exe0705_1.m

Matlab程序为清华大学胡广书版信号处理的上机习题答案

%---------------------------------------------------------------
% exa0701_1
%---------------------------------------------------------------
clear all;

N=28;
b1=fir1(N,0.25,boxcar(N+1));  %用矩形窗作为冲激响应的窗函数
b2=fir1(N,0.25,hamming(N+1)); %用Hamming窗作为冲激响应的窗函数
%
M=128;
h1=freqz(b1,1,M);
h2=freqz(b2,1,M);
% 分别求两个滤波器的频率响应；
t=0:1:N;
f=0:1/M:1-1/M;
M1=floor(M*0.1);
M2=floor(M*0.15)+1;
M3=floor(M*0.3);
M4=floor(M*0.36)+1;
for k=1:M1
   hd(k)=0;
end
for k=M1+1:M2
   hd(k)=1;
end
for k=M2+1:M3
   hd(k)=0;
end
for k=M3+1:M4
   hd(k)=1;
end
for k=M4+1:M
   hd(k)=0;
end
f1=f(1:M/2)
hd1=hd(1:M/2)
f1= [0 0.1 0.1 0.15 0.15 0.3 0.3 0.36 0.36 0.5];
hd1=[0 0   1    1    0   0    1   1    0    0];
plot(f1,hd1);grid;
ylabel('abs(Hd)')
xlabel('omg/2pi');
xlim(0,0.5);

%figure(1);
%subplot(121);
%plot(f,abs(h1),'r-',f,abs(h2),'g-',f,hd,'-');grid;
%ylabel('abs(H)')
%xlabel('omg/2pi');