D类音频功放的可集成Pop-Click噪声抑制系统

设计实现了一种可集成于D类音频功放芯片内部的Pop-Click噪声抑制系统,通过全新的输出级软启动控制以及辅助反馈环路的采用,保证了软启动过程中的环路稳定性和输出驱动级的完整性,实现良好稳定的PopClick噪声抑制。采用0.5μm CMOS工艺实现了集成Pop-Click噪声抑制系统的2.0 W单声道D类音频功放。测试结果显示,在单位增益、8Ω喇叭负载下,该D类音频功放的Pop-Click噪声能被有效抑制至1.5 mV内。     

OFDM系统下脉冲噪声的时频联合抑制方法

本文分析了VHF或较低UHF频段下出现的脉冲噪声对OFDM系统下信号接收的影响.基于Mobile WiMAX的下行链路和Bemouli Gaussian脉冲噪声模型,提出时频二维相结合的脉冲噪声联合抑制算法.仿真结果表明通过联合抑制方法,符号错误率和比特错误概率得到了明显的改善.     

Phase noise floor suppression of the output carrier from double sideband-carrier suppressed modulation system

A theoretical model of all the influencing factors on the phase noise floor of the output carrier from the double sideband-carrier suppressed (DSB-CS) modulation system is presented. Based on the established DSB-CS modulation system with different cases, the phase noise of the input carrier and the output doubled frequency carrier is measured and calculated using the theoretical model, respectively. The calculation results basically agree with the measurement results. It is shown that the phase noise floor ...     

Implementation for noise suppression in images

Random noise in images represents the primary problem for early visual processing. This paper describes an adaptive surface labelling technique (ASL) that suppresses image noise by using data-driven rules that concern surface continuity. The algorithm first obtains a global estimate of the noise distribution and then tries to fit a surface to each part of the image. If this can be done so that the error in fitting a surface is within what would be expected from known noise statistics, then the central pixel is reset to lie on that surface. Analytical results are presented which demonstrate algorithm success provided that the number of samples in the patch is greater than 2m, where m is the number of linear parameters that determine the form of the patch.     

Stereophonic acoustic echo cancellation employing selective-tap adaptive algorithms

Stereophonic acoustic echo cancellation has generated much interest in recent years due to the nonuniqueness and misalignment problems that are caused by the strong interchannel signal coherence. In this paper, we introduce a novel adaptive filtering approach to reduce interchannel coherence which is based on a selective-tap updating procedure. This tap-selection technique is then applied to the normalized least-mean-square, affine projection and recursive least squares algorithms for stereophonic acoustic echo cancellation. Simulation results for the proposed algorithms have shown a significant improvement in convergence rate compared with existing techniques.     

基于EEMD和模糊阈值的去噪方法

为了提高EEMD分解中噪声主导模态的去噪效果,利用模糊隶属度的优势,提出了一种EEMD和模糊阈值相结合的去噪方法。首先用二范数计算各个本征模态函数(IMF)与观测信号的概率密度函数(PDF)之间的相似度,得到噪声主导的IMF;然后对噪声主导的IMF进行模糊阈值处理,以去除IMF中的噪声;最后将所有的IMF重构得到消噪信号。分别采用仿真信号和ECG信号进行去噪实验,结果均表明,所提方法的去噪效果整体上优于小波半软阈值方法和基于EMD的间隔阈值(EMD-IT)方法。     

Clustered and deep echo state networks for signal noise reduction

Machine Learning - Echo State Networks (ESNs) are Recurrent Neural Networks with fixed input and internal (hidden) weights, and adaptable output weights. The hidden part of an ESN can be considered...     

Robust extended multidelay filter and double-talk detector for acoustic echo cancellation

