sc.m

不适用matlab自带滤波器函数的fir低通滤波器设计

start=[1 0 0 1 0 1 0 0 0 0 0 1];

p=seq(start);

n=numel(start);

N=2^n-1;

n=0:1:(N-1);

bpskseq=bpsk(p);
figure(1); plot(n,bpskseq);

for t=1:256
sd(t)=bpskseq(t);
end

figure(1); stem(1:length(sd),sd);

fbpsk=freqz(bpskseq,[1],1000);
g=0:1:length(fbpsk)-1;
figure(2); plot(2.*g/length(fbpsk),abs(fbpsk));



for k=1:2    
    x1(1)=bpskseq(1);    
    for i=2:length(bpskseq)    
        x1(i)=bpskseq(i)-bpskseq(i-1);        
    end    
    bpskseq=x1;    
end

x2=upsample(x1,7);

for k=1:2
    x(1)=x2(1);   
    for i=2:length(x2)    
        x(i)=x(i-1)+x2(i);        
    end 
    x2=x;    
end

xxx=fft(x)

long=0:length(xxx)-1;

figure(3); plot(2.*long/length(xxx),abs(xxx))

[n,wn,beta]=kaiserord([0.45 0.55]*pi,[1 0],[0.01,0.01],2*pi)

hhh=fir1(n-1,wn,kaiser(n,beta));

figure(4); stem(0:length(hhh)-1,hhh);

t=upsample(x,2);
x=conv(t,hhh);
t=upsample(x,2);
y=conv(t,hhh);
t=upsample(y,2);
z=conv(t,hhh);

finish=fft(z);
n=0:1:length(finish)-1;
figure(5); plot(n,(abs(finish)));