共查询到19条相似文献,搜索用时 875 毫秒
1.
小波滤波器的设计是小波分析的关键,本文给出了任意阶正则线性相位近正交小波滤波器的特征滤波器设计方法。 相似文献
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小波滤波器的设计是小波分析的关键。本文给出了任意2阶正则线性相位近正交小波滤波器的特征滤波器设计方法。 相似文献
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本文论述了由双正交完全重建滤波器组构造高度正则的双正交小波基的充分条件和构造方法,系统地研究了双正交线性相位FIR完全重建滤波器组的解的结构和已知H0(z)构造完全重建滤波器组的方法,并且实现了用单一的传递函数A(z)构造线性相位FIR双正交完全重建滤波器组的设计方法。这种方法的突出优点是滤波器组分析、合成部分中的滤波器可以用数值优化的方法使两者同时逼近理想低通滤波器和理想高通滤波器,即具有良好的频率选择性,并且所有滤波器都具有线性相位的特点。该滤波器组具有良好的梯形实现结构。在具体的滤波器设计中提出了基于均方误差最小准则的特征滤波器的设计方法和基于误差最大值最小准则的Remez交换法。而且上述方法设计的滤波器组可以构造出具有高度正则性的光滑的双正交小波基。 相似文献
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本文提出了小波变换中线性相位上有任意阶正则性的FIR共轭镜像滤波器的逼近方法,证明用此方法获得的滤波器均方误差最小,并比较了它的幅频特性、能量集中特性、正则性。实验表明,本文得到的滤波器具有很好的综合性能,适于进行数据压缩的应用。 相似文献
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本文提出了一种新型的全相位DFT数字滤波器频率响应的求取方法—循环移位图法,它是基于全相位滤波器和原有FIR滤波器的相互关系而构造的,充分体现了Fourier变换的循环移位性质和卷积窗的关系。该方法直观,深刻反映了全相位滤波器的内在机理。文中以N=3为例,说明了全相位滤波器的衍生过程。并以N=7阶全相位滤波器为例,分别在无窗、单窗和双窗条件下,推导出了全相位滤波器频率响应的数学表达式,并且用该表达式结合实验结果解释了全相位滤波器的优良特性。然后分别用所有数字角频率的正弦信号对全相位数字滤波器进行仿真实验测试,该仿真实验证明:测试出的频率响应曲线和理论推导完全一致。本文最后还推导出任意阶、任意种加窗方式下的全相位数字滤波器的频率响应公式。 相似文献
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给出了一种利用B样条构造具有线性相位的紧支集对偶尺度函数,对应的紧支集双正交小波及其相应的FIR滤波器组的方法。 相似文献
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航空图像压缩的双正交小波滤波器整数化设计 总被引:1,自引:1,他引:0
在航空图像压缩中,通常采用具有线性相位、正则性、消失矩和完全重构,及适于硬件实现、实时等特性的小波。根据小波滤波器设计,提出了一种基于图像压缩的构造整数双正交小波滤波器的设计方法。从选择小波基的原则为出发点,以CDF9-7小波基为参考,以压缩效果为准则来构造出更优的双正交整数小波基,并且采用航空图像为标准训练图像,以压缩比、峰值信噪比、压缩后保留能量百分比为参数,来寻找最优的小波基。试验结果证明,此方法可以实施非常简单的、无浮点乘法的运算,因而减少运算复杂性以及降低小波硬件实现的难度。 相似文献
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It is well known that FIR filter banks that satisfy the perfect-reconstruction (PR) property can be obtained by cosine modulation of a linear-phase prototype filter of length N=2mM, where M is the number of channels. In this paper, we present a PR cosine-modulated filter bank where the length of the prototype filter is arbitrary. The design is formulated as a quadratic-constrained least-squares optimization problem, where the optimized parameters are the prototype filter coefficients. Additional regularity conditions are imposed on the filter bank to obtain the cosine-modulated orthonormal bases of compactly supported wavelets. Design examples are given 相似文献
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We describe a new iterative method to design two-dimensional linear-phase FIR filters with arbitrary magnitude characteristic. The procedure is simple and can be used easily in designing filters of large order. This method is based on the use of the method of projection on to convex sets and can be implemented using the FFT algorithm. 相似文献
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A method is presented to synthesize wideband linear-phase finite-impulse-response (FIR) filters with a piecewise-polynomial-sinusoidal
impulse response. The method is based on merging the earlier synthesis scheme proposed by the authors to design piecewise-polynomial
filters with the method proposed by Chu and Burrus. The method uses an arbitrary number of separately generated center coefficients
instead of only one or none as used in the method by Chu–Burrus. The desired impulse response is created by using a parallel
connection of several filter branches and by adding an arbitrary number of center coefficients to form it. This method is
especially effective for designing Hilbert transformers by using Type 4 linear-phase FIR filters, where only real-valued multipliers
are needed in the implementation. The arithmetic complexity is proportional to the number of branches, the common polynomial
order for each branch, and the number of separate center coefficients. For other linear-phase FIR filter types the arithmetic
complexity depends additionally on the number of complex multipliers. Examples are given to illustrate the benefits of this
method compared to the frequency-response masking (FRM) technique with regard to reducing the number of coefficients as well
as arithmetic complexity. 相似文献
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It is shown that the singular-value decomposition (SVD) of the sampled amplitude response of a two-dimensional (2-D) digital filter possesses a special structure: every singular vector is either mirror-image symmetric or antisymmetric with respect to its midpoint. Consequently, the SVD can be applied along with 1-D finite impulse response (FIR) techniques for the design of linear-phase 2-D filters with arbitrary prescribed amplitude responses which are symmetrical with respect to the origin of the (ωΨω2) plane. The balanced approximation method is applied to linear-phase 2-D FIR filters of the type that may be obtained by using the SVD method. The method leads to economical and computationally efficient filters, usually infinite impulse response filters, which have prescribed amplitude responses and whose phase responses are approximately linear 相似文献
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Hakan Johansson 《Circuits, Systems, and Signal Processing》2006,25(2):175-200
This paper introduces two classes of frequency-response masking
(FRM) linear-phase finite (length) impulse response (FIR)
filters for interpolation and decimation by arbitrary integer
factors M. As they are based on the FRM approach, the proposed
