基于余弦滚降特性的IIR余弦调制滤波器组的设计

提出一种新的近似完全重构因果稳定的IIR余弦调制滤波器组的设计方法.基于所定义的一种IIR余弦滚降原型滤波器,滤波器组所要求的平坦条件完全被满足.在预先给定极点值的条件下,滤波器组的设计问题可以写成一个凸极大极小优化问题,从而采用二阶锥规划法求解.求出的滤波器组具有合理的完全重构误差,且原型滤波器的多相因子的分母相同,简化了完全重构条件.采用该滤波器组作为约束非线性优化法的有效初值,进一步优化得到完全重构IIR余弦滤波器组.     

Design of nonuniform cosine-modulated filter-banks with the perfect-reconstruction property and arbitrary filter lengths

In this paper, a method is proposed to construct recombination nonuniform cosine-modulated filter banks (CMFBs) with a perfect-reconstruction property and with arbitrary filter lengths. In this filter bank (FB) structure, certain channels of an original M-channel uniform FB are merged by a set of transmultiplexers (TMUXs), yielding nonuniform outputs, and the length restrictions on the original CMFB and the recombination TMUXs are avoided, allowing them to have arbitrary filter lengths. By imposing certain improved matching conditions on the prototype filters, nonuniform FBs with arbitrary filter lengths and with good properties can be obtained. As a result, the flexibility of selecting modulation types and filter lengths is greatly increased in the design of recombination nonuniform CMFBs. Another benefit due to the flexibility is that the system delay can be reduced.     

Design of nonuniform cosine-modulated filter-banks with the perfect-reconstruction property and arbitrary filter lengths

In this paper, a method is proposed to construct recombination nonuniform cosine-modulated filter banks (CMFBs) with a perfect-reconstruction property and with arbitrary filter lengths. In this filter bank (FB) structure, certain channels of an original M-channel uniform FB are merged by a set of transmultiplexers (TMUXs), yielding nonuniform outputs, and the length restrictions on the original CMFB and the recombination TMUXs are avoided, allowing them to have arbitrary filter lengths. By imposing certain improved matching conditions on the prototype filters, nonuniform FBs with arbitrary filter lengths and with good properties can be obtained. As a result, the flexibility of selecting modulation types and filter lengths is greatly increased in the design of recombination nonuniform CMFBs. Another benefit due to the flexibility is that the system delay can be reduced.     

一种完全重构FIR滤波器组的设计

基于一种通道数为偶数的双正交线性相位完全重构FIR滤波器组的时域设计算法,提出了通道数为奇数的滤波器组设计算法应用的详细过程,并充分利用仿酉滤波器组的性质给出了相应的线性相位完全重构FIR仿酉滤波器组的设计算法,最后讨论了此算法改进并用于两通道长度不尽相等的线性相位完全重构FIR双正交和仿酉滤波器组的设计.     

Fusion of multispectral and panchromatic images using multirate filter banks

In this paper, an image fusion method based on the filter banks is proposed for merging a high-resolution panchromatic image and a low-resolution multispectral image. Firstly, the filter banks are designed to merge different signals with minimum distortion by using cosine modulation. Then, the filter banks-based image fusion is adopted to obtain a high-resolution multispectral image that combines the spectral characteristic of low-resolution data with the spatial resolution of the panchromatic image. Finally, two different experiments and corresponding performance analysis are presented. Experimental results indicate that the proposed approach outperforms the HIS transform, discrete wavelet transform and discrete wavelet frame.     

低码率小波图像编码中的分析/合成技术

针对在低码率小波图像编码中,不合适的分析／合成子系统会造成显著重构失真的问题,研究了分析／合成子系统对图像编码的影响,给出了在不同ＦＩＲＱＭＦ（对称镜像滤波器）下分析／合成子系统中有限长度信号的优化延拓方法及对应的滤波器位移要求,优化了分析／合成子系统的性能     

付立叶级数的奇偶谐波

在付立叶级数中，除了正弦波、余弦波外，还有的函数的付立叶级数只有奇次波而没有偶次波，或只有偶次波而没有奇次波，本文给出什么样的函数只有奇次波而没有偶次波，什么样的函数只有偶次波而没有奇次波，以及偶次波和奇次波的系数计算公式。     

具有奇偶性的多尺度小波

利用多尺度分析理论构造出了具有奇偶性的多尺度小波.这些小波函数在构造上更加随意并且同时兼备许多优良性质,如固定的短支集、任意奇数阶或者偶数阶的消失矩、奇偶性、正则性和正交性.因此,它们具有更高的逼近阶,能很好地解决边界的问题.     

Analysis of realizable rational decimated nonuniform filter banks with direct structure

In the design of nonuniform filter banks （NUFBs） with direct structure, the location of each analysis filter, corresponding to the sampling factor satisfying maximal decimation condition, should be set properly to avoid large aliasing. In this paper, a necessary and sufficient condition for the setting of the location of each analysis filter is derived. The NUFBs, we focus on, have rational decimation factors. Based on the derived condition, the frequency support of each analysis filter for the realizable NUFBs can be determined directly in such a way that the analysis filters can extract the corresponding bands of the input signal. This provides a guideline for the design of NUFBs with direct structure in choosing proper locations of analysis filters.     

