zabogaosi.m

共上载5个源码

%产生等多普勒等距离线杂波功率密度
%H为天线距离
%RCS为雷达反射截面积
%u为发射脉冲信号
%D为载机飞行俯冲角，Va为他的速度
%thata_r为天线波束中心方位角，phai_r为其入射角
%thata为方位角，phai为入射角
%fd为多普勒频率
%r为天线到波束中心与地面交点的距离
%jiajiao为波束中心到所计算单元入射角的角度，用以计算雷达在该方向的增益
%Pf为反射信号峰值功率
%S为反射的功率密度
%R为天线到目标单元的距离
%G为天线增益
%lambla为工作波长
%f为工作频率
clear;
clf;
rcs1=0.1;
rcs2=0.8;
H=1500;
dt=2*10^(-8);
t=10^(-5):dt:4*10^(-5);

%功率产生，即信号波形产生
Mx=350;Nx=20;
rate=0.4;
x=zeros(1,Mx*Nx);
x1=zeros(1,Nx);
x1(1:Nx*rate)=1;
for i=1:Mx
    x((i-1)*Nx+1:i*Nx)=x1;
end
u=x(1:length(t));
%t=2*10^(-5);
c=3*10^8;
fd=-1:1:200;
%fd=50;
Pf=100;
L=1;
f=10^8;
lambla=c/f;
Va=300;
D=0*pi/6;
thata_b=2.5*pi/180;
k1=log((2)^(1/2))/thata_b^2;
k2=1.3916/sin(0.5*thata_b);
N=length(t);
S=zeros(length(t),length(fd));
thata_r=1*pi/3;
phai_r=pi/5;
r=H/sin(phai_r);
for n=1:length(fd)
    for m=1:length(t)
        R=c*t(m)/2;
        %R=c*t(1)/2;
        if R<H;
            G=0;
        else
            %R=H/sin(pi/3);
            %cos(phai)=sqrt(R^2-H^2)/R;
            %sin(phai)=H/R;
            phai=asin(H/(R+eps));
            rcs=rcs1*sin(phai)+rcs2*exp(-((90-180*phai/pi)^2)/5);
            phai=abs(phai);
        
            %fd(n)=fd(1);
             KK=(lambla*fd(n)-2*Va*sin(D)*sin(phai))/(eps+2*Va*cos(D)*cos(phai));
             if KK>=1
                S(m,n)=0;
             else
                DD=sqrt(1-KK^2);
                thata=asin(DD);
                thata=thata;
                %A=(H*cot(phai_r))^2+(H*cot(phai))^2-2*H^2*(cot(phai_r)*cot(phai))*cos(thata-thata_r);
                A=(R)^2-(H)^2+r^2-H^2-2*sqrt(r^2-H^2)*sqrt(R^2-H^2)*cos(thata-thata_r);
                jiajiao=acos((R^2+r^2-A)/(2*R*r));
                %A=(R)^2-(H)^2+r^2-H^2-2*sqrt(r^2-H^2)*sqrt(R^2-H^2)*cos(thata-thata_xin);
                %jiajiao=acos((R_xin^2+Rd^2-A)/(2*Rd*R_xin));
                % if jiajiao>=pi;
                     %jiajiao=abs(jiajiao-pi);
                %else
                     %jiajiao=abs(jiajiao);
                     %jiajiao=0;
                % end
                KKK(m,n)=jiajiao;
                 if jiajiao<0*pi/180;
                     G=exp(-k1*jiajiao^2);
                 else
                     G=((1+cos(jiajiao+eps))./2).*((sin(k2.*sin(jiajiao+eps)))./(k2*sin(jiajiao+eps)));
                 end
             G=abs(G);
             G1(m,n)=G;
             Pt=Pf*u(m);
             Pt=1;
             S(m,n)=(Pt*lambla^3*G^2*rcs*L)/(eps+(4*pi)^3*R^3*Va*cos(D)*cos(phai*0.999)*DD);
             end
        end
    end
end


%画三维图
%

figure(1)
XX=ones(1,length(t))'*fd;
YY=t'*ones(1,length(fd));
mesh(XX,YY,10*log10(abs(S+eps)))
title('地面杂波图')
%mesh(abs(S))

figure(2)
zt=sum(S');
plot(abs(zt));