分数阶数字FIR微分器的快速WSLD设计算法

一阶逼近格林瓦尔-莱特尼科夫(G-L)加权系数的计算具有准确快速的递推公式,而高阶逼近鲁比希加权系数的求解则复杂度高,计算消耗时间长。本文通过傅里叶变换证明了鲁比希算子的逼近阶,并基于移位鲁比希算子提出一类四阶逼近的加权移位鲁比希差分(WSLD)算子。从数字信号处理角度分析WSLD算子滤波特性,设计基于WSLD算子的分数阶数字FIR微分滤波器并进行数值仿真验证。对比Al-Alaoui、鲁比希2种典型分数阶算子,结果表明,利用WSLD算子求解分数阶数字FIR滤波器滤波系数的算法简单、高效,且相对其他算子能有效减小吉布斯效应影响。     

全相位FIR滤波器族

本文构建了一套完整的包含四种类型FIR滤波器的设计体系—全相位FIR滤波器族.在该体系中,对由原频率采样法的系数向量h进行定义域延拓即形成多个子滤波器,将各子滤波系数对齐标号n排列起来即可形成循环移位阵,再将循环移位阵中各子滤波系数求和平均后即可得最终的FIR系数。理论和仿真实验均证明了全相位FIR滤波器族良好的频率特性,并且4种类型的全相位FIR系数的生成都具有简化设计步骤,无需迭代过程,从而本文提出的设计体系具有较大的应用前景.     

采用自适应滤波的干扰抑制

本文叙述了自适应滤波线路增强器的基本原理及其在从宽带信号中滤除窄带干扰方面的应用。自适应数字滤波器通过使一组滤波加权动态地适应信号的特征来处理被采样的数字信号。自适应滤波线路增强器根据这些加权的相关时间的不同,使这些加权自适应于从宽带信号中分离出窄带干扰。以非递归或递归两种形式构成的滤波器分别称作有限脉冲响应(FIR)滤波器和无限脉冲响应(IIR)滤波器。为了计算最佳的一组加权,已经研究出一种新算法,称为可变阶跃(VS)算法。本文示出了VS算法的计算机模拟结果并将它与使用样机所测得的结果加以比较。这些测试结果表明:对于脉动正弦波或其他频率捷变干扰那样的非平稳窄带干扰,这种自适应滤波器具有极好的跟踪特性。     

一种具有细节保护功能的改进型中值滤波器

针对椒盐噪声污染的图像提出了一种改进型中值滤波算法.该算法是一种自适应型中心加权的高效中值滤波算法.通过计算边缘隶属度来自适应地调整中心像素的权值,从而控制新的滤波器对图像不同区域进行不同程度的平滑,即对细节丰富的图像区域进行轻度的平滑,而对细节较少的图像区域进行重度的平滑.实验结果表明,新的滤波算法优于传统的中值滤波器及常规的中心加权中值滤波器.     

基于最小二乘法的对称分数延迟滤波器设计

针对现有分数延迟滤波器在应用过程中对于硬件资源消耗巨大的问题,提出一种优化设计可变分数延时(VFD)有限脉冲响应(FIR)数字滤波器的方法,优化后的滤波器在实现滤波器系数对称性的同时,其滤波性能也不弱于使用非对称系数的传统最小二乘法(WLS)加权滤波器。对称系数可变分数延时滤波器在滤波时仅需要总阶数的一半抽头系数进行计算,大大减少了运算资源,有效降低了实现成本。     

春秋视讯专栏

FIR滤波器—先进的FPGA技术对模拟电压信号进行滤波是一种消除非期望信号(如噪声)的方法,并且这种滤波突出感兴趣的滤波。传统的模拟滤波器通常仅用于比较简单的方法中,如高通、低通和带通滤波器。而今,Gage公司的14位数字信号采集卡可以实现复杂的滤波。这种新的FIR滤波器技术允许用户实时处理复杂的数字信号滤波。特性如下:●使FIR滤波器的阶数可以达到20阶,通过软件可以扩展带同步的39阶。●通过调节FIR滤波器的系数可以使其可以和特定波形的信号脉冲适配。●FIR滤波器可以通过Gage公司提供的硬件执行,允许主机并行运行其他程序…     

基于Matlab加噪语音的FIR滤波器设计

传统的FIR滤波器设计是根据给定的频率指标,设计出满足指标的系统函数.本文提出一种基于Matl8b加噪语音的FIR滤波器设计方法.该方法首先通过Matlab产生单频噪声,加入到语音信号中,并改变单频噪声的频率来调整FIR滤波器设计的难度;然后,根据混入噪声信号的频谱,设计出所需要的滤波频率指标;选择合适的窗函数,设计满...     

