二维数字滤波器的计算机辅助分析算法

本文提出了二维数字滤波器的计算机辅助分析算法，可导出任意拓扑结构的二维数字滤波器的传递函数、分析其频率响应对系统参数的灵敏度及系统的稳定性。由该算法可生成通用二维数字滤波器的计算机辅助分析软件，解决了高阶与结构复杂的二维数字滤波器的理论分析与设计上的困难。     

子波变换去噪的一种新算法

在图象平滑中，经常采用均值滤波和中值滤波。然而均值滤波对高斯白噪声比较有效而中值滤波对脉冲噪声比较有效。因而寻求对两种噪声都有效的去噪算法是我们所希望的。本文在概要介绍子波变换的基础上，首先从理论分析和实验计算两个方面详细讨论了脉冲信号和高斯白噪声的子波变换特性。然后说明了一种对脉冲噪声和高斯白噪声同时有效的新的去噪算法。最后利用改进的去噪算法对一维信号和二维信号进行了实验，并给出了数字仿真的结果。     

基于改进Hopfield神经网络的自适应二维噪声对消器

提出了基于连续型Hopfield神经网络(CHNN)的自适应二维噪声对消器,讨论了神经网络的结构和原理及相应的自适应滤波算法,并从理论上进行了论证.仿真结果表明相对于采用最小均方算法的二维线性噪声对消器,CHNN噪声对消器能更有效实现二维噪声的消除,保持原信号的完整性,获得较好的去噪声效果.     

相位噪声补偿新技术

文章介绍了两种补偿相位噪声的新技术,分别是补偿激光器相位噪声的数字前馈载波恢复算法和补偿非线性相位噪声的数字反向传播算法.其中数字前馈载波恢复算法能有效地提高能够容忍的激光器线宽;数字反向传播算法减少了非线性噪声,并能够大幅提高发射功率,以提高信噪比.     

乘性和加性噪声相关背景下的二维谐波频率估计

本文利用二维循环统计量方法对乘性噪声之间相关、乘性噪声和加性噪声之间也相关这种复杂噪声背景下的谐波恢复问题进行了研究.首先,提出了二维噪声互可混的概念,用它来体现多个二维噪声之间的关系;然后,在乘性噪声为非零均值时,定义了二维循环均值来估计信号频率.在乘性噪声和加性噪声为零均值时,定义特殊的二维六阶时间平均多矩谱切片来估计信号频率.仿真实验证明了算法的有效性.     

用WFT算法实现TDM/FDM信号变换的误差分析

本文分析了TDM/FDM变换复接系统中数字信号处理器的系数误差和定点运算误差,以及两种误差对于系统特性和噪声特性的影响。所分析系统是用维纳格阑-付里叶变换算法(WFTA) 数字多相网络,但给出的方法对于一般DFT 多相网络方案也是适用的。文中还分别给出了一般WFTA定点运算误差和复数数字滤波器定点运算误差的分析方法。     

基于二维循环统计量的二维谐波信号参数估计

本文利用二维循环统计量方法对二维平稳乘性噪声与二维平稳加性噪声共存情况下的二维谐波信号参数估计问题进行了讨论.利用二维循环统计量能够有效地抑制二维平稳乘性噪声和二维平稳加性噪声的特点,有效地从噪声中提取出信号参数.仿真实验对算法作了说明.     

二维谐波恢复及其时域分析

本文从一种不同于二维谱分析的新观点出发,研究二维谐波恢复问题,证明了白噪声中的二维正弦波的线性模型是一个特殊的二维ARMA过程,并提出了一种时域分析法,借助它可以高分辨检测出白噪声中的二维正弦波。     

色噪声背景下的二维谐波频率估计

针对色噪声背景下的二维谐波频率估计问题,本文提出了拓广的二维ESPRIT算法.该算法对二维MA模型的噪声具有比较好的抑制能力.同时,对于二维频率配对问题,本文给出了一种更为简便的方法.仿真实验验证了算法的正确性.     

