脉冲噪声检测与滤除器

从信号的自相关角度出发,分析了信号受脉冲噪声污染的特点.根据信号受脉冲噪声污染的特点,提出了一种从幅度上检测脉冲噪声、从宽度上识别脉冲噪声的方法,然后对检测出的噪声点进行预测插值去噪处理.由于只对噪声污染点处理,未改变非污染信号点,从而极大地保护了信号的细节信息.该滤波器算法简单、能够自动适应信号变化和脉冲噪声特性.实验结果表明,与中值滤波器、均值滤波器相比,该滤波器能够在保护信号细节信息的同时,很好地去除脉冲噪声.     

Impulse Noise Detector Performance Measure Based on Intensity Volume

An accurate detector performance evaluation method provides a fair comparison platform and can also support in parameter optimization for existing Impulse noise detectors in the applications of medical imaging. The Impulse noise detector performance measure (INDPM) package is widely applied as tools for quantitative comparison among detectors, which contains recall measure, accuracy measure, precision measure, specificity measure and F-measure. However, these five measures suffer from limited accuracy in correctly evaluating the performance of a detector and are not in well agreement with human subjective evaluation. To solve this problem, five new measures are proposed by introducing a new concept of intensity volume to form a new Impulse noise detector performance package (IV-INDPM). Using a standard image dataset, we conduct experimental and comparative tests with 32 different original images and 5 different existing detectors. Results demonstrate the superior performance of each new measure within IV-INDPM in reaching a much closer agreement with human subjective evaluation, compared to existing measures in INDPM. Even though five new measures are efficient in evaluating detectors’ performance from different perspectives, a new benchmark algorithm (IND-BA) is proposed as a robust and overall metric for ease of general-purpose use by making the most of these five new measures. Comparison results demonstrate its efficiency and accuracy.     

A Contrast Enhancement-Based Filter for Removal of Random Valued Impulse Noise

This letter presents a new filtering scheme based on contrast enhancement within the filtering window for removing the random valued impulse noise. The application of a nonlinear function for increasing the difference between a noise-free and noisy pixels results in efficient detection of noisy pixels. As the performance of a filtering system, in general, depends on the number of iterations used, an effective stopping criterion based on noisy image characteristics to determine the number of iterations is also proposed. Extensive simulation results exhibit that the proposed method significantly outperforms many other well-known techniques.      

基于分数低阶统计量的盲多用户检测算法

多用户检测算法是抑制CDMA系统中多址干扰的重要手段,但广泛存在的非高斯信道噪声会降低以往的基于高斯噪声模型假设的算法性能.本文采用α稳定分布作为噪声模型,提出了基于分数低阶统计量的盲多用户检测算法,并对该算法进行了理论分析.仿真和分析表明,该算法具有很好的韧性,同时适用于高斯噪声和脉冲噪声环境.     

A Universal Wall-Current Detector

A universal X-band waveguide detector has been developed which offers the possibilities of a broad-band untuned detector with a stable frequency characteristic. The wall-current detector is a reflectionless two-port with an insertion loss, less than 0.05 db, no extra phase-shift, a sensitivity of about 10 mv/mw and a frequency characteristic which repeats within /spl plusmn/0.1 db over the 8.2-12.4 Gc band for any 1N26. This performance made it possible to flatten the output of a Hewlett-Packard sweep oscillator (as seen by another wall-current detector) within /spl plusmn/0.15 db over the whole X band. As a result many frequency-dependent measurements can now be done automatically with reasonable precision. Plotters and reflectometers will be simplified, resulting in a higher precision. Circular and ridge waveguide types have also been made. The latter seems very promising for an ultra broad-band detector. A sum detector and a difference detector have been made. They can be used for phase-sensitive detection, zero measurements, etc. The wall-current detector can easily be scaled down to mm waves.     

基于神经网络噪声检测的自适应中值滤波器

针对椒盐噪声污染图像的滤波问题,提出了一种基于前馈神经网络的噪声检测器。基于这种噪声检测方法,采用自适应中值滤波算法,依据像素点的不同属性采用不同的滤波策略。实验结果表明,该算法在有效去除椒盐噪声的同时更好地保留了图像的边缘和细节,是一种有效的图像去噪方法。     

基于PDTDFB变换域各向异性双变量模型和非局部均值滤波的图像去噪方法

为了有效去除图像噪声并保留更多图像细节信息,提出一种结合PDTDFB变换域各项异性双变量拉普拉斯模型和非局部均值滤波的自适应图像去噪算法.首先分析了PDTDFB变换系数的分布特点,使用各项异性双变量拉普拉斯模型作为其父子系数相关性的先验分布,在贝叶斯去噪框架下推导出闭式形式的各项异性双变量阈值函数,然后对估计的变换系数进行逆PDTDFB变换得到初步去噪图像,最后使用非局部均值滤波对其进行平滑处理.实验结果显示:本文所提算法去噪效果明显,与一些经典算法相比,本文方法在主客观上皆取得了有竞争力的结果.     

新颖的电压模式通用双二阶滤波器

提出了采用第二代电流传送器构成的电压模式三输入、单输出多功能通用双二阶滤波电路,该电路通过选择不同的输入信号,可在输出端得到电压模式二阶低通、高通、带通、陷波和全通五种滤波功能。每种滤波功能的滤波器的固有角频率ωｐ和品质因素Ｑｐ可实现正交调节,所有滤波器都具有低的无源和有源灵敏度。     

A Multipurpose Electronic Filter and Integrating Level Detector

A multipurpose electronic filter and integrating level detector suitable for electroencephalographic (EEG) and electromyographic recording and analysis is described. It uses solid-state components and is easily constructed. An application of the device in the detection of slow wave sleep (SWS) potentials is given.     

