clear
close all
clc

N=45;
wn=[0.3,0.5];%截止频率
window=hanning(N+1); %计算长度为N的汉宁窗
b=fir1(N,wn,window); %N是阶数,wn是截止频率
[H,w]=freqz(b); 

subplot(2,1,1);plot(w/pi,20*log10(abs(H)));grid; xlabel('归一化频率');ylabel('幅度');title('幅频响应'); 
subplot(2,1,2);plot(w/pi,angle(H));grid; xlabel('归一化频率');ylabel('相位');title('相位响应');

clear
close all
clc

%矩形窗N=15

% N=input('请输入 N 的值\n');wn=[0.3,0.5];
% b=fir1(N,wn,boxcar(N+1)); 
% [H,w]=freqz(b,1,512); 
% subplot(2,1,1);plot(w/pi,20*log10(abs(H)));grid; xlabel('归一化频率');ylabel('幅度');title('幅频响应'); 
% subplot(2,1,2);plot(w/pi,angle(H));grid; xlabel('归一化频率');ylabel('相位');title('相频响应');


%布莱克曼窗：（N=15 时）
% 
N=input('请输入 N 的值\n');
wn=[0.3,0.5]; 
window=blackman(N+1); 
b=fir1(N,wn,window); 
[H,w]=freqz(b); 
subplot(2,1,1);plot(w/pi,20*log10(abs(H)));grid; xlabel('归一化频率');ylabel('幅度');title('幅频响应'); 
subplot(2,1,2);plot(w/pi,angle(H));grid; xlabel('归一化频率');ylabel('相位');title('相频响应');