全息光存储系统中交错技术的研究

在全息光存储系统中,数据以二维'页'的形式进行存储时,会引入大量的突发错误和随机错误.为了将大片的突发错误离散开,使其变为单个的随机错误,就需要使用数据交错技术.文中提出了两种二维交错结构,并在全息存储系统中对两种交错结构进行了仿真研究.仿真结果表明,这两种结构能有效地克服全息存储系统中产生的大尺寸的突发错误.     

Separate/joint optimization of error feedback and coordinate transformation for roundoff noise minimization in two-dimensional state-space digital filters

This paper is concerned with the minimization of roundoff noise subject to l/sub 2/-norm dynamic-range scaling constraints in two-dimensional (2-D) state-space digital filters. Two methods are proposed, with the first one using error feedback alone and the second one using joint error feedback and coordinate transformation optimization. In the first method, several techniques for the determination of optimal full-scale, block-diagonal, diagonal, and scalar error-feedback matrices for a given 2-D state-space digital filter are proposed. In the second method, an iterative approach for minimizing the roundoff noise under l/sub 2/-norm dynamic-range scaling constraints is developed by jointly optimizing a scalar error-feedback matrix and a coordinate transformation matrix, which may be regarded as an alternative approach to the conventional method for synthesizing the optimal 2-D filter structure with minimum roundoff noise. An analytical method for the joint optimization of a general error-feedback matrix and a coordinate transformation matrix under the scaling constraints is also proposed. A numerical example is presented to illustrate the utility of the proposed techniques.     

An Efficient State-Space Realization With Minimum Roundoff Noise Gain

This paper deals with efficient digital filter structures with roundoff noise consideration. Motivated by the direct-form II transposed (DFIIt) structure in rho-operator (rhoDFIIt) an alternative structure is obtained [Li in 2005, where, instead of the first-order rho-operators in rhoDFIIt, a set of second-order polynomial operators is used. In this paper, with the rounding before multiplication implementation taken into account, the equivalent state-space realization of the proposed structure by Li is derived and its roundoff noise performance is analyzed by deriving the roundoff noise expressions without/with error feedback consideration. This state-space realization can be efficiently implemented and has more degrees of freedom than its counterpart rhoDFIIt, which can be utilized to minimize the roundoff noise gain. A genetic algorithm is proposed to efficiently solve the optimal structure problem. Extensive examples are given to illustrate the advantage of this state-space realization and support the theoretical analysis     

并行计算的全通数字滤波器结构

本文提出了两类并行计算的全通数字滤波器结构,并通过状态空间分析方法论述了并行处理的原理.通过舍入噪声分析,给出了噪声增益的表达式,对于一个N阶全通滤波器,其舍入噪声增益为4N.数值算例验证了所提结构的性能,同时,由于其具备并行处理的能力,更加适合高吞吐量的系统实现.     

On the generalized DFIIt structure and its state-space realization in digital filter implementation

It is well known that for a digital filter of order p, the number of nontrivial parameters in the classical optimal state-space realizations is proportional to p/sup 2/, while the traditional shift operator z-based direct-form II transposed (zDFIIt) structure, though having poor numerical properties, is one of the most efficient structures, just possessing 3p+1 nontrivial parameters. In this paper, based on the concept of polynomial operators, a new structure is proposed for digital filter implementation, which is a generalization of the traditional zDFIIt and the prevailing /spl delta/DFIIt structures. This structure, denoted as /spl rho/DFIIt, possesses 3p+1 nontrivial parameters plus p parameters at choice. Expressions for evaluating the sensitivity measure and the roundoff noise gain are derived for the /spl rho/DFIIt structure and its equivalent state-space realization that has the same structure complexity. It is shown that the state-space realization always yields a smaller roundoff noise gain than the /spl rho/DFIIt structure. One of the nice properties of these two structures is that for a given digital filter, they can be optimized with the p free parameters. The optimal structure problems can be solved with exhaustive researching under practical considerations. Numerical examples are presented to illustrate the design procedure.     

