可规划相位FIR滤波器的神经网络设计方法

本文针对可规划相频响应的实系数FIR滤波器的逼近问题,采用一个三层复激活函数前馈神经网络来实现。该网络隐层各神经元的激活函数为复指数函数,将滤波器系数作为隐层各神经元到输出层的连接权值,通过对误差函数的最小化来调整权值,并根据网络特性与所要设计的滤波器的特点,提出了一些实际设计中训练样本集选取与误差加权值设置的规则。依托所采用的神经网络,根据上述规则,进行了两例可规划相频特性的实系数FIR滤波器的设计,结果表明所设计滤波器的相频响应较好地满足了设计要求。     

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...     

An iterative algorithm for optimal design of non-frequency-selective FIR digital filters

This paper proposes a novel iterative algorithm for optimal design of non-frequency-selective Finite Impulse Response （FIR） digital filters based on the windowing method. Different from the traditional optimization concept of adjusting the window or the filter order in the windowing design of an FIR digital filter, the key idea of the algorithm is minimizing the approximation error by successively modifying the design result through an iterative procedure under the condition of a fixed window length. In the iterative procedure, the known deviation of the designed frequency response in each iteration from the ideal frequency response is used as a reference for the next iteration. Because the approximation error can be specified variably, the algorithm is applicable for the design of FIR digital filters with different technical requirements in the frequency domain. A design example is employed to illustrate the efficiency of the algorithm.     

具有任意频响的二维FIR数字滤波器设计的闭式最小二乘解

本文研究具有任意频响特性的二维ＦＩＲ数字滤波器的最小二乘设计问题。     

二维半平面线性相位FIR数字滤波器的最小二乘设计方法

本文研究了二维线性相位实系数FIR数字滤波器的最小二乘设计问题，导出了滤波器系数的闭式解。运用给出的计算公式可方便地计算滤波器的系数，而不必对矩阵进行数值求逆运算也不需要复杂的优化过程．设计实例表明本文给出的方法程序简单、计算时间极短．     

粒子群优化算法在FIR数字滤波器设计中的应用

本文针对有限脉冲响应(FIR)数字滤波器的设计实质上是一个多参数优化问题,提出了一种用粒子群优化算法(PSO)设计FIR数字滤波器的方法.首先将滤波器的设计问题转化为滤波器参数的优化问题,然后利用粒子群优化算法对整个参数空间进行高效并行搜索以获得参数的最优化.FIR数字低通、带通滤波器设计实例证明了该方法的有效性和优越性.     

Method for FIR filters design with compressed cosine using Chebyshev's norm

This paper considers a new method for FIR filters design. The method uses an L_∞ optimality norm. To achieve a better approximating effect, a new modulating function which compresses the oscillations of the cosine is proposed. A parameter sets the gradient of the modulating function, with respect to the oscillations’ compression. The approximating polynomial is carried out using Remez’ exchange algorithm. An optimal polynomial with lowest possible (four) degree, that approximates an ideal filter's response with high precision is proposed. With the proposed method a FIR filter with arbitrary specifications can be designed. Design examples of FIR filters with a minimization of calculation are performed. The obtained filter's responses are close to the ideal response. The design examples demonstrate that the proposed approach may be a good alternative in several applications.     

Design of linear or minimum-phase fir filters by constrained chebyshev approximation

Constrained Chebyshev approximation is a known mathematical problem, and Remes' type algorithms for finding the solution have been described. It is shown in this paper that the classical Parks-McClellan program can be converted into a general program for constrained approximation. The program can serve for the design of both linear and minimum phase FIR digital filters.     

Design of two-dimensional directional filters

A directional filter has a passband extending fully along a straight line passing through the origin. In its original form the transformation technique, a powerful tool for designing two-dimensional FIR filters, is not useful to design such a filter. In this communication we suggest a few analytical and optimisation-based methods to design directional filters using the transformation technique. The superiority of the proposed methods over existing techniques is demonstrated.     

基于MATLAB的FIR数字滤波器的设计

数字滤波技术是数字信号处理的一个重要组成部分.文中叙述了数字滤波的相关理论,介绍了应用MATLAB仿真工具设计有限冲击响应(FIR)数字滤波器的流程,并给出了滤波器频率响应曲线的仿真结果,结果表明满足技术指标的要求.     

Design of optimal minimum phase FIR filters by direct factorization

An improved method of designing optimal minimum phase FIR filters by directly finding zeros is proposed. The zeros off the unit circle are found by an efficient special purpose root-finding algorithm without deflation. The proposed algorithm utilizes the passband minimum ripple frequencies to establish the initial points, and employs a modified Newton's iteration to find the accurate initial points for a standard Newton's iteration. We show, with examples, that the proposed algorithm can be used to design very long filters (L = 325) with very high stopband attenuations.     

Cascade realization of linear phase fir filters with low sensitivity

The errors due to coefficient quantization in a digital filter are sensitive functions of its pole and zero locations. In this paper, a detailed analysis is made of the sensitivity, with respect to the location of zeros, of elemental fourth-order sections, for cascade realization of linear phase FIR filters. New structures are suggested for the realization of the sections with low sensitivity. Performance analysis of these structures in implementation of a few representative filters indicates their suitability for practical applications.     

