Dear Pritam: Comb filters are very simple, I don't think you should need any special software to create them. They are used precisely because they are simple, and have small, integer coefficients. Some standard DSP filter analysis functions, such as are in MATLAB's Signal Processing Toolbox and Filter Design Toolbox, should do. To decimate or interpolate by N, the kth order comb filter, in the z-domain, is simply: ( Summation of i from 0 to N-1 of z^i)^k For decimation/interpolation by N=2, this means that the filter coefficients are the binomial expansion coefficients; there will be k+1 coefficients, and the ith coefficient is nchoosek(k,i-1). Usually for a comb filter design, you would do multiple stages of decimation/interpolation and use small decimation/interpolation ratios N for maximum efficiency. Sincerely, Glen Ragan |
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