%--------------------------------------------------------------------------
% exa070903_remez_2.m, for example 7.9.3 and 7.4.2;
% to test remez.m and to design multi-band FIR filter;
%-------------------------------------------------------------------------
clear all;
clf; %清屏
clear; %清变量
w(1)=0.95;%0.95;
r(1)=0.80;
N=1024*2; %设置采样数据的个数
for t=1:N %计算产生系数w(t)和r(t)
w(t+1)=0.99*w(t)+0.01;
r(t+1)=0.99*r(t)+0.00995;
end
dt=1/8000; %设置采样频率
tt=0:dt:dt*N; %采样时间
%dis=2*(rand(size(tt))); %产生随机噪声数据
%y=1000*sin(2*pi*1000*tt)+8*dis; %产生加有噪声的正弦信号
y=wavread('single440Hz100db.wav');
y=y(:,1);
p0=10000/mean(y'*y); %计算信号的均值
%p0=1000/mean(y);
% 用切比雪夫最佳一致逼近设计线性相位多带FIR滤波器；
f=[0 .14 .18 .22 .26 .34 .38 .42 .46 .54 .58 .62 .66 1];
A=[1 1 0 0 1 1 0 0 1 1 0 0 1 1];
weigh=[8 1 8 1 8 1 8];
b=remez(128,f,A,weigh);
%
[h,w]=freqz(b,1,256,1);
hr=abs(h);
h=abs(h);
h=20*log10(h);
figure(1)
stem(b,'.');grid;
figure(2)
plot(w,h);grid;
qq=filter(w,h,y);
wvtool(y);
wvtool(qq);
