【转】成型滤波与匹配滤波的MATLAB实现

转载自：https://blog.csdn.net/yuan1164345228/article/details/45919315

 

Fd=1;  
Fs=8;   
Delay=3;   
R=0.5;   
[yf,tf]=rcosine(Fd,Fs,\'fir/sqrt\',R,Delay);  
figure(1);
plot(yf); grid;title(\'根升余弦滤波器时域波形\')
x=randint(100,1)*2-1;%原始输入信号为+1，-1码    
xt=zeros(1,800);    
xt(1:8:end)=x; %%插值后信号
y1=filter(yf,tf,xt); %%成型滤波  
y2=filter(yf,tf,y1); %%用与发送端相同的根升余弦匹配滤波
yt=y2((size(yf)+1)/2:8:end);%%匹配滤波后抽取        
figure(2);    
stem(x(1:40)); grid;title(\'原始信号输出\');
figure(3);
plot(y1(1:100));grid;title(\'成型信号输出\');
figure(4);
plot(y2(1:100));grid;title(\'匹配滤波信号输出\');
figure(5);    
stem(yt(1:40)); grid;title(\'抽取后信号输出\') ;

　　

滤波器的截止频率是Fd/2；Fs/Fd是内插倍数；其频响可以由滚降系数和窗长(FIR阶数)确定。 
delay * (Fs / Fd) * 2 + 1就是滤波器的阶数