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Design Method of 2-D Lattice Digital Filters Using the Genetic Algorithm
Hamada, Nozomu,Kishida, Masahiko 대한전자공학회 1994 ISPACS:Intelligent Signal Processing and Communica Vol.1 No.1
This paper proposes design method of 2-D lattice digital filters using the Genetic Algorithm(GA). By using the GA, they are derived directly from the desired frequency response, and 2-D stable nonseparable-denominator transfer functions can be obtained. In our method, ARMA transfer functions are designed by two algorithms. One is to optimize AR and MA parameters simultaneously, and the other is to search an optimal AR parameters with fixed MA parameters, and then search an optimal MA parameters separately. Both are done by the GA, and the simulation shows that they give the simillar results.
Design of Arbitrarily Rotated Frequency Response in Two-Dimensional Digital Filters
Hamada, Nozomu,Zhu, Jiemei 대한전자공학회 1994 ISPACS:Intelligent Signal Processing and Communica Vol.1 No.1
The aim of this paper is to present a design method of the zero phase two-dimensional (2-D) finite impulse response (FIR) filters having rotated frequency response of a given simple prototype FIR filter response. The first step of our approach is to design a prototype response by the filter with the impulse response whose domain is restricted within a circular region. This restriction prevents rotated impulse array to going out from the rectangular region. Then, the rotation of prototype impulse response, which ie given no more than on the rectangular lattice grid, causes the same rotation of prototype frequency response. The second step is the interpolation of the impulse response on the grids in the seine of the reconstruction of 2-D bandlimited discrete signals. Previous other methods for the rotation and the interpolation are compared with the proposed method. The obtained results for fan-type filter approximation by the proposed method show its validity.
Estimation of varying frequency by Gabor filters and Neural Network
Okano, Yasuhiro,Hamada, Nozomu 대한전자공학회 1996 APCCAS:Asia Pacific Conference on Circuits And Sys Vol.1 No.1
A method of varying frequency estimation using Gabor filter bank and neural network is proposed. This method consists of two phases. First phase is the feature extraction step which decomposes a given input signal into each frequency components using Gabor filter bank. Then, such components are treated as features in the frequency domain. Second phase is the estimation step which calculates instantaneous frequency from the first phase outputs using neural network. Neural network has the ability to estimate instantaneous frequency not only against artificial signal, but also against added noise signal. The aim of the proposed method is to estimate the varying frequency of non-stationary 1-D and 2-D (real) signal, where local frequency is assumed to vary smoothly.