Design of face-centred orthorhombic filter banks

In this paper, a method to design the two-channel FIR linear-phase (LP) face-centred orthorhombic (FCO) filter banks with equiripple magnitude responses and perfect-reconstruction (PR) is presented. The necessary conditions of lengths of LP FCO filter banks satisfying the PR constraint are derived. An interior-point algorithm is utilized to optimize the peak ripples of the analysis filters and a first-order approximation skill is introduced to satisfy the PR constraint. The simulation example is presented to illustrate the effectiveness of this proposed design technique.     

Joint use of time-domain and windowed method for design of modulated DFT filter banks

A novel and efficient technique to design modulated discrete Fourier transform （DFT） filter banks is introduced in this paper. The proposed method first relaxes the limits that the synthesis filters are the time-reversed version of the analysis filters and then adopts the time domain formula of the perfect reconstruction property as the solution to design the synthesis filters. The prototype filter in analysis filter banks is designed based on Fourier-Kaiser window approach. Simulation results show that the designed filter banks approximately satisfy the perfect reconstruction with controllable reconstruction errors.     

A Design of 2 L-Channel FIR Paraunitary Filter Banks with Complex Coefficients

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On characterization of linear phase nonuniform filter banks

In this paper, a condition termed as linear phase condition (LPC), which ensures that the filters of a nonuniform filter bank are linear phase, is presented. It is observed that the proposed LPC is also applicable to the uniform filter bank case. Further, the utility of this LPC to find (i) necessary restrictions on the filters lengths, (ii) the number of symmetric and antisymmetric filters in the filter bank and (iii) filter bank decimation factors is also investigated. The results obtained for the different cases are also presented in the form of tables. These tables will facilitate the design of nonuniform filter bank by ruling out the non-solvable cases and by reducing the search space, thus saving the designers’ precious time.     

Time-domain design of FIR multirate filter banks

A new time-domain methodology for designing FIR multirate filter banks is proposed. The conditions for perfect reconstruction systems can only be met by a limited number of systems, and consequently one of the major problems is to design analysis and synthesis filters which reduce the reconstruction error to a minimum. A recursive technique is proposed which uses the synthesis filters from one iteration to update the analysis filters for the next. The Letter shows that this is computationally simpler than previously proposed time-domain methods and produces filter banks in which the reconstruction error is reduced to practically acceptable levels.<>     

一种新的调制型混合滤波器组设计算法

针对经典的准确重构混合滤波器组设计问题,提出一种调制型混合滤波器组(MHFB)的设计算法,推导了分析滤波器组系数矩阵的行列式与原型滤波器系数的解析关系,给出了具有普适性的综合滤波器组解的一般形式,并讨论了因果、稳定系统的设计方法。针对多通道HFB设计复杂的问题,提出一种FIR形式综合滤波器组的优化设计算法,适用于多通道HFB的设计。仿真结果验证了算法的有效性。     

Time-domain modified DFT modulated filter banks for multi-carrier transceiver systems

A time domain designing method is proposed for discrete Fourier transform （DFT） modulated filter banks （DFT-FBs） for application in multi-carrier transceiver systems. Instead of using the time-reversed pair limitation between the transmitting /receiving filter pair, the receiving filters in the proposed filter banks are derived from transmitting filters in accordance with the Moore-Penrose generalized inverse matrix. It can be freely obtained to design the transmitting prototype filter, which mainly affects the level of spectral containment. Furthermore, the symbol error rate （SER） performance of the proposed filter bank based trans-multiplexer with one tap equalizer is investigated in ideal channel and multi-path channel environments respectively. Simulation shows that the proposed approach can achieve significant SER reductions when square root raised cosine （RRC） prototype filter is used for comparing with the orthogonal frequency division multiplexing （OFDM） and the general DFT-FBs based applications.     

过采样精确重构余弦调制滤波器组的设计

本文首先推导出过采样滤波器组精确重构的条件,由于此时所需的约束条件数比临界采样时少,因而可以设计出频域衰减特性更好的滤波器用,然后提出了精确重构约束条件下原型概通江波器的一种新的设计方法,采用矢的二次型约束优化算法,该算法优化方便,收剑速度快,与其它方法相比,滤波器的阻带衰减大。     

数字滤波器组在多载波调制中的应用

介绍了用数字滤波器组实现多载波调制的原理、性能以及可能的研究方向,重点比较了用数字滤波器组实现多载波调制与用DFT实现多载波调制的性能,并给出了仿真结果。     

Optimal design of high-performance separable wavelet filter banks for image coding

An optimization-based method is proposed for the design of high-performance separable wavelet filter banks for image coding. This method yields linear-phase perfect-reconstruction systems with high coding gain, good frequency selectivity, and certain prescribed vanishing-moment properties. Several filter banks designed with the proposed method are presented and shown to work extremely well for image coding, outperforming the well-known 9/7 filter bank from JPEG 2000 in most cases. With the proposed design method, the coding gain can be maximized with respect to the separable or isotropic image model, or jointly with respect to both models. The joint case, which is shown to be equivalent to the isotropic case, is experimentally demonstrated to lead to filter banks with better average coding performance than the separable case.During the development of the proposed design method, filter banks from a certain popular separable two-dimensional (2D) wavelet class (to which our optimal designs belong) were observed to always have a higher coding gain with respect to the separable image model than with respect to the isotropic one. This behavior is examined in detail, leading to the conclusion that, for filter banks belonging to the above class, it is highly improbable (if not impossible) for the isotropic coding gain to exceed the separable coding gain.     

