DM54X平台上的FIR低通滤波器设计与实现

具体参数：
带通范围：0.35pi－0.8pi，1dB;阻带为<0.2pi,>0.8pi,60dB

M程序：
ws1 = 0.2*pi; wp1 = 0.35*pi;
wp2 = 0.65*pi; ws2 = 0.8*pi;
As = 60;
tr_width = min((wp1-ws1),(ws2-wp2))
M = ceil(11*pi/tr_width) + 1 %;M=68
n=[0:1:M-1];
wc1 = (ws1+wp1)/2; wc2 = (wp2+ws2)/2;
hd = ideal_lp(wc2,M) - ideal_lp(wc1,M);
w_bla = (blackman(M))';
h = hd .* w_bla;
[db,mag,pha,grd,w] = freqz_m(h,[1]);
delta_w = 2*pi/1000;
Rp = -min(db(wp1/delta_w+1:1:wp2/delta_w)) % Actua; Passband Ripple
As = -round(max(db(ws2/delta_w+1:1:501))) % Min Stopband Attenuation

% plots
figure(1);
subplot(2,2,1); stem(n,hd); title('Ideal Impulse Response')
axis([0 M-1 -0.4 0.5]); ylabel('hd(n)')
subplot(2,2,2); stem(n,w_bla);title('Blackman Window')
axis([0 M-1 0 1.1]); ylabel('w(n)')
subplot(2,2,3); stem(n,h);title('Actual Impulse Response')
axis([0 M-1 -0.4 0.5]); ylabel('h(n)')
subplot(2,2,4);plot(w/pi,db);
title('Magnitude Response in dB');grid;