红外探测器所成图像存在固有非均匀性缺陷,现有的基于场景的最小均方差(least mean square,LMS)校正算法在对图像进行非均匀性校正时极易引入鬼影,严重限制了校正效果。针对这一瓶颈,本研究以时域门控鬼影抑制技术为基础,创新性地将韦...红外探测器所成图像存在固有非均匀性缺陷,现有的基于场景的最小均方差(least mean square,LMS)校正算法在对图像进行非均匀性校正时极易引入鬼影,严重限制了校正效果。针对这一瓶颈,本研究以时域门控鬼影抑制技术为基础,创新性地将韦伯定律引入红外图像非均匀性校正体系,提出双门控LMS非均匀性校正方法。该方法摒弃了“绝对无鬼影”的理想化数学优化目标,转而以鬼影处于人眼视觉感知阈值之下为核心准则进行校正;构建了全新的“运动终止”目标检测模型以获取可校正像素增量;并通过预判增量校正目标的运动趋势来确定其校正幅度,从而达到各类复杂场景下图像质量和鬼影抑制性能的协同优化。实验结果证明,双门控法可与现有各类基线校正算法灵活叠加部署,具备优异的算法普适性;肉眼观测和各类图像量化指标均显示,相较于传统的时域门控算法,该方法可在不降低鬼影抑制效果的前提下,将校正效率提高最高达60%。展开更多
外辐射源雷达利用直达天线接收的参考信号作为样本滤除目标回波中的杂波,但由于雨、云、树木或其他运动物体等的影响,回波内可能会包含非零频杂波,导致处理后杂波残余较大,影响目标检测。针对上述问题,提出了一种基于杂波识别的扩展最...外辐射源雷达利用直达天线接收的参考信号作为样本滤除目标回波中的杂波,但由于雨、云、树木或其他运动物体等的影响,回波内可能会包含非零频杂波,导致处理后杂波残余较大,影响目标检测。针对上述问题,提出了一种基于杂波识别的扩展最小均方(Least Mean Square,LMS)对消算法。首先利用模糊函数估计杂波的频率和时延分布,构建含频率信息的多个参考信号。再把多个参考信号插入LMS算法中推导了扩展LMS算法,利用扩展LMS算法可以同时对消静、动杂波。扩展LMS算法能降低对消剩余,提高目标的信噪比,仿真分析和实测数据处理验证了算法的有效性。展开更多
A Matrix Inversion Normalized Least Mean Square (MI-NLMS) adaptive beamforming algorithm was developed for smart antenna application. The MI-NLMS which combined the individual good aspects of Sample Matrix Inversion (...A Matrix Inversion Normalized Least Mean Square (MI-NLMS) adaptive beamforming algorithm was developed for smart antenna application. The MI-NLMS which combined the individual good aspects of Sample Matrix Inversion (SMI) and the Normalized Least Mean Square (NLMS) algorithms is described. Simulation results showed that the less complexity MI-NLMS yields 15 dB improvements in interference suppression and 5 dB gain enhancement over LMS algorithm, converges from the initial iteration and achieves 24% BER improvements at cochannel interference equal to 5. For the case of 4-element uniform linear array antenna, MI-NLMS achieved 76% BER reduction over LMS algorithm.展开更多
Adaptive modulation can optimize the spectrum efficiency and system performance with the channel state information achieved by the long-range channel prediction. To avoid re-estimating channel correlation function as ...Adaptive modulation can optimize the spectrum efficiency and system performance with the channel state information achieved by the long-range channel prediction. To avoid re-estimating channel correlation function as the channel stationarity varies and to track the channel adaptively, LMS （Least-Mean-Square） based long-range channel prediction is discussed in the existing literature, but it needs long observation interval to reach the convergence. Given that all OFDM （Orthogonal Frequency Division Multiplexing） subcarriers have the identical time-domain correlation and stationarity during the same time interval, this paper proposed a 2-D LMS based predictor which updates the filter weights in both time and frequency domain. The proposed scheme can effectively decrease the observation intervals and significantly speed up the convergence than the conventional LMS and Parallel LMS （PLMS）. Complexity analysis and simulation results prove that the proposed scheme can improve the BER （Bit Error Rate） performance and spectrum efficiency with negligible complexity increase.展开更多
Based on the good time-frequency localization of the wavelet packet modulation （WPM） system and the analysis of the muhitone （MT） interference, an improved WPM narrow band interference （NBI） rejection system usi...Based on the good time-frequency localization of the wavelet packet modulation （WPM） system and the analysis of the muhitone （MT） interference, an improved WPM narrow band interference （NBI） rejection system using an adaptive least mean square （LMS） algorithm is discussed in this paper. In the WPM interference rejection system, according to the structure of the wavelet packet tree （WFF） and the characteristic of the MT interference, the demodulated WPM signal which contains the interference component is filtered using an adaptive LMS filtering implementation. Theoretical analysis and simulation resuits show that the proposed method improves the bit error rate （BER） performance of the WPM system in the presence of MT interference.展开更多