一种数字全通滤波器的设计方法研究

研究了一种数字全通滤波器的设计方法.对于一个平稳的全通滤波器,其分母多项式一定具有最小相位.该方法是基于最小相位滤波器的复倒谱系数和其群迟延函数以及其系统函数之间的关系,通过一个非线性的递归方程求解分母多项式的系数.由全通滤波器的特性已知,分母系数可以完全决定全通滤波器的传递函数.仿真结果表明这种方法能够使所设计滤波器的群延迟特性在整个频率范围内以近似理想的群延迟特性存在.并结合实现提出了一种用FIR逼近IIR的方法.     

基于自适应神经网络的二维线性相位FIR滤波器优化设计

提出一种基于自适应三角函数基神经网络的二维线性相位FIR滤波器优化设计方法.该方法根据二维线性相位FIR滤波器幅频响应特性,采用三角函数基神经网络优化算法计算滤波器系数,同时在神经网络训练过程引入自适应学习率算法,提高神经网络的学习效率和收敛速度.通过训练神经网络的权值,使二维线性相位FIR滤波器幅频响应与理想幅频响应...     

圆锥扫描体制雷达跟踪旋转目标的方法研究

针对圆锥扫描体制雷达对目标精密跟踪及测角时由于导弹目标自旋而引起的跟踪失控问题,提出了一种采用窄带FIR滤波器滤除自旋调制信号,提取锥扫信号的解决方法。FIR滤波器具有线性相位,但需要采用高阶滤波才能达到很好的带通特性。该方法经过计算机仿真产生高阶FIR滤波器系数,经过了仿真验证,并在导弹目标跟踪应用中取得了很好的效果。     

从混合有色噪声背景中提取正弦随相调频信号的方法

提出了从混合有色背景噪声中提取正弦随机调频信号方法－－基于高阶累积量FIR自适应滤波方法。其主要特点是：FIR自适应滤波系数是用输入信号的四阶以上累积量进行更新的；FIR自适应滤波器是收敛于与有用信号类型匹配的滤波器。因此，它既能有效地提取有用信号（匹配信号），又能有效地抑制混合有色噪声（非匹配信号）。仿真结果表明，与短时相关方法相比，该方法是很有效的。     

一种适用于DCO-OFDM系统的DFT信道估计算法

针对直流偏置光正交频分复用系统中传统离散傅里叶变换(DFT)信道估计算法运算复杂度高和循环前缀(CP)内存在非有效信道系数的问题,提出厄米特对称的DFT(H-DFT)阈值改进信道估计算法.首先,根据信道时域响应变换到频域满足厄米特对称的性质,只需对有效子载波的信道频域响应做厄米特对称即可获得全部子载波的信道频域响应;其...     

基于加权总体最小二乘正则化方法的混合滤波器组最优化设计

模拟分析滤波器组的实现欠理想、系统噪声以及数字综合滤波器有效阶数实现所带来的系统误差均有可能造成混合滤波器组的设计出现解不稳定、无唯一解等病态问题,影响混合滤波器组的准确重构效果。本文首先给出了满足准确重构条件下,以综合滤波器组频域响应为求解变量的混合滤波器组线性求解模型。针对线性方程中系数矩阵以及目标向量受扰动误差影响特点,提出一种新的基于加权总体最小二乘正则化算法的IIR形式综合滤波器设计方法。算法以系统扰动误差最小化为目标函数,根据随机误差变量的二阶统计特性,采用加权总体最小二乘算法抑制滤波器实现误差以及随机噪声等扰动因素影响,使得到的综合滤波器组频域响应解的加权误差平方和最小化,并通过Tikhonov正则化方法优化病态情况下方程组解的稳定性。提出一种IIR类型的综合滤波器系数的求解算法,并利用正则化方法优化滤波器系数,提高系统稳定性。该方法可应用于过采样混合滤波器组的设计。仿真结果表明该算法的有效提高系统鲁棒性和改善重构性能。      

Design of a C-Message Weight Digital Filter

This note describes an 8.0 kHz sampling rate discrete implementation of the C-message weight filtering characteristic. Included for this filter are the filter coefficients for an eight-bit realization and a tabulation and graph of the frequency response.     

