examp52.m

来自「ADSP TOOLBOX: Version 2.0 and gui m-file」· M 代码 · 共 20 行

clc,echo on 
%EXAMPLE 52 
n=-20:20; % Create a DT index 
Fc=0.2; h=2*Fc*sinc(2*Fc*n);         % Create impulse response 
a=[zeros(1,20) 1 zeros(1,20)];       % Denominator array of DTFT 
f=(-200:199)/400;w=2*pi*f;           % Frequency array (F=-0.5 to F=-0.5) 
HI=(abs(f)<=0.2);                    % Ideal Filter Spectrum,  $F_{C}=0.2$ 
HT=abs(freqz(h,a,w));                % Spectrum of truncated h[n] 
f1=f+0.5;                            % Frequency array (F=0 to F=1) 
x=sinc(41*f1)./sinc(f1);Wd=41*x;     % Dirichlet kernel 
x=sinc(20*f1)./sinc(f1);Wf=20*x.*x;  % Fejer kernel 
HD=convp(HI,Wd)/400;                 % Periodic conv with Dirichlet kernel
HF=convp(HI,Wf)/400;                 % Periodic conv with Fejer kernel
plot(f,HI),grid,pause(2)             % Spectrum of ideal filter
plot(f,HD),grid,pause(2)             % and windowed by Dirichlet
plot(f,HF),grid,pause(2)             % and windowed by Fejer
plot(f,HT),grid                      % Spectrum of truncated h[n]
echo off %end of example