一种非开关型快速随机脉冲噪声降噪算法

为提高现有开关型随机脉冲噪声（Random-Valued Impulse Noise,RVIN）降噪算法的降噪性能,提出了一种基于卷积神经网络的非开关型RVIN快速降噪算法（Fast Non-switching RVIN Denoising Algorithm,FNRDA）.首先,利用噪声检测器随机地检测给定噪声图像中少量不同位置处的像素点;然后,将检测为RVIN噪声点的个数除以被检像素点总数转化为噪声比例值;最后,根据噪声比例值调用相应预先训练好的非开关型卷积神经网络降噪模型,快速且高质量地完成图像降噪任务.实验结果表明：所提出的非开关型FNRDA算法在各噪声比例下的综合性能（降噪效果和执行效率）优于经典的开关型RVIN降噪算法,适用于图像恢复、信号检测、无线通讯等实时系统中.     

A Theory of Impulse Noise in Telephone Networks

This paper presents a physical theory of impulse noise in telephone networks based on the assumption that impulsive disturbances can reverberate through a network for very long periods of time. A mechanism of regeneration and propagation of disturbances through signaling circuits is proposed, and the resulting reverberation is modeled as a random walk in one dimension. Theoretical results agree surprisingly well with empirical probability distributions of inter-error intervals in data transmission. However, direct experimental evidence is lacking to substantiate (or disprove) the physical mechanism on which the theory is based.     

基于横向型滤波器的多用户检测器

本文将横向型滤波器算法应用于CDMA系统之中，从而实现多用户检测的功能。分析和仿真结果表明，该类多用户检测器具有较好的抗“远近效应”能力和较为简单的结构，具有广泛的应用前景。     

一种基于噪声估计的彩色噪声滤除算法

在视频处理中，为了提高电视画面的清晰度，不但需要对亮度噪声进行滤除，对色度噪声的滤除也是必不可少的。文章的滤波算法是：先基于块操作对图像的噪声情况做一个大概的估计，然后根据估计的噪声情况对图像进行降噪或者不作处理。降噪的时候。对彩色脉冲和高斯噪声分别选择不同的阵噪算法。文章着重介绍了彩色脉冲噪声的滹除，该算法综合了线性和非线性矢量滤波，降噪效果明显,对高斯噪声采用矢量均值滤波。     

A CMOS Digitally Programmable Universal Current-Mode Filter

A new digitally programmable universal current-mode biquad filter is proposed. The filter is based on digitally controlled current followers (DCCFs). It utilizes gains of the DCCFs to provide precise frequency and/or gain characteristics that can be digitally tuned over a wide range. All parameters of the proposed filter can be adjusted independently. Experimental results obtained from a 0.35-$mu$m standard CMOS chip are provided.      

A Noise Suppressor for Neurophysiological Recording of Impulse Activity

A device is presented which utilizes a novel transistor switch for dc restoration of base line in neurophysiological recordings of impulse activity. A gate which operates the switch is derived from the initial rise of an impulse. The switch and associated circuitry allow only the impulses to pass and deliver no signal between impulses.     

A Novel Photonic Microwave Filter With Infinite Impulse Response

A novel design of a photonic microwave filter with infinite impulse response is presented and demonstrated experimentally, ft overcomes the problems due to optical coherence. The design exhibits substantial flexibility, permitting easy and continuous tunability of the free spectral range. In particular, when a Mach-Zehnder modulator is used in the filter, the passband of the filter response can be changed to stopband and vice versa. The design also provides scope for cascading more stages. Theoretical analysis and measured results are presented, showing a very good match between them.     

有色噪声下的不敏卡尔曼滤波器

有色噪声干扰情况下非线性系统的状态估计是许多实际工程需要解决的问题。通常的方法是利用扩展卡尔曼滤波方法将非线性系统线性化后,再利用线性系统的方法对有色噪声系统进行估计。然而,模型的线性化误差往往会严重影响最终的滤波精度,甚至导致滤波发散。为了避免此类误差,先通过对测量方程进行变换的方法,将观测方程的有色噪声转换为白噪声后,再利用不敏卡尔曼滤波方法,对系统的状态进行估计。虽然,该方法也需要对观测方程进行线性化,但是由于此线性化过程是在求解新量测方程的测量误差中进行,因此对系统的误差影响不是很大。仿真结果表明新方法能够有效地对有色噪声环境下系统的状态进行估计,性能要优于现有的一些基于EKF的方法。     

加性复合有色噪声下卡尔曼滤波模型

探讨定常线性系统被多种有色噪声污染下的Kalman滤波模型。首先,借助于经典的AR模型及QR分解,寻求系统噪声与量测有色噪声无关的增广系统;其次,利用外推法扩展此增广系统为系统噪声与量测噪声均为白噪声且相关的线性随机系统;进而,获得加性复合有色噪声下的Kalman滤波模型。数值实验说明所获模型比已报道的Kalman滤波模型更能有效地估计系统的状态。     

用管脚可编程滤波器件MAX264设计通用有源滤波器

本文介绍了美国MAXIM公司生产的管脚可编程通用开关电容滤波器件MAX264的内部结构及原理功能，在此基础上给出了一个基于软件无线电思想的可编程控制的滤波电路。