共查询到19条相似文献,搜索用时 125 毫秒
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一种改进的双通道滤波回声抵消算法——过采样无延迟子带方法 总被引:1,自引:1,他引:0
在强相关大动态范围语音作用下,回声抵消器直接更新上千阶自适应滤波器系数,计算量大、收敛速度慢。采用子带分析与合成的方法能够减少计算量和提高算法的收敛性能,但子带的分析与合成也给线路中引入了信号延迟。提出了一种改进的双通道滤波回声抵消算法,将子带自适应滤波器映射到全频带滤波器,减少了信号的延迟;同时采用双通道滤波器。使系统工作在较小残余回声功率下。仿真结果表明,改进算法在单边会话情况下收敛快.具有较好的回声抵消效果。 相似文献
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《现代电子技术》2020,(3):22-26
声学回声消除(AEC)系统依赖于自适应滤波器的回声路径估计,当麦克风接收的信号存在回声和近端信号时,可能出现模拟回声路径的自适应滤波器发散,导致回声消除性能下降,严重时影响双端通话质量。一个成熟的声学回声消除器应该包含有双端通话检测算法,针对该问题,提出一种准确度高、性能稳定的基于信号包络检测(Env)和归一化互相关(NCC)估计相结合的双端通话检测(DTD)算法。该算法先使用远端信号与麦克风信号的能量包络来判断双端通话是否发生,当包络检测不能准确地判断双端通话时,再使用远端信号与麦克风信号的互相关估计对双端通话进行最终判断,保证双端通话检测的准确性。仿真实验表明,提出的算法可以准确判断双端通话的开始与结束,并且受回声路径变化的影响较小,提升了AEC系统的性能。 相似文献
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空间滤波测速系统中输出信号的基底成分,理论上可以通过差分方法完全消除。但由于由被测物体表面各处散射到光学系统并被探测器接收到的光能量不一致等原因,导致输出信号中仍然有基底成分残留,为信号特别是低频信号的探测带来困难。为了消除差分滤波器输出信号中残留的基底成分,对空间滤波测速仪中的图像传感器型差分滤波器的结构进行了优化设计。列出并分析了图像传感器型差分滤波器的各种可能结构形式,并且选择了几种典型的结构进行了实验。分别在均匀照明和非均匀照明条件下,从功率谱和信噪比两个方面分析了输出信号的质量,为滤波器结构的优化提供了依据。通过对比不同滤波器结构下系统输出信号的质量,得到了一种最为合适的能大大消除输出信号中残留的基底成分的滤波器结构。 相似文献
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分数延迟滤波器广泛用于通信,语音处理,回声消除等。该文基于信号的多分辨空间一般模型,由尺度函数给出最优FIR分数延迟滤波器的设计方法,并进行数值试验证实其有效性。 相似文献
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针对现有语音增强算法面临残留噪声这一问题,结合人耳听觉系统的掩蔽特性,本文提出了一种优化的语音增强算法。算法分为两级,第一级利用MMSE-LSA谱估计法对带噪语音进行降噪处理,经过处理后,带噪语音信号的信噪比得到了提高。然后,针对第一级增强语音信号中的残余噪声利用人耳听觉掩蔽特性掩蔽掉。为此,算法结合人耳听觉掩蔽特性设计了感知增强滤波器,该滤波器能够有效去除第一级增强语音信号中的残留噪声。仿真实验表明,在各种复杂背景噪声以及信噪比环境下,经过本文算法处理后的增强语音信号残留噪声明显减少,算法提升了增强语音的主观感知质量。 相似文献
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《现代电子技术》2019,(7):66-70
针对回声路径的冲激响应时间长,稀疏控制μ律比例归一化最小均方算法(SC-MPNLMS)计算复杂度高的问题,提出一种变步长的频域分块SC-MPNLMS的线性回归,得到估计回声每个频点的自相关,以及估计回声与误差信号的互相关来确定泄漏系数,从而调整全局步长因子对自适应滤波器系数进行变步长矩阵的更新,改善了算法在稳态阶段时步长因子过大的缺点。针对频域分块自适应滤波算法初始收敛速度慢的问题,将滤波器初始权值赋值为稀疏度适中的随机序列。实验结果表明,在回声路径不同的稀疏程度条件下,保持了与SC-MPNLMS算法相近的收敛速度与稳态回声返回损耗增量(ERLE),并且降低了算法复杂度。 相似文献
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Tanrikulu O. Baykal B. Constantinides A.G. Chambers J.A. 《Signal Processing, IEEE Transactions on》1997,45(4):901-912
The residual echo signal characteristics of critically sampled subband acoustic echo cancellers are analyzed. For finite impulse response (FIR) filter banks, the residual echo signal usually has a relatively broad spectral nature around the subband edges. The residual echo signal of power symmetric infinite impulse response (PS-IIR) filter banks, on the other hand, has very narrowband spectral components around the subband edges. These components can be efficiently removed with PS-IIR notch filters that integrate neatly into the filter banks without introducing perceptually noticeable degradation to the near-end speech. This solution has very low computational complexity and does not impinge on the system performance. Simulation studies with recordings from the cockpit of a car, based on a fast QR least-squares adaptive algorithm, demonstrate the potential of this approach for a practical AEC system 相似文献
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This paper presents a low-complexity wavelet transform that utilizes point-symmetric extension at the image tile boundaries. The proposed approach is considered as an alternative to the well-known symmetric signal extension in dealing with the boundary artifacts that manifest when tiles of images are lossy compressed. The new solution developed for odd-length filters preserves the perfect reconstruction property of the filter banks and deals efficiently with blocking artifacts without requiring any post processing technique or additional information from the neighboring tiles. It is shown that point-symmetric extension at the tile boundaries does not need to be applied explicitly, but instead the equivalent boundary filters can be derived. The lifting-based implementation of the filters provides a very simple way of changing filter parameters at the boundaries that suits both hardware and software platforms. 相似文献
