On 2-D partial fraction decomposition

In this paper we introduce a mapping technique of two-dimensional (2-D) auto correlation sequences to one dimensional (1-D) auto correlation sequences and obtain certain results useful in the test for existence of the decomposition of the form

$\text{A(Z}{}_1\text{,Z}{}_2\text{)A(Z}{}_1{}^{\mathrm{?1}}\text{)}\text{B(Z}{}_1\text{,Z}{}_2\text{)B(Z}{}_1{}^{\mathrm{?1}}\text{)}\text{=}\text{P(Z}{}_1\text{,Z}{}_2\text{)}\text{B(Z}{}_1\text{,Z}{}_2\text{)}\text{+}\text{P(Z}{}_1{}^{\mathrm{?1}}\text{)}\text{B(Z}{}_1{}^{\mathrm{?1}}\text{)}$

for a stable 2-D transfer function of a recursive digital filter defined by

$\text{H(Z}{}_1\text{,Z}{}_2\text{)=}\text{A(Z}{}_1\text{,Z}{}_2\text{)}\text{B(Z}{}_1\text{,Z}{}_2\text{)}$

These results are simple alternative to that reported in the literature [7] earlier.     

A novel nonnegative decomposition method and its application to 2-D digital filter design

In designing two-dimensional (2-D) digital filters in the frequency domain, an efficient technique is to first decompose the given 2-D frequency domain design specifications into one-dimensional (1-D) ones, and then approximate the resulting 1-D magnitude specifications using the well-developed 1-D filter design techniques. Finally, by interconnecting the designed 1-D filters one can obtain a 2-D digital filter. However, since the magnitude responses of digital filters must be nonnegative, it is required that the decomposition of 2-D magnitude specifications result in nonnegative 1-D magnitude specifications. We call such a decomposition the nonnegative decomposition. This paper proposes a nonnegative decomposition method for decomposing the given 2-D magnitude specifications into 1-D ones, and then transforms the problem of designing a 2-D digital filter into that of designing 1-D filters. Consequently, the original problem of designing a 2-D filter is significantly simplified.     

On the use of continued fraction filter structures for the design of 2-D digital filters

In this paper a method for the realization of 2-D recursive digital filters of second order by means of continued fraction filter structures is presented. The proposed method is based on the interconnection of basic filter structures of first order and gives also the set of all 2-D transfer functions that are realizable by these structures. The general rule for interconnecting these basic structures is described. It is proved that, on the set of second order fraction filter structures, some classes of structures and ordering relations can be defined, so that the set of all the classes form a partially ordered set (poset). Those structures which least constrain the coefficients of the transfer function are defined maximum elements of the poset. It is shown that among all possible continued fraction structures of second order only six are suitable for realization of two dimensional filters. Some results following from the use of spectral transformations are discussed.     

Implementation of 2-D denominator-separable digital filters using first-order all-pass sections

It is established that denominator-separable transfer functions which characterize an important subclass of 2-D filters can be expressed as a linear combination of first-order (1-D or 2-D separable) all-pass transfer functions with real or complex coefficients. This type of expansion is referred to as all-pass expansion of the corresponding transfer function. Based on this all-pass expansion, we derive some efficient structures for the realization of 2-D denominator-separable filters using all-pass sections.On leave from S.V. University College of Engineering. Tirupati-517502, India.     

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。     

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.     

A Very Efficient Approach for the Synthesis of 2-D Recursive Fan Filters

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Design of separable-denominator 2-D digital filters using the reduced-dimensional decomposition model

A separable-denominator 2-D digital filter (SD-2DDF) can be decomposed into the cascade form of a pair of 1-D digital filters (1DDFs) with different delay elements. Based on this reduced-dimensional decomposition, in this paper, we propose a new technique for designing SD-2DDFs in the spatial domain. The technique determines the coefficient matrices of 1DDFs by nonlinear optimization techniques first, and then a SD-2DDF can be easily synthesized. In addition, since the existent 1-D linear system realization techniques can be used to choose a good starting point for the optimization, extremely accurate design results can be easily achieved.     

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.     

克服噪声不确定度的拟合优度检验频谱感知算法

针对已有的基于拟合优度(GoF)检验的频谱感知算法易受到噪声不确定度影响的问题,利用矩估计法或特征分解估计法对噪声方差进行实时估计,将采样数据处理为标准正态分布的信号,最后通过GoF检验来感知主用户的存在性.在减小GoF算法复杂度的同时,克服了噪声不确定度对算法性能的影响,仿真结果也表明了所提算法的有效性.     

有源相控阵天线发射方向图测试简易方法

有源相控阵天线需要对接收和发射两种状态的天线方向图进行测试。现有天线测试远场只能进行接收态的方向图测试,介绍了在远场进行发射态方向图测试的一种简易方法。利用远场的测试转台和发射喇叭,使用频谱分析仪接收有源相控阵天线发射的数据,编制测试软件采集处理数据,即能实现有源相控阵天线发射方向图的测试。该测试方法简单易行。     

ARMA-cepstrum Recursion Algorithm for the Estimation of the MA Parameters of 2-D ARMA Models

