matlab产生BPSK信号

matlab中每一个数据都可以看作是一次采样得到
采样频率决定了一个码元周期内有多少个数据点
载波频率决定了一个码元周期内有多少个载波

%edit by:yin
%time:2022_01_09
clc
clear

%% 基本参数
fs=200e6;
Ts=1/fs;
fc=25e6;
Rb=1.25e6;
Tb=1/Rb;
binary_code=[1 0 1 1 0 1 0 0 1 0 1];
len_code=length(binary_code);

%% 调制
bpsk=[];
t=0:Ts:(Tb-Ts);
for i=1:len_code
    if binary_code(i)==1
        bpsk=[bpsk,cos(2*pi*fc*t)];
    else
        bpsk=[bpsk,cos(2*pi*fc*t+pi)];  
    end
end
figure(1)
plot(bpsk)
%% 向调制信号加入高斯白噪声
SNR=30;
receive_sig=awgn(bpsk,SNR,'measured');
figure(2)
plot(receive_sig)

%% 解调
%乘法器
receive_T1=reshape(receive_sig,[160,11]);
receive_T2=cos(2*pi*fc*t)'.*receive_T1;
receive_T3=reshape(receive_T2,1,[]);
figure(3)
plot(receive_T3)
%低通滤波器
wp=20e6/(fs/2);
ws=40e6/(fs/2);
rp=3;
rs=20;
[n,wn]=buttord(wp,ws,rp,rs); 
[b,a]=butter(n,wn);
demodulation=filter(b,a,receive_T3);
figure(4)
plot(demodulation)