线性相位余弦调制滤波器组研究

图像子带编码要求滤波器组具有线性相位特性，非线性相位特性可对图像编译码带来影响。现研究了一种具有线性相位的最大抽取FIR余弦调制滤波器组，该滤波器组中每一个滤波器都具有线性相位，且由原型滤波器经余弦序列调制得到。经推导这种滤波器组可以设计成具有近似准确重构（NPR）特性或准确重构（PR）特性，文中分别给出了两种情况下滤波器组应满足的条件。通过对一幅图像的二维可分离滤波实验说明了当原型滤波器满足一定条件时滤波器组是准确重构的。     

Optimal wavelet filter banks for regularized restoration of noisy images

Regularized image restoration methods efficiently handle the ill-posed problem of image restoration. Nevertheless, the issue of selecting the regularization parameter as well as the smoothing filter still constitutes an open research topic. A model of regularized image restoration is introduced and analyzed in this paper. The proposed model assumes that wavelet filter banks replace the smoothing filter of conventional regularized restoration. Filter factorizations for the optimal design of wavelet filter banks using the generalized-cross-validation (GCV) criterion are presented, and novel expressions of the influence matrix, which is used to calculate the GCV error, are derived. The error of the GCV method is expressed in terms of the modulation matrix of the filter bank and the modulation vector of the degradation filter. The expressions are given in general form for optimal wavelet filter bank design upon arbitrary sampling lattices. The numerical examples of image restoration using the proposed method that are presented indicate significant signal-to-noise ratio improvement, _SNR , compared to image restoration methods that employ the Laplacian as the smoothing filter.     

基于DSP+Builder线性相位滤波器组格型设计与实现

分析了线性相位完全重构滤波器组(LPPRF)的分析滤波器和综合滤波器,研究了一种线性相位滤波器组设计方法,格型结构。通过求解滤波器组的Lattice系数,进行了两通道线性相位完全重构滤波器组的格型结构设计。提出一种设计方案,利用DSP Builder技术,将Matlab/simulink设计工具和QuartusⅡ设计工具结合起来,实现有限冲激响应格型滤波器组.并以一个高阶低通FIR格型滤波器组的实现为例,设计并完成软硬件仿真与验证。结果表明,该方法简单易行,能满足设计要求。     

Reduction of transients during lifting based spatial switching of two-channel filter banks

Time/space varying filter banks (FBs) are useful for non-stationary images. Lifting factorization of FBs results in structural perfect reconstruction even during the transition from one FB to other. This allows spatial switching between arbitrary FBs, avoiding the need to design border FBs. However, we show that lifting based switching between arbitrarily designed FBs induces spurious transients in the subbands during the transition. In this paper, we study the transients in lifting based switching of two-channel FBs. We propose two solutions to overcome the transients. One solution consists of a boundary handling mechanism to switch between any arbitrarily designed FBs, while the other solution proposes to design the FBs with a set of conditions applied on lifting steps. Both solutions maintain good frequency response during the transition and eliminate the transients. Using the proposed methods, we develop a spatial adaptive transform by switching between the long length FBs (either the JPEG2000 9/7 FB or the newly designed 13/11 FB) and the short length FBs (JPEG2000 5/3 FB) for lossy image compression. This adaptive transform shows PSNR improvement for images over JPEG2000 9/7 FB in low bit rate region (up to 0.2 bpp) and subjective improvements with reduced ringing up to medium bit rates (up to 0.6 bpp).     

A new algorithm for linear-phase paraunitary filter banks with pairwise mirror-image frequency responses

Subband filter banks have attracted much attention during the past few years. In this paper, an efficient design algorithm, which leads to linear-phase paraunitary filter banks with pairwise mirror-image frequency responses, is revisited and further studied. New lattice structures are presented to extend the algorithm to the case where the number (M) of channels is odd. Design examples of filter banks with 3 and 5 channels are presented.     

A Fast FIR filtering technique for multirate filters

This paper presents a technique for applying Fast FIR Algorithms (FFAs) to interpolation and decimation filters. In the event that the prototype filter has a symmetric impulse response, it is shown that the subfilters which result from the application of the FFA will be jointly symmetric. This fact may be exploited in order to further reduce the computational complexity of the system. The effect of transposition upon the proposed structure is discussed, and it is shown that transposition yields a more economical structure in the case of a decimation filter. The computational complexity of the proposed schemes is shown to compare favorably with that of the standard parallel filtering approach.     

多采样率信号处理的发展

数字通信系统中,为适应传输、降低资源消耗、适于处理操作,常需要变换信号的采样率。多采样率信号处理理论从语音信号处理中发展起来,在应用中不断丰富。随着软件无线电的应用,多采样率变换在数字信号领域占据越来越重要的地位。多采样率信号处理技术与小波分析、分数阶傅里叶变换等其他信号处理技术相结合是未来发展的方向。     

Top-down design of a VLSI digital filter bank

This paper relates theoretical investigations in digital signal processing (DSP) to the design of a VLSI digital filter bank (DFB). Emphasis is on a top-down approach to identify multilevel parallelisms inherent in a generic DSP algorithm and a new VLSI architecture. System level control and communication requirements are examined. Finite word length effects on filter accuracy are identified. The complexity of filter modules is reduced by partitioning large filter functions into a sum of smaller subfunctions. A memory intensive architecture minimizes design time. Up to 100 DRF modules are configured in parallel to perform signal processing up to 20 MHz. This VLSI DFB out performs sequential von Neumann architectures by several orders of magnitude using the same level of VLSI technology.     

带通滤波器的结构和工艺设计

介绍了一种新型滤波器的结构、工艺设计,分析了该滤波器的结构特点和加工工艺。试验结果表明,该滤波器达到了设计要求。