo of UMT with unknown radial velocity under reverberation noise background.展开更多
In this paper, it presents a data mining model based on Discrete Fourier Transform (DFT)theory for relia-bility data of communication networks, it helps us analyze aberrance data information and provide a method to an...In this paper, it presents a data mining model based on Discrete Fourier Transform (DFT)theory for relia-bility data of communication networks, it helps us analyze aberrance data information and provide a method to analy-sis and evaluate reliability data for management of communication network. It's effective and convenient by a practicalapplication.展开更多
工频同步相量是支撑电力系统分析、保护和稳定控制的基本信息,不同场景对其估计精度与速度要求日益严格。短路故障初期,工频分量、衰减直流分量(decaying DC component,DDC)以及谐波之间频域混叠,导致工频相量准确估计面临严峻挑战。针...工频同步相量是支撑电力系统分析、保护和稳定控制的基本信息,不同场景对其估计精度与速度要求日益严格。短路故障初期,工频分量、衰减直流分量(decaying DC component,DDC)以及谐波之间频域混叠,导致工频相量准确估计面临严峻挑战。针对多种干扰影响相量测量精度问题,提出一种基于改进离散傅里叶变换的强鲁棒性相量估计算法。首先,对DDC误差原理进行分析,利用多个1/4波离散傅里叶变换(discrete Fourier transform,DFT)计算频域误差,同时引入放大乘子以提升算法鲁棒性;然后,在改进DFT基础上提出算法计算量精简方法,将算法计算效率提升近一倍;最后,构建二次谐波陷波滤波器配合所提算法,弥补了二次谐波难以滤除的缺陷。算例测试表明,所提算法不受DDC参数与采样频率限制,并在多种干扰下表现出良好的抗干扰能力,同时有效缩短了相量估计的暂态时间。展开更多
基金Sponsored by National Nature Science Foundation of China(60472101)
文摘The mismatch between echo and replica caused by underwater moving target(UMT)'s radial velocity degrades the detection performance of the matched filter(MF)for the linear frequency modulation(LFM)signal.By using the focusing property of fractional Fourier transform(FRFT)to that signal,a detection algorithm for UMT's LFM echo based on the discrete fractional Fourier transform(DFRFT)is proposed.This algorithm is less affected by the target's radial velocity compared with the other MF detection algorithm utilizing zero radial velocity replica(ZRVR),and the mathematical relation between the output peak positions of these two algorithms exists in the case of existence of target echo.The algorithm can also estimate the target distance by using this relation.The simulation and experiment show that this algorithm'sdetection performance is better than or equivalent to that of the other MF algorithm utilizing ZRVR for the LFM echo of UMT with unknown radial velocity under reverberation noise background.
文摘In this paper, it presents a data mining model based on Discrete Fourier Transform (DFT)theory for relia-bility data of communication networks, it helps us analyze aberrance data information and provide a method to analy-sis and evaluate reliability data for management of communication network. It's effective and convenient by a practicalapplication.
文摘工频同步相量是支撑电力系统分析、保护和稳定控制的基本信息,不同场景对其估计精度与速度要求日益严格。短路故障初期,工频分量、衰减直流分量(decaying DC component,DDC)以及谐波之间频域混叠,导致工频相量准确估计面临严峻挑战。针对多种干扰影响相量测量精度问题,提出一种基于改进离散傅里叶变换的强鲁棒性相量估计算法。首先,对DDC误差原理进行分析,利用多个1/4波离散傅里叶变换(discrete Fourier transform,DFT)计算频域误差,同时引入放大乘子以提升算法鲁棒性;然后,在改进DFT基础上提出算法计算量精简方法,将算法计算效率提升近一倍;最后,构建二次谐波陷波滤波器配合所提算法,弥补了二次谐波难以滤除的缺陷。算例测试表明,所提算法不受DDC参数与采样频率限制,并在多种干扰下表现出良好的抗干扰能力,同时有效缩短了相量估计的暂态时间。