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通过鱼雷对潜目标准确识别,实现对目标的精确打击。当前的目标识别算法采用时频特征提取算法,随着海洋背景噪声强度的增大,准确识别概率不高。提出一种采用亮点回波信号自适应波束形成的鱼雷对潜目标识别算法,首先进行了鱼雷对潜攻击声探测亮点回波模型构建,采用级联滤波器进行回波信号降噪处理,对滤波后的输出信号进行自适应波束形成处理,实现信号的特征提取和指向性聚焦,提高目标亮点回波信号的检测性能,实现目标准确识别。仿真结果表明,采用该算法进行鱼雷对潜目标检测识别,准确检测概率高于传统算法,在低信混比下仍具有较好的准确识别率,抗干扰性能较好。 相似文献
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Hermanowicz E. Johansson H. Rojewski M. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2008,55(5):452-456
In this paper, we present a novel complex discrete-time filter. This is a fractionally delaying (FD) Hilbert transform filter (HTF) further called the FD HTF. The filter is based on a pair of rotated variable fractional delay (VFD) filters. It is capable of performing the Hilbertian as well as VFD filtering of the incoming discrete-time signal at the same time. Thus, one can substitute a cascade of the HTF and the VFD filters with an aggregated filter proposed here. The technique is simple to implement. The advantages lie in lower total delay introduced by the compound filter and in a modular structure. The rotated VFD filters in the pair differ only in the value of one parameter - the VFD. The proposed FD HTF can be applied to adaptive quadrature sub-sample estimation of delay. 相似文献
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首先建立了匹配滤波器输出随多普勒频移的变化规律模型。分析得出通过缩短匹配滤波器长度,可减小多普勒频移对压缩输出的影响,采用一组部分相关匹配滤波器对接收回波处理,估计出回波中的多普勒频率,避免了传统方法的计算量大、结构复杂难以实现等缺陷。方法结构简单,能以较高精度对回波中的多普勒频率作出估计,有利于相位编码信号在快速动目标观测方面的应用。 相似文献
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高光谱分辨率激光雷达(High Spectral Resolution Lidar,HSRL)系统利用窄带滤波器将激光雷达回波信号中的大气粒子(云或气溶胶)散射和分子散射成分分开,提升了云或气溶胶光学特性的反演质量。提出了一种基于HSRL探测原理的HSRL回波信号模拟方法,其原理是利用CALIPSO云/气溶胶消光系数产品和数值天气预报数据被用来仿真星载HSRL 532 nm回波信号。两种典型的窄带光谱滤波器:FPI(Fabry-Prot Interferometer)和碘吸收滤波器,作为分子通道滤波器的性能通过仿真的星载HSRL回波信号进行分析。对三种典型:晴空、卷云、气溶胶(两层厚云)的HSRL回波廓线进行详细的敏感分析表明碘分子吸收滤波器的性能明显优于FPI滤波器,其中碘吸收滤波能保持可以忽略不计的相对偏差(4.010-3%),这是由低光学厚度(1.0)的粒子后向散射效应引起的。但是,如果FPI滤波器的粒子后向散射透过率能保持在10-3水平以下,其仍不失为是一个好的选择。 相似文献
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数字波束合成是多目标数字相控阵天线中一个核心处理模块。在采用FPGA 实现波束合成时,由于不同类型滤波器的存在,需要消耗大量DSP48 Slices 资源。根据目标信号具有频分复用的特点,同时考虑相控阵加权与信道化滤波、正交变换滤波的关系,可以将上述两种滤波器合并成一个滤波器,并且置于加权求和模块之后。新的波束合成方法在保持阵列增益不变情况下,使得后置滤波器个数仅仅决定于目标数量而不是阵元数量,从而大大减少FPGA 资源的消耗。论文不仅分析对比了传统方法和滤波器后置方法的DSP48 Slices 资源消耗,还通过方向图和阵列输出SINR 仿真来证明新方法的有效性。 相似文献
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An ATSC DTV receiver with improved robustness to multipath and distributed transmission environments
Wu Y. Xianbin Wang Citta R. Ledoux B. Lafleche S. Caron B. 《Broadcasting, IEEE Transactions on》2004,50(1):32-41
This paper presents the design and implementation of an 8-VSB DTV receiver for indoor and distributed transmission environments. The receiver is designed to handle severe multipath distortion from indoor and Single Frequency Network (SFN) transmission conditions. The architecture of the receiver is first introduced. The adaptive equalizer structure and design are then discussed in detail. A channel-matched filter is employed as a pre-filter such that the signal energies from different echoes are combined optimally and the signal to noise ratio of the equalizer input is maximized. Feedforward and feedback equalizers are used to handle the pre-echo (pre-cursor) and post-echo (post-cursor), respectively. The feedforward filter is designed to minimize the pre-cursors or convert them into post-cursors, while the feedback equalizer is used to eliminate the post-cursors. Initial tap coefficients are computed to speed up the convergence of these two filters based on the channel estimation. Laboratory tests show that the new prototype DTV receiver has very robust performance in multipath environments. 0 dB echoes can be handled with this receiver due to the enhanced design of the equalizer. It can withstand a -10 dB single echo within a -29.5 to +38.5 microsecond range and a 0 dB echo within a 12 microsecond range. 相似文献