This paper considers the problem of estimating the moving average (MA) parameters of a two-dimensional autoregressive moving average (2-D ARMA) model. To solve this problem, a new algorithm that is based on a recursion relating the ARMA parameters and cepstral coefficients of a 2-D ARMA process is proposed. On the basis of this recursion, a recursive equation is derived to estimate the MA parameters from the cepstral coefficients and the autoregressive (AR) parameters of a 2-D ARMA process. The cepstral coefficients are computed benefiting from the 2-D FFT technique. Estimation of the AR parameters is performed by the 2-D modified Yule–Walker (MYW) equation approach. The development presented here includes the formulation for real-valued homogeneous quarter-plane (QP) 2-D ARMA random fields, where data are propagated using only the past values. The proposed algorithm is computationally efficient especially for the higher-order 2-D ARMA models, and has the advantage that it does not require any matrix inversion for the calculation of the MA parameters. The performance of the new algorithm is illustrated by some numerical examples, and is compared with another existing 2-D MA parameter estimation procedure, according to three performance criteria. As a result of these comparisons, it is observed that the MA parameters and the 2-D ARMA power spectra estimated by using the proposed algorithm are converged to the original ones     

基于数据共轭重排的修正二维MUSIC算法分析

在阐述二维MUSIC算法基本原理的基础上,通过将接收数据共轭重排的再利用、构造相关矩阵,提出一种基于正交阵列的修正二维MUSIC算法。在快拍次数有限时,此算法可以明显改善信号的波达方向估计性能,特别是相干信号波达方向(DOA)的估计性能,计算机仿真结果证明了该改进算法的有效性和可行性。     

二维零相位FIR数字滤波器设计的闭式最小二乘解

本文二维零相位ＦＩＲ数字滤波器的解析最小二乘设计技术。通过建立频域误差差函数的矩阵形式，并运用与设计问题有关的矩阵的一些性质，得到了滤波器系数的闭式解，使得由给定的频响指标可直接计算滤波器系数，而不必对矩阵进行数值示逆，也不需要基于迭代运算的优化过程。文中给出了滤波器实例，其结果证实了该设计方法的简便性与有效性。     

TDIE计算二维导体目标瞬态远场的新方法

提出了时域积分方程法(TDIE)求解二维导体目标瞬态散射时远场计算的新方法,该方法基于自由空间的二维推迟势,无需传统的两次傅里叶变换,表达形式简洁,易于编程计算.数值算例中,分别计算了TM和TE高斯脉冲平面波照射情况下,二维金属角反射器(开放体)和二维金属圆柱(闭合体)的瞬态远场,计算结果与频域矩量法(MOM)结合傅立叶逆变换(IDET)计算的结果进行了比较,二者完全吻合,充分验证了本方法的正确性.     

四分量二维紧凑格式频域有限差分方法对粗糙导体表面导波结构的分析

文章利用四分量紧凑格式的二维频域有限差分方法（2-DFDFD）,结合等效表面阻抗边界条件（SIBC）,对粗糙导体表面导波结构的传输特性进行数值分析。根据等效表面阻抗边界条件,可以方便地计算边界上的切向场。只要求出本征方程,在给定频率上的传播常数就可以作为其特征值而被求得。     

A computational method for the LU decomposition of rectangularmatrices and its implications to the realization of 2-D digital filters

The realization of 2-D digital filters based on the lower-upper triangular decomposition of the coefficient matrix is investigated. A numerical method based on the QA decomposition, which has some important characteristics, is proposed for reaching the LU structure. The coefficients in the final LU structure have values favorable to fixed-point arithmetic implementation. Furthermore, the QR structure can be used for the realization and possesses good numerical characteristics in terms of the approximate decomposition scheme. The symmetry in the impulse response coefficient matrix of an octagonally symmetric 2-D FIR filter is utilized to reduce the computational effort spent in the decomposition and the total number of multipliers in the final realization structure     

A technique for the design of 2-D recursive digital filters with guaranteed stability

In the present technique, the denominator and numerator in the filter are designed separately and recursively. First, the denominator coefficients, derived from the stable matrix of the Roesser model (the Fornasini-Marchesini second model), are found by minimizing a performance index through the alternating variable method. The numerator coefficients are then determined analytically by solving linear simultaneous equations. The above process will be repeated until there is negligible change in the objective function. Finally, a numerical example is given to illustrate the utility of the proposed technique.     

线结构光参数的简易标定方法

为了实现高效率、低成本、高精度地标定线结构光 的参数,本文提出了一种基于单个平面同心面靶标标定线结构光参数的新方法。该方法基于 三点透视模型和交比不变原理计算光平面上标定点的三维坐标,利用最小二乘法拟合平面方 程。在摄像机视野范围内自由移动平面靶标,同时保持结构光投射到靶标上同心圆之外的区 域,采集至少两幅图像即可完成线结构光参数的标定。 实验结果表明: 光平 面标定的均方根 误差约为0.05mm,传感器测量精度的相对误差约为0.3%,系统整体 测量精度约为0.1mm, 说明本文标定方法具有较高的标定精度。并且该方法同时适用于其它类型结构光的标定,通 用性较强,具有获取标定点效率高、计算简单且操作灵活方便等优点,适合现场标定。     

氮分压对磁控溅射制备TaN薄膜性能的影响

采用直流反应磁控溅射法制备了TaN薄膜,研究了φ(N2)对薄膜的结构和性能影响。研究发现,在N2分压(体积分数)为9%时,多相共存的TaN薄膜表现出TaN(200)面择优取向,方阻和αt达到最佳,其值为52Ω/□和–306×10–6/℃。薄膜的方阻、电阻温度系数αt和晶粒尺寸都随着N2分压的增大而增大:当N2分压高于11%时,薄膜的方阻和αt增长较快。