调制型数字滤波器组的设计及实现方法

探讨满足精确重建条件的调制型数字滤波器组,提出了这种调制型数字滤波器组的设计及实现方法,计算机仿真实验证明该方法是简单和有效的.     

掺杂一维光子晶体透射谱研究

用传输矩阵法计算模拟掺杂（含缺陷）一维光子晶体模型（ABCnAB）m的透射谱,当n=1,（ABCAB）。的透射谱出现了有规律的共振透射带,具有宽带滤波的特性,当m=10时,（ABCAB）10随缺陷层C的折射率以的变化,禁带中心频率处（1．0ω／ω0）出现了一个带宽由大变小变化的透射带,且每个透射带又分裂为恒定透射率的多个透射峰;当m=10,n为奇数时,模型（ABCnAB）10的透射谱出现奇数个透射带,n为偶数时,出现偶数个透射带,且每个透射带均分裂为9个透射峰。这些特性可用于设计可调性多通道滤波器等。     

M带小波变换中一类新的滤波器组

借助 M带小波变换理论和滤波器组理论 ,采用框架算子的多相分解方法 ,构造出一类新的 M带小波变换的等价滤波器组。采用该方法 ,我们只需知道原始数据和等价滤波器组 ,就可方便地求出任一级的小波系数 ,为实时处理提供了可能。     

任意m(m≥2)个连续正整数n次幂代数和的奇偶性判定法

本文通过具体实例阐述了任意m(m≥2)个连续正整数n次幂代数和的奇偶性的求法及,奇偶性的判定方法,该判定方法将成为数的奇偶性理论中奇数和偶数的性质的重要补充。     

The boundary processing of wavelet based image compression

When an image, which is decomposed by bi-orthogonal wavelet bases, is reconstructed, some information will be lost at the four edges of the image. At the same time,artificial discontinuities will be introduced. We use a method called symmetric extension to solve the problem. We only consider the case of the two-band filter banks, and the results can be applied to M-band filter banks. There are only two types of symmetric extension in analysis phrase, namely the whole-sample symmetry (WS), the half-sample symmetry(HS), while there are four types of symmetric extension in synthesis phrase, namely the WS, HS, the whole-sample anti-symmetry (WA), and the half-sample anti-symmetry(HA) respectively. We can select the exact type according to the image length and the filter length, and we will show how to do these. The image can be perfectly reconstructed without any edge effects in this way. Finally, simulation results are reported.     

线性迭代算法设计双正交余弦调制滤波器组

介绍了一种用于设计双正交余弦调制滤波器组的线性化方法。该方法中，目标函数和完全重构条件均被表示成为原型滤波器系数矢量的二次函数形式。使用拉格朗日乘数方法，算法通过迭代求解线性方程来获得期望的原型滤波器系数矢量。该方法最大优点在于设计过程简单易行并且计算效率非常高。设计实例表明，该算法对于双正交余弦调制滤波器组的设计是非常有效的。     

基于余弦调制滤波器组的多载波调制

首先介绍了Ｍ带滤波器组的概念,然后给出基于此概念的ＣＭＦＢ余弦调制滤波器组的设计及实现,并根据计算机仿真结果,与ＤＭＴ在性能和复杂度上作了比较。     

基于二维DCT的OFDMA系统信道估计方法

在OFDMA(orthogonal frequency division multiple access)系统中,每个用户通过占用若干时频资源块以实现多址传输,此时传统的基于DFT(discrete Fourier transform)的高效信道估计算法将会产生难以消除的平底效应;另一方面,当终端高速移动时,基于DFT的时域插值亦将面临较为严重的性能损失.为了解决上述问题,提出一种基于二维DCT(discrete cosine transform)的信道估计算法.仿真结果表明,所提出的信道估计算法能以较低的实现复杂度获取逼近最优信道估计器的性能,且在低信噪比条件下亦可获取高精度的信道估计,有助于实现"绿色通信".     

巴特沃斯小波构造与应用研究

讨论了小波与正交滤波器组的相互构造关系，以及由正交滤波器组构造小波所要满足的正规性条件，分析比较了由有限冲激响应（FIR）滤波器组构造出的小波与无限冲激响应（IIR）滤波器组构造出的小波，将基于IIR滤波器组的7阶巴特沃斯小波与基于FIR滤波器的Daubechies小波在信号降噪中中的效果进行了比较，得到了低阶IIR滤波器组构造的小波可以与高阶FIR滤波器组构造出的小波分析效果相似，证明Daubechies小波作为小波变换的一个分支，可以在数字信号处理中得到良好的应用。     

单模压缩奇偶相干态的四次方压缩特性

用单模压缩算子作用在单模奇偶相干态上即可得到单模压缩奇偶相干态.本文研究了这类量子态的四次方压缩特性,结果表明单模压缩奇偶相干态存在很强的四次方压缩特性,并且压缩程度随着压缩参量r的增大而增强.     

多进制Haar与斜Haar小波在纹理分类中的应用

基于Walsh变换和斜变换给出了一种构造多进制Haar小波和多进制斜Haar小波的方法,并利用这些变换特有的快速算法加快了小波分解速度．实验中用该类小波分解图像,然后提取纹理图像的特征量,使用最小距离分类器进行纹理分类并比较了构造出来的各类小波的分类正确率,给出了选择小波基的原则．实验结果表明多进制斜Haar小波滤波器组具有更佳的分类效果．