共查询到20条相似文献,搜索用时 125 毫秒
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依据自适应旁瓣相消原理,着重分析了宽带干扰信号对旁瓣相消性能的影响,针对宽带干扰影响下,主辅天线间的波程差、主辅天线通道频率特性的不一致性以及主天线旁瓣的频率敏感特性等引起的自适应旁瓣相消系统的主辅天线2通道信号的去相关作用,采用了主天线通道均衡和子带自适应相消2种方法改善带宽特性,并通过MATLAB仿真验证,仿真结果表明该两种方法均可明显改善系统的相消性能,达到良好效果。 相似文献
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基于子带TF-GSC麦克风阵列语音增强 总被引:1,自引:0,他引:1
为了加快基于传递函数广义旁瓣相消器的麦克风阵列语音增强系统的收敛速度,将其自适应模块的输入信号分解到子带以进行处理,并将多通道维纳滤波器引入传递函数广义旁瓣相消器的非自适应支路,以便更有效地抑制非相干噪声.实际测试结果表明,相对于基于全带广义旁瓣相消器的麦克风阵列语音增强系统,采用该子带传递函数广义旁瓣相消器结构的语音增强系统具有更高的输出信噪比. 相似文献
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传统滤波器组为降低旁瓣,需要提高滤波器阶数。该文将广义旁瓣相消的思想运用于滤波器组的旁瓣干扰抑制,在滤波器通带外的干扰信号频率处自适应形成零点。基于LMS算法,该文提出了基于自适应旁瓣相消器的滤波器组旁瓣干扰抑制算法,给出了算法的矩阵形式。通过限制系数长度,旁瓣相消器仅仅对消旁瓣大功率干扰信号,而对带内有用信号的影响很小,其作用相当于用一个低阶滤波器实现一个高阶数滤波器的功能,当信号功率较之干扰功率很小时尤其有用。仿真结果显示算法具有良好的旁瓣干扰抑制性能,较之高阶滤波器组大大减少了计算量。 相似文献
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基于外辐射源的雷达系统中可以使用自适应天线旁瓣相消技术以消除直达波和多径杂波的影响。以外辐射源雷达信号处理系统为基础,首先讨论了自适应天线旁瓣相消的原理,结合实时信号处理机的设计,给出了一种基于ADSPTS101sTigerSHARCDSP平台实现自适应天线旁瓣相消的硬件设计方案和软件实现流程。外场实验数据给出的处理结果说明本文方案是有效的。 相似文献
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自适应天线旁瓣相消技术是在天线技术、自适应滤波以及阵列信号处理相结合的基础上发展起来的。利用自适应旁瓣相消系统能够使雷达天线的旁瓣零点自适应的对准干扰的到来方向,最大程度的抑制干扰。同时,还可以大大提高主天线的信干噪比。 相似文献
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文中提出了一种新的多相位子带自适应回声消除系统。在子带内进行自适应滤波对建模长度比较长的脉冲响应特别有效,同时由于仿射投影算法具有预白化的作用,它同样也具有改善滤波器收敛性能的功能。该系统集中了多相子带自适应滤波和仿射投影算法的优点,结合了子带内的双端检测算法,使得系统在临界采样的情况下能进行稳定有效的工作。实验表明:该系统对于语音信号和强相关信号都表现出了良好的性能。 相似文献
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We propose subband adaptive array processing for mitigation of both intersymbol interference (ISI) and cochannel interference (CCI) in digital mobile communications. Subband adaptive array processing employs filter banks in a front end to an adaptive array receiver. By decomposing the signals into a set of subband signals, the analysis filters enhance the correlation of multipath rays in each subband. This enhancement is blind in the sense that no a priori knowledge of the temporal characteristics or spatial signatures of arriving signals is required. With the increased coherence, the desired signal can be effectively equalized by subsequent spatial processing. Further, the CCI signals and their multipaths can be suppressed with fewer degrees of freedom. The effects of quadrature mirror filter and discrete Fourier transform filter banks on multipath correlation are delineated 相似文献
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In this paper, two analytical methods for evaluating the coding efficiency of subband coding are proposed, and optimization of filter coefficients of the perfect reconstruction FIR filter banks is considered, based on a new performance measure called unified coding gain. First, matrix representation of the subband coding in the time domain is considered, and conventional subband filter banks are classified into orthogonal ones such as the QMF and nonorthogonal ones such as the SSKF. For the orthogonal filter banks, the coding gain shown by Jayant and Noll is introduced, and their theoretical performance evaluation is carried out. However, this first method cannot be applied to nonorthogonal filter banks any longer because the coding gain is defined on the assumption of filter orthogonality. Therefore, an optimum bit allocation problem for subband coding is considered, and the unified coding gain, which can be applied to arbitrary subband filter banks, is derived as a new performance measure to take the place of the coding gain. This second method enables us to estimate the coding efficiency of arbitrary transform techniques as well as the subband approaches, and its result suggests that the SSKF(5 × 3) outperforms the QMF as long as the number of subbands is not too large, even though its filter length is much shorter. This result encourages us to find filter coefficients that maximize the unified coding gain according to filter length. In addition, new perfect reconstruction FIR filter banks which have not only low computational complexity but also good energy compaction properties are presented. 相似文献
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Order statistic filter banks 总被引:1,自引:0,他引:1