On design of a novel class of selective CIC FIR filter functions with improved response

The Cascaded-Integrator-Comb (CIC) filter is a non-recursive (FIR) filter which is multiplier free, consisting only of two building blocks (simple integrator stage and simple comb filter stage) and has a linear phase. This paper summarizes some key points of classical CIC filters and proposes a novel class of CIC FIR filter functions. A novel class of CIC filter functions maintains simplicity of FIR filters by avoiding the multipliers, but shows excellent performances in term of insertion loss in stopband and selectivity with respect to conventional CIC filters. A set of simulations along with illustrative examples is conducted in order to compare the attenuation characteristics of the classical CIC filter functions and the proposed novel class of selective CIC FIR filter functions. For the same level of a constant group delay τ = 45.5 s, a classical CIC filter function has insertion loss of 166.3 dB, and designed novel filter function has a higher level of insertion loss 206.55 dB.     

基于人工蜂群算法的FIR滤波器设计

FIR滤波器设计是数字信号处理领域中的重要课题之一。最优化FIR滤波器设计可以抽象为一个最优化问题,采用启发式算法来求解。作为一种新型启发式算法,人工蜂群算法由于其原理简单、控制参数少、鲁棒性强等优点,已被越来越多的学者所关注。本文采用人工蜂群算法优化FIR滤波器设计,研究了两者的结合机理,讨论了具体实现步骤,并通过仿真验证了该方法的有效性。     

Design of linear phase FIR filters using fractional derivative constraints

In this paper, the designs of linear phase FIR filters using fractional derivative constraints are investigated. First, the definition of fractional derivative is reviewed briefly. Then, the linear phase FIR filters are designed by minimizing integral squares error under the constraint that the ideal response and actual response have several same fractional derivatives at the prescribed frequency point. Next, the fractional maximally flat FIR filters are designed by letting the number of fractional derivative constraints be equal to the number of filter coefficients. Finally, numerical examples are demonstrated to show that the proposed method has larger design flexibility than the conventional integer derivative constrained methods.     

Design of FIR digital filters with flatness constraints for the error function

A method will be presented for the approximation of a desired frequency response by the frequency response of a FIR filter. It is possible to match the functional values and an arbitrary number of derivatives of both responses for zero frequency, thus making the error flat up to a desired degree. Remaining degrees of freedom are used for a weightedL ₂-approximation. Closed form design formulae will be given.     

Design of 2-D FIR Filters by a Feedback Neural Network

A Hopfield-type neural network for the design of 2-D FIR filters is proposed. The network is contrived to have an energy function that coincides with the sum-squared error of the approximation problem at hand and by ensuring that the energy is a monotonic decreasing function of time, the approximation problem can be solved. Two solutions are obtained. In the first the 2-D FIR filter is designed on the basis of a specified amplitude response and in the second a filter that has specified maximum passband and stopband errors is designed. The network has been simulated with HSPICE and design examples are included to show that this is an efficient way of solving the approximation problem for 2-D FIR filters. The neural network has high potential for implementation in analog VLSI and can, as a consequence, be used in real-time applications.     

TITO系统中盲FIR信道辨识方法的性能分析

近年来，统计信号处理已经成为无线通信发展中的一项关键技术．特别是被ISI和MAI严重污染的宽带多用户通信系统。针对TITO（Two-Input-Two-Output）情况下，交叉信号混叠的信道的盲辨识问题介绍了一种分析解法，数学工具是SOS（Second-Order-Statistics）。在阐述问题的时候，认为源谱和混叠信道都是未知的，如果源相关信息有效．这种方法能解决通常的MIMO（Multiple-Input-Multiple-Output）系统问题。针对这种方法，我们对他作了性能分析，仿真结果表明他可以较好地辨识混叠滤波器，具有较强的鲁棒性。并用维纳滤波的方法恢复出了原始语音信号，证明这种方法也适用于非平稳信号的情况。     

基于DSP的FIR低通滤波器设计

介绍了FIR滤波器的基本结构和设计方法。根据要求,借助MATLAB辅助工具采用窗函数方法对滤波器的系统函数进行设计。利用设置循环缓冲区的方法对数据进行存储,通过DSP汇编语言编程,结合TMS320C5402为核心的实验平台实现了FIR低通滤波器的设计。实验结果表明,该设计精度高、稳定性好,操作方便,有一定的实用价值。     

Adaptive reduced-rank LCMV beamforming algorithms based on joint iterative optimization of filters: Design and analysis

This paper presents reduced-rank linearly constrained minimum variance (LCMV) beamforming algorithms based on joint iterative optimization of filters. The proposed reduced-rank scheme is based on a constrained joint iterative optimization of filters according to the minimum variance criterion. The proposed optimization procedure adjusts the parameters of a projection matrix and an adaptive reduced-rank filter that operates at the output of the bank of filters. We describe LCMV expressions for the design of the projection matrix and the reduced-rank filter. We then describe stochastic gradient and develop recursive least-squares adaptive algorithms for their efficient implementation along with automatic rank selection techniques. An analysis of the stability and the convergence properties of the proposed algorithms is presented and semi-analytical expressions are derived for predicting their mean squared error (MSE) performance. Simulations for a beamforming application show that the proposed scheme and algorithms outperform in convergence and tracking the existing full-rank and reduced-rank algorithms while requiring comparable complexity.