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Highlights from
Digital Signal Processing Using MATLAB

Digital Signal Processing Using MATLAB

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21 Aug 2002 (Updated )

Companion Software

ex071000.m
% Chapter 07: Example 7.10 Bandpass filter design - Blackman window

%

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

subplot(1,1,1);

subplot(2,2,1); stem(n,hd); title('Ideal Impulse Response')

axis([0 M-1 -0.4 0.5]); xlabel('n'); ylabel('hd(n)')

subplot(2,2,2); stem(n,w_bla);title('Blackman 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 -0.4 0.5]); xlabel('n'); ylabel('h(n)')

subplot(2,2,4);plot(w/pi,db);%set(gca,'FontName','cmr12');

title('Magnitude Response in dB');grid;

xlabel('frequency in pi units'); ylabel('Decibels')

axis([0 1 -150 10]); 

set(gca,'XTickMode','manual','XTick',[0,0.2,0.35,0.65,0.8,1])

set(gca,'YTickMode','manual','YTick',[-60,0])

set(gca,'YTickLabelMode','manual','YTickLabels',['60';' 0'])

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