【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