Roundoff Noise Minimization for 2-D State-Space Digital Filters Using Joint Optimization of Error Feedback and Realization

The joint optimization problem of error feedback and realization for two-dimensional (2-D) state-space digital filters to minimize the effects of roundoff noise at the filter output subject to$L_2$-norm dynamic-range scaling constraints is investigated. It is shown that the problem can be converted into an unconstrained optimization problem by using linear-algebraic techniques. The unconstrained optimization problem at hand is then solved iteratively by applying an efficient quasi-Newton algorithm with closed-form formulas for key gradient evaluation. Analytical details are given as to how the proposed technique can be applied to the cases where the error-feedback matrix is a general, block-diagonal, diagonal, or block-scalar matrix. A case study is presented to illustrate the utility of the proposed technique.     

New criteria for asymptotic stability of one- and multidimensionalstate-space digital filters in fixed-point arithmetic

This paper addresses the problem of global asymptotic stability of one-dimensional (1-D) and multidimensional (m-D) digital filters with any combination of overflow and quantization nonlinearities. The stability analysis is carried out using 1-D and m-D state-space representations. The approach introduced allows one to determine the stability behavior of single-input single-output systems with overflow and quantization nonlinearities. The new criteria, based on previous stability results of digital filters with quantization schemes, are applicable to all arithmetic schemes. For the first time, results concerning general state variable representations of 1-D and m-D digital filters with the naturally occurring combination of two's complement truncation quantization and overflow are reported. Furthermore, significantly improved stability regions are obtained for digital filters with roundoff nonlinearities     

An improved orthogonal digital filter structure

A novel structure is derived for digital filter implementation. This structure is actually an improved version of an existing one in terms of implementation efficiency and reducing finite word length (FWL) effects. Expression of roundoff noise gain is obtained for the proposed structure. Design examples are given to demonstrate the performance of this structure and to compare it with the existing one and the classical minimum roundoff state-space realizations. Numerical examples show that the proposed structure outperforms the others in terms of minimizing roundoff noise as well as implementation efficiency.     

Implementation of 2-D pseudo-rotated digital filters using a forward lattice structure

The 1-D FDLS shows the localized feedback property and is suitable for modular and concurrent implementation. It is known that the 1-D FDLS shows interesting properties with respect to finite word-length effects. In this paper, a new result is given for the estimation of the lower and upper bound of the variance of the roundoff noise. It is presented how the FDLS can be incorporated to implement 2-D pseudo-rotated digital filters. The 1-D roundoff noise analysis is extended to the 2-D case. It is indicated how 2-D filter banks can be derived from the FDLS.     

Design of 3-D Noncausal Filters with Small Roundoff Noise and No Overflow Oscillations

The contribution of this paper consists of two individual parts. First, an invertible mapping technique is presented for 3-D digital system design, and it is applied to approximate 3-D noncausal filters in the spatial domain. Secondly, an algorithm is proposed for obtaining a structure for 3-D IIR filters with small roundoff noise and no overflow oscillations. The design of noncausal filters can be carried out by three steps: 1), a given noncausal impulse response is transformed into the first octant using the proposed 3-D invertible mapping technique; 2), the transformed impulse response in the first octant is approximated by balanced model reduction of 3-D separable denominator systems;3), the resultant 3-D IIR filter is transformed back to the original coordinates.     

Floating point arithmetic and digital filters

The roundoff noise properties of floating point digital filters are examined. To make the analysis tractable, a high level model to deal with the errors in the inner product operation is developed. This model establishes a broad connection between coefficient sensitivity and roundoff noise. Along with the model, an efficient procedure to keep track of the addition scheme used in the inner product, and to compute the statistics of the errors is introduced. A systematic procedure based on the model is then developed to derive general expressions for the roundoff noise of FIR, direct form IIR, and state-space filters. The expressions in the context of state space filters are explored in some detail. Optimality issues are considered, and it is shown that when double precision accumulation is used, the optimal filters are similar in nature to those derived in the context of fixed point arithmetic with the essential difference that they also do depend on the spectrum of the input signal. Optimality with respect to addition schemes, and second-order filters are also examined in some detail