QMF group design method of two-channel IIR based on all-pass filter
A technology of all-pass filter and design method, applied in the network, impedance network, electrical components and other directions using active components, can solve the problem of not considering the phase error of the all-pass filter, the stop-band error of the low-pass filter, the complex calculation, etc. problem, to achieve the effect of ensuring degrees of freedom, accurate coefficients, and good performance indicators
Active Publication Date: 2020-03-27
HANGZHOU DIANZI UNIV
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This algorithm borrows the method of designing FIR with equal ripples to get the all-pass filter, but its calculation is extremely complicated, and this algorithm does not consider the phase error of the all-pass filter and pure delay synthesis and the resistance of the obtained low-pass filter. with error
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[0044] The present invention will be further described below in conjunction with accompanying drawing.
[0045] The specific steps of the improved two-channel IIR quadrature image filter bank design method based on the all-pass filter are as follows:
[0046] Step 1. According to the design requirements, determine the number of frequency points L on the full frequency band and the order N of the two all-pass filters 1 and N 2 , The pass-band cut-off frequency ω of the low-pass filter in the analysis filter p , the stopband cutoff frequency ω s , let the iteration initial coefficient k=0, the k-th all-pass filter coefficient a i (k)=0, initial weighted value W i =1, i=1,2; where N 1 =N 2 +1;
[0047] Step 2, determining the actual phase error of the all-pass filter.
[0048] 2.1. Determining the ideal phase of the all-pass filter
[0049] The ideal phase of the all-pass filter is satisfied on the frequency band of ω∈[0,π]: when the phase of the IIR filter satisfies ω=0, ...
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The invention discloses a QMF group design method of a two-channel IIR based on an all-pass filter. Aiming at the problem of minimum maximization of the phase of the all-pass filter, by determining the phase error and the appropriate weighted value of the all-pass filter, the obtained nonlinear optimization target is subjected to first-order Taylor expansion and converted into a linear problem, and the optimal coefficient of the all-pass filter is obtained. According to the method, the phase of each all-pass filter is optimized, so that each sub-filter through which the signal passes is ensured to have a more approximately linear phase, the possibility of phase distortion is reduced, and the expected design target is achieved. The biggest improvement of the method lies in that the coefficient of each all-pass filter is determined separately, joint design is not needed any more, the obtained coefficients are more accurate and do not influence one another any more, and a certain degree of freedom of design is guaranteed; and meanwhile, it is ensured that no phase distortion exists in the signal in any time period, so that reconstruction is achieved, and a better performance index canbe obtained in limited iteration times.
Description
technical field [0001] The invention belongs to the technical field of digital signal processing, and in particular relates to an improved design method of a two-channel IIR quadrature image filter bank based on an all-pass filter. Background technique [0002] Over the past few decades, digital signal processing systems have gradually replaced analog systems, and today, digital signal processing systems can be found in a variety of different devices, such as mobile communication systems, consumer electronics and automotive electronics products, or hearing aids. A decisive advantage of digital signal processing is that a system can be realized with digital signal processing that cannot or hardly can be realized with analog processing. An important component of many digital signal processing algorithms are filters and their series connection as filter banks. Filter banks are mainly used for spectral analysis of signals, as cross-multiplexers, or to process sub-band frequenc...
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IPC IPC(8): H03H11/04
CPCH03H11/0466
Inventor 王浩李祥振赵知劲赵晨子李伟琪靳一
Owner HANGZHOU DIANZI UNIV