随着电力电子设备广泛应用于工业生产的各个领域,电网受到谐波污染的问题日益严重,混合有源滤波器(Hybrid Active Power Filter,HAPF)作为一种有效的谐波抑制手段,受到了广泛关注。然而传统谐波电流检测算法需要受到低通滤波器(LPF)性...随着电力电子设备广泛应用于工业生产的各个领域,电网受到谐波污染的问题日益严重,混合有源滤波器(Hybrid Active Power Filter,HAPF)作为一种有效的谐波抑制手段,受到了广泛关注。然而传统谐波电流检测算法需要受到低通滤波器(LPF)性能的制约,导致系统存在谐波检测精度与响应速度之间的矛盾,滤波效果往往受到限制。因此,采用一种基于LMS自适应滤波器的HAPF控制策略,解决了动静态性能无法兼顾的问题。最后设计了一个在输入电压为220 V、额定频率50 Hz、谐波源为三相整流器带可变负载的系统,并利用Matlab/Simulink验证该方案的正确性,研究结果表明,基于LMS自适应滤波器的HAPF控制器滤波效果良好,准确性和实时性较强,能够显著提高系统的控制性能和抗干扰能力,具有广阔的应用前景。展开更多
文摘红外探测器所成图像存在固有非均匀性缺陷,现有的基于场景的最小均方差(least mean square,LMS)校正算法在对图像进行非均匀性校正时极易引入鬼影,严重限制了校正效果。针对这一瓶颈,本研究以时域门控鬼影抑制技术为基础,创新性地将韦伯定律引入红外图像非均匀性校正体系,提出双门控LMS非均匀性校正方法。该方法摒弃了“绝对无鬼影”的理想化数学优化目标,转而以鬼影处于人眼视觉感知阈值之下为核心准则进行校正;构建了全新的“运动终止”目标检测模型以获取可校正像素增量;并通过预判增量校正目标的运动趋势来确定其校正幅度,从而达到各类复杂场景下图像质量和鬼影抑制性能的协同优化。实验结果证明,双门控法可与现有各类基线校正算法灵活叠加部署,具备优异的算法普适性;肉眼观测和各类图像量化指标均显示,相较于传统的时域门控算法,该方法可在不降低鬼影抑制效果的前提下,将校正效率提高最高达60%。
文摘外辐射源雷达利用直达天线接收的参考信号作为样本滤除目标回波中的杂波,但由于雨、云、树木或其他运动物体等的影响,回波内可能会包含非零频杂波,导致处理后杂波残余较大,影响目标检测。针对上述问题,提出了一种基于杂波识别的扩展最小均方(Least Mean Square,LMS)对消算法。首先利用模糊函数估计杂波的频率和时延分布,构建含频率信息的多个参考信号。再把多个参考信号插入LMS算法中推导了扩展LMS算法,利用扩展LMS算法可以同时对消静、动杂波。扩展LMS算法能降低对消剩余,提高目标的信噪比,仿真分析和实测数据处理验证了算法的有效性。
基金Project supported by the IRPA Secretariat, Ministry of Science,Technology and Environment of Malaysia (No. 04-02-02-0029) andthe Zamalah Scheme
文摘A Matrix Inversion Normalized Least Mean Square (MI-NLMS) adaptive beamforming algorithm was developed for smart antenna application. The MI-NLMS which combined the individual good aspects of Sample Matrix Inversion (SMI) and the Normalized Least Mean Square (NLMS) algorithms is described. Simulation results showed that the less complexity MI-NLMS yields 15 dB improvements in interference suppression and 5 dB gain enhancement over LMS algorithm, converges from the initial iteration and achieves 24% BER improvements at cochannel interference equal to 5. For the case of 4-element uniform linear array antenna, MI-NLMS achieved 76% BER reduction over LMS algorithm.
基金Supported by the National Natural Science Foundation of China (No.60496311).
文摘Adaptive modulation can optimize the spectrum efficiency and system performance with the channel state information achieved by the long-range channel prediction. To avoid re-estimating channel correlation function as the channel stationarity varies and to track the channel adaptively, LMS （Least-Mean-Square） based long-range channel prediction is discussed in the existing literature, but it needs long observation interval to reach the convergence. Given that all OFDM （Orthogonal Frequency Division Multiplexing） subcarriers have the identical time-domain correlation and stationarity during the same time interval, this paper proposed a 2-D LMS based predictor which updates the filter weights in both time and frequency domain. The proposed scheme can effectively decrease the observation intervals and significantly speed up the convergence than the conventional LMS and Parallel LMS （PLMS）. Complexity analysis and simulation results prove that the proposed scheme can improve the BER （Bit Error Rate） performance and spectrum efficiency with negligible complexity increase.
基金Supported by the National Natural Science Foundation of China （No. 60532030）.
文摘Based on the good time-frequency localization of the wavelet packet modulation （WPM） system and the analysis of the muhitone （MT） interference, an improved WPM narrow band interference （NBI） rejection system using an adaptive least mean square （LMS） algorithm is discussed in this paper. In the WPM interference rejection system, according to the structure of the wavelet packet tree （WFF） and the characteristic of the MT interference, the demodulated WPM signal which contains the interference component is filtered using an adaptive LMS filtering implementation. Theoretical analysis and simulation resuits show that the proposed method improves the bit error rate （BER） performance of the WPM system in the presence of MT interference.
文摘随着电力电子设备广泛应用于工业生产的各个领域,电网受到谐波污染的问题日益严重,混合有源滤波器(Hybrid Active Power Filter,HAPF)作为一种有效的谐波抑制手段,受到了广泛关注。然而传统谐波电流检测算法需要受到低通滤波器(LPF)性能的制约,导致系统存在谐波检测精度与响应速度之间的矛盾,滤波效果往往受到限制。因此,采用一种基于LMS自适应滤波器的HAPF控制策略,解决了动静态性能无法兼顾的问题。最后设计了一个在输入电压为220 V、额定频率50 Hz、谐波源为三相整流器带可变负载的系统,并利用Matlab/Simulink验证该方案的正确性,研究结果表明,基于LMS自适应滤波器的HAPF控制器滤波效果良好,准确性和实时性较强,能够显著提高系统的控制性能和抗干扰能力,具有广阔的应用前景。