filters are low-complexity (efficient) sharp-transition
linear-phase FIR interpolation and decimation filters. Compared
to previously existing FRM linear-phase FIR filter classes for
interpolation and decimation, the new ones offer lower
complexity and more freedom in selecting the locations of the
passband and stopband edges. Furthermore, the proposed classes
of FRM filters can, as special cases, realize efficient
Mth-band FRM linear-phase FIR interpolation and decimation
filters for all values of M. Previously, only half-band
(M = 2) FRM linear-phase FIR filters have appeared in the
literature. The paper includes design techniques suitable for
the new filters and design examples illustrating their
efficiency. 相似文献
16.
This paper discusses a method of regularity imposition onto biorthogonal linear-phase M-band filterbanks using the lattice structure. A lifting structure is proposed for lattice matrix parameterization where regularity constraints can be imposed. The paper focuses on cases with analysis and synthesis filterbanks having up to two degrees of regularity. Necessary and sufficient conditions for regular filterbanks in terms of the filter impulse response, frequency response, scaling function, and wavelets are revisited and are derived in terms of the lattice matrices. This also leads to a constraint on the minimum filter length. Presented design examples are optimized for the purpose of image coding, i.e., the main objectives are coding gain and frequency selectivity. Simulation results from an image coding application also show that these transforms yield improvement in the perceptual quality in the reconstruction images. The approach has also been extended to the case of integer/rational lifting coefficients, which are desirable in many practical applications. 相似文献
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The singular-value decomposition (SVD) technique is investigated for the realization of a general two-dimensional (2-D) linear-phase FIR filter with an arbitrary magnitude response. A parallel realization structure consisting of a number of one-dimensional (1-D) FIR subfilters is obtained by applying the SVD to the impulse response of a 2-D filter. It is shown that by using the symmetry property of the 2-D impulse response and by developing an appropriate unitary transformation, an SVD yielding linear-phase constituent 1-D filters can always be obtained so that the efficient structures of the 1-D linear-phase filters can be exploited for 2-D realization. It is shown that when the 2-D filter to be realized has some specified symmetry in its magnitude response, the proposed SVD realization would yield a magnitude characteristic with the same symmetry. An analysis is carried out to obtain tight upper bounds for the errors in the impulse response as well as in the frequency response of the realized filter. It is shown that the number of parallel sections can be reduced significantly without introducing large errors, even in the case of 2-D filters with nonsymmetric magnitude response 相似文献
18.
We have developed an algorithm based on synthetic division for deriving the transfer function that cancels the tail of a given arbitrary rational (IIR) transfer function after a desired number of time steps. Our method applies to transfer functions with repeated poles, whereas previous methods of tail-subtraction cannot. We use a parallel state-variable technique with periodic refreshing to induce finite memory in order to prevent accumulation of quantization error in cases where the given transfer function has unstable modes. We present two methods for designing linear-phase truncated IIR (TIIR) filters based on antiphase filters. We explore finite-register effects for unstable modes and provide bounds on the maximum TIIR filter length. In particular, we show that for unstable systems, the available dynamic range of the registers must be three times that of the data. Considerable computational savings over conventional FIR filters are attainable for a given specification of linear-phase filter. We provide examples of filter design. We show how to generate finite-length polynomial impulse responses using TIIR filters. We list some applications of TIIR filters, including uses in digital audio and an algorithm for efficiently implementing Kay's optimal high-resolution frequency estimator 相似文献
19.
Among the theory and design of oversampled nonuniform filter banks (NUFBs), most of the existing works only consider the cases with integer decimators, and up to now the issue with rational sampling factors has not been discussed yet. In this paper, we generalize the partial modulation technique to realize arbitrary rational frequency partitioning of oversampled NUFBs with highly desired linear-phase (LP) property. Further for the subbands with sampling factors violating the guard band restriction, a phase-modification scheme is derived to avoid uneliminable large aliasing and meanwhile preserving the LP characteristics of shifted analysis/synthesis filters. By using the proposed method, the design issue of LP oversampled NUFBs can be reduced to that of several prototypes, decreasing the design complexity largely. As illustrated by examples, the proposed algorithm is more general in terms of arbitrary rational decimation and thus has broad application prospects. 相似文献