Filter banks play a major role in multirate signal processing where these have been successfully used in a variety of applications. In the past, filter banks have been developed within the framework of linear filters. It is well known, however, that linear filters may have less than satisfactory performance whenever the underlying processes are non-Gaussian. We introduce the nonlinear class of order statistic (OS) filter banks that exploit the spectral characteristics of the input signal as well as its rank-ordering structure. The attained subband signals provide frequency and rank information in a localized time interval. OS filter banks can lead to significant gains over linear filter banks, particularly when the input signals contain abrupt changes and details, as is common with image and video signals. OS filter banks are formed using traditional linear filter banks as fundamental building blocks. It is shown that OS filter banks subsume linear filter banks and that the latter are obtained by simple linear transformations of the former. To illustrate the properties of OS filter banks, we develop simulations showing that the learning characteristics of the LMS algorithm, which are used to optimize the weight taps of OS filters, can be significantly improved by performing the adaptation in the OS subband domain. 相似文献
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基于子带化的宽带数字波束形成延时补偿新方法 总被引:1,自引:0,他引:1
采用宽带信号的相控阵雷达可获得高的距离分辨率,但也面临挑战:宽带数字波束合成和自适应抗干扰。典型的宽带自适应数字波束合成架构中,首先,在基带采用分数延时滤波器实现多通道的延时补偿;然后,将宽带信号分解为许多子带,在每个子带内做传统的窄带自适应数字波束合成;最后,合成为宽带波束输出。该信号处理方法,在宽带条件下,通过宽带延时补偿实现了精确的波束指向,取得了较好的抗干扰性能。文中基于子带化方法,提出了一种新的架构,将延时补偿合并到窄带波束合成中,即用窄带的附加相移,代替了原有的多通道延时补偿单元。结果是该架构中不再需要分数延时滤波器,大大降低了计算量节约硬件资源。同时,仍然保证了宽带阵列雷达波束的精确指向。结合相控阵雷达阵列实例,文中分别采用传统架构及所提出的新架构完成宽带波束合成,给出仿真结果以供对比,证明了新架构的有效性。 相似文献
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Petraglia M.R. Batalheiro P.B. 《IEEE transactions on circuits and systems. I, Regular papers》2004,51(6):1194-1202
Subband adaptive filtering structures are attractive in applications such as acoustic echo cancellation and channel equalization, due to their properties of decorrelating the input signal and reducing the computational complexity. Recently, a new adaptive filtering structure with critical sampling was proposed. In this paper, we describe an optimization procedure to select the analysis and synthesis filter banks of this new subband structure, so that minimum steady-state mean square error or fastest convergence rate can be achieved. Such filter-bank design method is based on a theoretical analysis of the convergence properties of the adaptation algorithm and uses a nonlinear optimization routine. Computer simulations illustrate the convergence improvements that can be obtained with the filter banks designed by the proposed method. 相似文献
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In this paper, we develop a directional 2-D nonseparable filter bank that can perfectly reconstruct the downsampled subband signals. The filter bank represents two powerful image and video processing tools: directional subband decomposition and perfect reconstruction. The directional filter banks consist of (1) the input signal and the subband signals modulation, (2) diamond shape prefilter, and (3) four different parallelogram shape prefilters. This paper addresses the design and implementation of a two-band filter bank that is proved to be able to provide perfect reconstruction of the downsampled subband signals. Finally, we use a conventional 1-D half-band filter as a prototype and then apply the McClellan transform for the specific 2-D diamond shape and parallelogram shape subfilters. This method is extremely simple in designing the analysis/synthesis subfilters for the filter bank. 相似文献
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The symmetric extension method has been shown to he an efficient way for subband processing of finite-length sequences. This paper presents an extension of this method to general linear-phase perfect-reconstruction filter banks. We derive constraints on the length and symmetry polarity of the permissible filter banks and propose a new design algorithm. In the algorithm, different symmetric sequences are formulated in a unified form based on the circular-symmetry framework. The length constraints in symmetrically extending the input sequence and windowing the subband sequences are investigated. The effect of shifting the input sequence is included. When the algorithm is applied to equal-length filter banks, we explicitly show that symmetric extension methods can always be constructed to replace the circular convolution approach 相似文献
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提出了一种基于滤波器组的单载波频域均衡(FB-FDE)技术的窄带干扰抑制方法,该方法在多径时延较大的地空宽带通信中具有很强的窄带干扰抑制能力。从理论上详细分析了基于滤波器组的窄带干扰抑制技术能够克服基于FFT频域均衡缺点的主要原因,并在此基础上提出了基于自适应子带合并的算法。理论分析和仿真试验均表明,该方法抑制窄带干扰能力强,运算简单,适于工程实现。 相似文献
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自适应滤波器组设计是多速率滤波器组理论和应用的一个重要方面。由于其频率响应更好匹配于输入信号的统计特性,这类滤波器组可获得更大的子带编码增益。该文研究了两带自适应FIR线性相位双正交滤波器组的设计问题,给出了设计算法,特别是通过最优IIR双正交滤波器组确定初始点(初始滤波器组)的方法。仿真结果表明,得到的滤波器组的子带编码增益远远超过了最优的IIR正交滤波器组,与已有的设计结果比较,编码增益明显提高。 相似文献