We propose an integrated acoustic echo cancellation solution based on a novel class of efficient and robust adaptive algorithms in the frequency domain, the extended multidelay filter (EMDF). The approach is tailored to very long adaptive filters and highly auto-correlated input signals as they arise in wideband full-duplex audio applications. The EMDF algorithm allows an attractive tradeoff between the well-known multidelay filter and the recursive least-squares algorithm. It exhibits fast convergence, superior tracking capabilities of the signal statistics, and very low delay. The low computational complexity of the conventional frequency-domain adaptive algorithms can be maintained thanks to efficient fast realizations. We also show how this approach can be combined efficiently with a suitable double-talk detector (DTD). We consider a corresponding extension of a recently proposed DTD based on a normalized cross-correlation vector whose performance was shown to be superior compared to other DTDs based on the cross-correlation coefficient. Since the resulting DTD also has an EMDF structure it is easy to implement, and the fast realization also carries over to the DTD scheme. Moreover, as the robustness issue during double talk is particularly crucial for fast-converging algorithms, we apply the concept of robust statistics into our extended frequency-domain approach. Due to the robust generalization of the cost function leading to a so-called M-estimator, the algorithms become inherently less sensitive to outliers, i.e., short bursts that may be caused by inevitable detection failures of a DTD. The proposed structure is also well suited for an efficient generalization to the multichannel case.     

基于声回波抵消两路算法的改进更新逻辑

声回波抵消两路算法被广泛用来检测系统双向通话;基于声回波抵消两路算法,提出了一种改进的控制更新逻辑。此更新逻辑通过比较滤波器的回波返回损失(ERLE),判断是否对滤波器进行更新。此改进更新逻辑能正确检测系统双向通话,避免滤波器的错误更新,并提高两路算法的收敛速度,减小存储器资源和计算量。仿真结果证实了此更新逻辑的有效性。     

抑制温度信号噪声方法的研究

在空间相机中,温度传感器输出的信号易受到噪声的干扰从而造成有用信号的淹没,因此研究适用于温度信号的噪声抑制方法具有重要的实用价值.本文对干扰温度信号的噪声来源进行了综合分析,并针对温度信号所含噪声的特点,采用中值滤波法和小波阈值滤波的复合数字滤波算法相结合,对温度信号进行滤波,实现了信噪分离的目的,提高了信噪比,并通过MATLAB的仿真功能对输出的信号进行验证.仿真表明,这两种方法的混合使用对温度信号的噪声的抑制有明显的效果.     

基于跨维度协同注意力机制的单通道语音增强方法

近年来,卷积神经网络在语音增强任务中得到了广泛的应用.然而,目前广泛使用的跳跃连接机制在特征信息传输时会引入噪声成分,从而不可避免地降低了去噪性能;除此之外,普遍使用的固定形状的卷积核在处理各种声纹信息时效率低下,基于上述考虑,提出了一种跨维度协同注意力机制和形变卷积模块的端到端编-解码器网络CADNet. 具体来说,在跳跃连接中引入跨维度协同注意力模块,进一步提高信息控制能力. 并且在每个标准卷积层之后引入形变卷积层,从而更好地匹配声纹的自然特征. 在TIMIT公开数据集上进行的实验验证了所提出的方法在语音质量和可懂度的评价指标方面的有效性.

     

采用噪声预测的迭代单载波频域均衡

采用噪声预测的单载波频域均衡结构,按照Turbo均衡的思想,提出了一种对噪声预测过程进行迭代的迭代单载波频域均衡的方法,并且分析设计了系统迭代均衡时的关键参数。仿真结果表明：基于迭代思想的噪声预测的单载波频域均衡系统在频率选择性衰落信道下具有良好的误比特性能,并且具有较低的复杂度。     

信号点自适应生长算法和图像脉冲噪声的抑制

针对脉冲噪声的抑制问题,提出了一种利用图像中未被污染的信号点向外自适应生长来消噪的快速自适应算法。算法首先利用信号阈值判决区间提取出输入图像中未被污染的信号点形成信号矩阵并作标记,同时计算信号密度;然后利用信号密度自适应控制信号点按一定幅度向外生长;最后对生长后的信号矩阵进行归一化处理和修正,得到滤波结果。与当前消噪算法相比,所提出的算法在消噪效果和复杂度方面优势较为明显。     

Improved variable step-size NLMS adaptive filtering algorithm for acoustic echo cancellation

Acoustic echo canceller (AEC) is used in communication and teleconferencing systems to reduce undesirable echoes resulting from the coupling between the loudspeaker and the microphone. In this paper, we propose an improved variable step-size normalized least mean square (VSS-NLMS) algorithm for acoustic echo cancellation applications based on adaptive filtering. The steady-state error of the NLMS algorithm with a fixed step-size (FSS-NLMS) is very large for a non-stationary input. Variable step-size (VSS) algorithms can be used to decrease this error. The proposed algorithm, named MESVSS-NLMS (mean error sigmoid VSS-NLMS), combines the generalized sigmoid variable step-size NLMS (GSVSS-NLMS) with the ratio of the estimation error to the mean history of the estimation error values. It is shown from single-talk and double-talk scenarios using speech signals from TIMIT database that the proposed algorithm achieves a better performance, more than 3 dB of attenuation in the misalignment evaluation compared to GSVSS-NLMS, non-parametric VSS-NLMS (NPVSS-NLMS) and standard NLMS algorithms for a non-stationary input in noisy environments.     

