matlab低通滤波器设计.txt

设计一个数字FIR低通滤波器

wp=0.2*pi;ws=0.3*pi; 
tr_width=ws-wp; 
M=ceil(6.6*pi/tr_width)+1 
M=67 
n=[0:1:M-1]; 
wc=(ws+wp)/2; 
hd=ideal_lp(wc,M); 
w_ham=(hamming(M))'; 
h=hd.*w_ham; 
[db,mag,pha,grd,w]=freqz_m(h,[1]); 
delta_w=2*pi/1000; 
Rp=-(min(db(1:1:wp/delta_w+1))); 
Rp=0.0394 
As=-round(max(db(ws/delta_w+1:1:501))) 
As=52 
subplot(1,1,1) 
subplot(2,2,1);stem(n,hd);title('Ideal Impulse Response') 
axis([0 M-1 -0.1 0.3]);xlabel('n');ylabel('hd(n)') 
subplot(2,2,2);stem(n,w_ham);title('Hamming Window') 
axis([0 M-1 0 1.1]);xlabel('n');ylabel('w(n)') 
subplot(2,2,3);stem(n,h);title('Actual Impulse Response') 
axis([0 M-1 -0.1 0.3]);xlabel('n');ylabel('h(n)') 
subplot(2,2,4); plot(w/pi,db); title('Magnitude Response in dB');grid 
axis([0 1 -100 10]);xlabel('frequency in pi units');ylabel('Decibels')