bpsk.txt

本程序很好的实现了BPSK调制解调技术对基带信号的调制和解调仿真

% BPSK

fc=20;% carrier frequency

t=0:0.01:100-0.01;% time 

m=randint(1,100,[0 1]);%

m=2*(m-0.5);

m=repmat(m,100,1);

m=reshape(m,1,10000);%baseband signal

if 0  %spectrum

    fm=fft(m,10000,2);%fft=fast forier transforming

    fm=abs(fm).^2;

    f=0:0.01:100-0.01;

    plot(f(1:5000),fm(1:5000));

    grid on;

    xlabel('frequency [Hz]');

end

s=m.*cos(2*pi*fc*t);%pi=3.1416 s:modulated signal

if 0%received baseband signal sprectrum

    fs=fft(s,10000,2);

    fs=abs(fs).^2;

    plot(f(1:5000),fs(1:5000));

    grid on;

    xlabel('frequency [Hz]');

end

r=s.*cos(2*pi*fc*t)*2;

frA=fft(r,10000,2);

if 1

    fr=abs(frA).^2;

    plot(f(1:5000),fr(1:5000));

    grid on;

    xlabel('frequency [Hz]');

end

%% LPF (start)

fn=frA;

fn(1,2000:8000)=0;

n=ifft(fn,10000,2);

n=real(n);

%%  LPF(end)

if 0

    plot(t,n,t,m);

    grid on;

    xlabel('time [s]');

    legend('received signal','transmitted signal',4);

end

if 1% show received-baseband-signal spectrum

    fn=fft(n,10000,2);

    fn=abs(fn).^2;

    plot(f(1:5000),fn(1:5000));

end