具有双方对讲保护的自适应回波消除新算法

基于电话会议的声学回波中的双方对讲情况,本文提出了一个无需设置双方对讲检测器,但仍能在双讲过程中保护自适应滤波器消除性能的NLMS类算法.由于可以由远端信号和近端混合接收信号之间的相关性系数的变化来判断双讲发生或回波路径改变,所以改进的算法中直接将其代入滤波器权系数的迭代公式中,从而控制滤波器系数更新的快慢.仿真结果表明与同类算法相比,采用更小的计算量,该算法在双方对讲时能较好地起到保护作用,而在回波路径改变时也具有快速的跟踪性能.     

Measurement of vorticity in the surface layer using an acoustic echo sounder array

The earth's atmospheric surface layer is usually defined as that region of the lower atmosphere (generally below about 10 m above the earth's surface) where surface friction causes vertical fluxes of heat, moisture and momentum to be constant with height. Within the surface layer, either in response to surface friction or to the atmosphere above, horizontal circular eddies often develop. These circular motions may provide the source of rotation for dust devils so often seen on hot and dry days particularly in desert regions. Also, at larger scales ($\text{～ 1 km in diameter}$) regions of warm and therefore buoyant upward moving air, called thermal plumes, may acquire rotation. These plumes may extend from the earth's surface to more than a kilometer in height on a warm afternoon. Fluid dynamicists quantify this horizontal rotation with a parameter known as the vertical component of vorticity. Vorticity is very difficult to measure in the earth's atmosphere at scales of close to a kilometer because the calculation involves wind-speed differences over horizontal distances of about 500 m. The winds must be measured quite accurately because the differences can be quite small and, therefore, the errors in these measurements are often quite large. This work describes a method of measuring vertical vorticity at scales down to 500 m using an array of three acoustic sounders about 2 m above the earth's surface which overcomes some of the accuracy problems mentioned above. We relate these vorticity measurements to other atmospheric parameters and compute temporal spectra of these quantities to help explain the relationship between vorticity, thermal plume activity, and the smaller-scale dust devils.     

Real-time speech enhancement algorithm for transient noise suppression

Multimedia Tools and Applications - To effectively restrain stationary noise and transient noise, a real-time single-channel speech enhancement algorithm is proposed. First, to evaluate stationary...     

基于小波域DCT变换的杂波抑制方法*

针对复杂背景中微弱运动目标检测困难的问题,提出了一种基于小波域DCT变换的背景杂波抑制方法。该方法根据背景杂波和运动目标的不同频率特性,采用低频小波子带频域滤波的方法得到有效抑制背景杂波的残差图像,从而达到抑制背景杂波的目的。该方法首先对原始图像进行小波变换,接着对低频小波子带进行二维DCT变换,再用高斯低通滤波器对DCT变换结果进行滤波,然后对滤波结果进行IDCT变换,最后对滤波前后的低频小波子带作差分处理,对差分结果进行小波逆变换。实验结果表明,该方法处理后得到的残差图像呈现出很好的高斯性和独立性,并     

隧道磁电阻传感器的噪声抑制设计与测试

针对隧道磁电阻传感器拥有很高的灵敏度却存在本底噪声过大的问题,设计了三轴线性隧道磁电阻传感器的探头电路、调制电路、低噪声放大电路。基于商用数字锁相放大器,对调制放大后的输出信号进行解调处理。经实验测试,系统三轴的噪声频谱密度在1 Hz处分别为0. 426,0. 497,0. 513n T/■,较传感器本底噪声有了明显降低。实验结果表明:系统的设计对噪声的抑制起到了一定的作用,适用于一般传感器的降噪处理。