With a complex wavelet function, a new real-time recursive algorithm of wavelet transform (WT) is analyzed in detail. Compared with the existing recursive algorithm in two directions, the computing time is greatly red...With a complex wavelet function, a new real-time recursive algorithm of wavelet transform (WT) is analyzed in detail. Compared with the existing recursive algorithm in two directions, the computing time is greatly reduced in response to faults signals in power systems, and the same recursive algorithm can be generalized to other wavelet functions. With the phases and magnitudes of complex WT coefficients under the fast recursive algorithm, a method to detect faults signals of power systems is presented. Lastly, the analyzing results of some signals show that it is effective and practical for the complex wavelet and its real-time recursive algorithm to detect faults of power systems.展开更多
针对非负支撑域受限递归逆滤波(NAS-RIF)算法对噪声敏感和耗时长等缺点,提出了一种改进的NASRIF盲复原算法。首先,为了改进原始NAS-RIF算法的抗噪性能和复原效果,引入了一种新的NAS-RIF算法代价函数;其次,为了提高算法的运算效率,结合H...针对非负支撑域受限递归逆滤波(NAS-RIF)算法对噪声敏感和耗时长等缺点,提出了一种改进的NASRIF盲复原算法。首先,为了改进原始NAS-RIF算法的抗噪性能和复原效果,引入了一种新的NAS-RIF算法代价函数;其次,为了提高算法的运算效率,结合Haar小波变换,仅对低频子频带的图像进行NAS-RIF算法复原,而高频子频带的信息,则通过带间预测分别从低频子频带的复原图像中预测得到;最后,为了保证高频信息的准确性,提出了一种基于最小均方误差(MMSE)的带间预测。分别对模拟退化图像和真实图像进行了仿真实验,采用该算法得到的信噪比增益分别为5.221 6 d B和8.103 9 d B。实验结果表明:该算法在保持图像边缘细节的前提下,能够较好地抑制噪声;此外,该算法的运算效率也得到了较大的提高。展开更多
Aiming at mitigating multipath effect in dynamic global positioning system （GPS） satellite navigation applications, an approach based on channel blind equalization and real-time recursive least square （RLS） algori...Aiming at mitigating multipath effect in dynamic global positioning system （GPS） satellite navigation applications, an approach based on channel blind equalization and real-time recursive least square （RLS） algorithm is proposed, which is an application of the wireless communication channel equalization theory to GPS receiver tracking loops. The blind equalization mechanism builds upon the detection of the correlation distortion due to multipath channels; therefore an increase in the number of correlator channels is required compared with conventional GPS receivers. An adaptive estimator based on the real-time RLS algorithm is designed for dynamic estimation of multipath channel response. Then, the code and carrier phase receiver tracking errors are compensated by removing the estimated multipath components from the correlators＇ outputs. To demonstrate the capabilities of the proposed approach, this technique is integrated into a GPS software receiver connected to a navigation satellite signal simulator, thus simulations under controlled dynamic multipath scenarios can be carried out. Simulation results show that in a dynamic and fairly severe multipath environment, the proposed approach achieves simultaneously instantaneous accurate multipath channel estimation and significant multipath tracking errors reduction in both code delay and carrier phase.展开更多
基金Project supported by Guangdong Province Natural Science Foundation and Central China Electric Power Group Co.
文摘With a complex wavelet function, a new real-time recursive algorithm of wavelet transform (WT) is analyzed in detail. Compared with the existing recursive algorithm in two directions, the computing time is greatly reduced in response to faults signals in power systems, and the same recursive algorithm can be generalized to other wavelet functions. With the phases and magnitudes of complex WT coefficients under the fast recursive algorithm, a method to detect faults signals of power systems is presented. Lastly, the analyzing results of some signals show that it is effective and practical for the complex wavelet and its real-time recursive algorithm to detect faults of power systems.
文摘针对非负支撑域受限递归逆滤波(NAS-RIF)算法对噪声敏感和耗时长等缺点,提出了一种改进的NASRIF盲复原算法。首先,为了改进原始NAS-RIF算法的抗噪性能和复原效果,引入了一种新的NAS-RIF算法代价函数;其次,为了提高算法的运算效率,结合Haar小波变换,仅对低频子频带的图像进行NAS-RIF算法复原,而高频子频带的信息,则通过带间预测分别从低频子频带的复原图像中预测得到;最后,为了保证高频信息的准确性,提出了一种基于最小均方误差(MMSE)的带间预测。分别对模拟退化图像和真实图像进行了仿真实验,采用该算法得到的信噪比增益分别为5.221 6 d B和8.103 9 d B。实验结果表明:该算法在保持图像边缘细节的前提下,能够较好地抑制噪声;此外,该算法的运算效率也得到了较大的提高。
基金co-supported by National Natural Science Foundation of China (No. 61101075)the Pre-research Foundation (No. 9140A24040710HK0126)Fundament Research Funds for the Central Universities (YWF-11-02-176)
文摘Aiming at mitigating multipath effect in dynamic global positioning system （GPS） satellite navigation applications, an approach based on channel blind equalization and real-time recursive least square （RLS） algorithm is proposed, which is an application of the wireless communication channel equalization theory to GPS receiver tracking loops. The blind equalization mechanism builds upon the detection of the correlation distortion due to multipath channels; therefore an increase in the number of correlator channels is required compared with conventional GPS receivers. An adaptive estimator based on the real-time RLS algorithm is designed for dynamic estimation of multipath channel response. Then, the code and carrier phase receiver tracking errors are compensated by removing the estimated multipath components from the correlators＇ outputs. To demonstrate the capabilities of the proposed approach, this technique is integrated into a GPS software receiver connected to a navigation satellite signal simulator, thus simulations under controlled dynamic multipath scenarios can be carried out. Simulation results show that in a dynamic and fairly severe multipath environment, the proposed approach achieves simultaneously instantaneous accurate multipath channel estimation and significant multipath tracking errors reduction in both code delay and carrier phase.