Efficient weighted least-squares algorithm for the design of FIRfilters

The weighted least-squares (WLS) technique has been widely used for the design of digital FIR filters. In the conventional WLS, the filter coefficients are obtained by performing a matrix inverse operation, which needs computation of O(N³). The authors present a new WLS algorithm that introduces an extra frequency response including implicitly the weight function. In the new algorithm, the filter coefficients can be solved just by a matrix vector multiplication. It reduces the computational complexity from O(N³ ) to O(N²)     

基于sigmoid函数的Volterra自适应有源噪声对消器

该文介绍了一种新颖的非线性自适应有源噪声对消器基于sigmoid函数的Volterra自适应有源噪声对消器,并采用输入信号和瞬时误差归一化的LMS自适应算法调整其系数。这种基于sigmoid函数的Volterra自适应有源噪声对消器具有参数少和便于实现的模快化结构等优点。仿真结果表明:这种基于sigmoid函数的Volterra自适应有源噪声对消系统具有良好的抗噪声性能。     

Digital Laguerre filter design with maximum passband-to-stopband energy ratio subject to peak and Group delay constraints

In this paper, we formulate a general design of transversal filter structures with maximum relative passband-to-stopband energy ratio subject to complex frequency response constraints in the passband and the stopband as well as additional constraints such as constraints. These constraints are important for applications where the suppression of noise at certain frequencies are important. Additional constraints are introduced allowing approximately linear phase and constant group delay in the passband. For a given set of basis functions, the design problem can be formulated as a semi-infinite quadratic optimization problem in the filter coefficients, which are the decision variables to be optimized. In this paper, we focus on the design of digital Laguerre filter and digital finite impulse response (FIR) filter structures. A modified bridging algorithm is developed for searching for the optimum pole of the Laguerre filters. Design examples are given to demonstrate the effectiveness of the proposed algorithm.     

Instantaneous microwave frequency measurement based on hybrid microwave photonic filter

A novel photonic technique for instantaneous microwave frequency measurement based on hybrid microwave photonic filter （HMPF） is proposed and experimentally demonstrated. The HMPF is composed of an all-pass filter and a band-pass filter with negative coefficients. By properly controlling the power relationship between the all-pass filter and the band-pass filter, the HMPF can realize a monotonic frequency response, and then a unique relationship be- tween the output power and the input frequency is established. A high measurement resolution can be achieved for a given frequency range.     

IIR数字粉红噪声滤波器的优化设计

提出了用遗传算法优化IIR数字滤波器的传递函数，使其幅频响应曲线的斜率逼近一3dB／oct。用优化得到的数字滤波器对白噪声序列滤波即可获得粉红噪声。试验结果表明，用遗传算法优化得到的IIR滤波器的频响与理想的-3dB/oct曲线吻合得很好。     

Rapid identification of a sparse impulse response using an adaptive algorithm in the Haar domain

This paper proposes a fast convergence adaptive algorithm for identifying a sparse impulse response that is rich in spectral content. A sparse impulse response is referred here as a discrete time impulse response that has a large number of zero or near zero coefficients. The basic idea for rapid identification is to automatically determine the locations of the nonzero impulse response coefficients for their adaptation and eliminate the unnecessary adaptation of zero coefficients. The proposed method, which is called the Haar-Basis algorithm, employs a transform approach by modeling the sparse impulse response in the Haar domain. The Haar transform has many basis sets and each of them contains basis vectors that span the entire time domain range. This special nature of the Haar transform allows for the selection of one small subset of adaptive filter coefficients whose basis vectors span the entire range of the impulse response. These coefficients are adapted at the beginning and are then used subsequently to identify, from the hierarchical structure of the Haar transform, the rest of the filter coefficients that must be adapted to correctly model the unknown sparse impulse response. The consequence is avoiding adaptation of many zero coefficients, leading to a dramatic improvement in either convergence speed or steady state excess mean-square error (EASE), while requiring no a priori knowledge such as the number of nonzero coefficients in the unknown sparse impulse response. The proposed algorithm has been tested with a variety of unknown sparse systems using both white noise input and colored input whose spectrum closely resembles that of speech. Simulation results show that the new approach provides promising results.