The aim of the experiment was to design a Digital Filter using windowing method. Code was developed in Scilab, which asked user to enter Ap, As,wp & ws. Depending upon the value of As, windowing function among Rectangular, Bartlet, Hamming, Hanning & Blackman was selected & order of the filter was computed using Transition width of windowing function.
Thus, Phase response varies linearly with frequency, and no distortion is observed at the output of the filter. Output is same as input delayed by some constant.
How to choose any window function ?
ReplyDeleteBlackman window function is considered as the most suitable window function as it has the highest stopoband attenuation.
ReplyDeleteWhat is the effect of windowing on W e^(jw)?
ReplyDeleteDiscontinuities in H(e^jw) are converted into transition bands between values on either sides of discontinuity
ReplyDeleteWindow function should be selected after analyzing frequency spectrums of the output for all windowing methods.Side lobes in stopband should be reduced.
ReplyDeleteGenerally rectangular window is not preferred due to its low value of stop band attenuation.
ReplyDeletewindow selection is done upon requirement of passband attenuation
ReplyDeleteThe trick is to select the window function that will give a filter with the correct transition width and attenuation in stopband.
ReplyDeleteFIR filter is designed by truncating infinite samples of hd[n] by using window function. Examples of window function are rectangular, barnet hamming, hanning and blackman
ReplyDeleteAttenuation of the side lobes is an important factor.
ReplyDeleteWhy a rectangular window is not prefered in filter design ?
ReplyDeleteRectangular window is not preferred because of low stop band attenuation
ReplyDelete