afd_butt.m

MATLAB信号处理扩展函数,用于信号处理的扩展函数

function [b,a]=afd_butt(Wp,Ws,Rp,As);%Butterworth低通滤波器原型设计
         if Wp<=0
             error('Passband edge must be larger than 0')
         end
         if Ws<=Wp
             error('Stop band edge must be larger than Passband edge')
         end
         if (Rp<=0)|(As<0)
             error('PB ripple edge must be larger than Passban edge')
         end
         N=ceil((log10((10^(Rp/10)-1)/(10^(As/10)-1)))/(2*log10(Wp/Ws)));
         fprintf('\n***Butterworth Filer Order=%2.0f\n',N)
         OmegaC=Wp/((10^(Rp/10)-1)^(1/(2*N)));
         [b,a]=u_buttap(N,OmegaC);