4、1)FIRfiltersareparticularlyusefulforapplicationswhereexactlinearphaseresponseisrequired.TheFIRfilterisgenerallyimplementedinanon-recursivewaywhichguaranteesastablefilter.FIR filter design essentially consists of twoparts(i)approximation problem (ii)(ii) realization
5、problemTheapproximationstagetakesthespecificationandgivesatransferfunctionthroughfoursteps.Theyareasfollows:(i)A desired or ideal response is chosen, usually in the frequency domain.(ii)An allowed class of filters is chosen (e.g.the length N for a FIR filters).(iii)A
6、 measure of the quality of approximation is chosen. (iv) A method or algorithm is selected to find the best filter transfer function.Therealizationpartdealswithchoosingthestructuretoimplementthetransferfunctionwhichmaybeintheformofcircuitdiagramorintheformofaprogram
7、.There are essentially three well-known methods for FIR filter design namely:Inthismethod,[Park87],[Rab75],[Proakis00]fromthedesiredfrequencyresponsespecificationHd(w),correspondingunitsampleresponsehd(n)isdeterminedusingthefollowingrelation(1) The window method (2)
8、 The frequency sampling technique (3) Optimal filter design methods The Window Method (2)(3)Ingeneral,unitsampleresponsehd(n)obt
