sim.m

实现对自适应波束形成SIM算法的仿真

clear,clc
fs=400000;
fd1=100;
fd2=400;
f01=200000;
f02=200000+2000;
j=20;                       %信噪比
k=4000;                    %采样点数   
n=1:k;
m=8;                         %阵元个数
dtheta=0.5;
   
a1=2+4/pi*[cos(2*pi*fd1*n/fs)-1/3*cos(6*pi*fd1*n/fs)+1/5*cos(10*pi*fd1*n/fs)];  %基带信号
%subplot(2,1,1);
%plot(a1);
x1=cos(2*pi*f01*n/fs+pi/4); % 调制信号
%subplot(2,1,2);
%plot(x1);

s1=10*a1.*x1;                   %已调信号
a2=2+4/pi*[cos(2*pi*fd2*n/fs)-1/3*cos(6*pi*fd2*n/fs)+1/5*cos(10*pi*fd2*n/fs)];
x2=cos(2*pi*f02*n/fs+pi/3);
s2=a2.*x2;
S=[s1;s2];
theta1=40;     %信号
theta2=-20;    %干扰
b1=[1 exp(-i*pi*sin(pi*theta1/180)) exp(-i*2*pi*sin(pi*theta1/180)) exp(-i*3*pi*sin(pi*theta1/180)) exp(-i*4*pi*sin(pi*theta1/180)) exp(-i*5*pi*sin(pi*theta1/180)) exp(-i*6*pi*sin(pi*theta1/180)) exp(-i*7*pi*sin(pi*theta1/180))].';
b2=[1 exp(-i*pi*sin(pi*theta2/180)) exp(-i*2*pi*sin(pi*theta2/180)) exp(-i*3*pi*sin(pi*theta2/180)) exp(-i*4*pi*sin(pi*theta2/180)) exp(-i*5*pi*sin(pi*theta2/180)) exp(-i*6*pi*sin(pi*theta2/180)) exp(-i*7*pi*sin(pi*theta2/180))].';
A=[b1 b2];
N=sqrt(j)*randn(m,k);
X=A*S+N;

R=(X*X')/k;        %自相关矩阵 
r=(X*s1')/k;       %互相关矩阵
w=inv(R)*r;         %权向量


L=180/dtheta+1;
for ii=1:1:L
theta=-90+ii*dtheta;
b=[1 exp(-i*pi*sin(pi*theta/180)) exp(-i*2*pi*sin(pi*theta/180)) exp(-i*3*pi*sin(pi*theta/180)) exp(-i*4*pi*sin(pi*theta/180)) exp(-i*5*pi*sin(pi*theta/180)) exp(-i*6*pi*sin(pi*theta/180)) exp(-i*7*pi*sin(pi*theta/180))]';
PSMI(ii)=w.'*b;
end
p=abs(PSMI).^2/(max((PSMI).^2));

pdb=10*log10(p);
plot(-90:dtheta:90,pdb),ylabel('增益(dB)'),xlabel('干扰=-20°,信号=40°');
grid on;
hold on;            % 启动图形保持功能