duishuzhengtai.m

对数正态分布的杂波程序 比较经典的有所改动

clear all;close all
azi_num=2000;%雷达的回波贞数
fr=1000;%脉冲频率
lamda0=0.05;%波长
sigmav=1.0;
sigmaf=2*sigmav/lamda0;
rand('state',sum(100*clock));
d1=rand(1,azi_num);
rand('state',7*sum(100*clock)+3);
d2=rand(1,azi_num);
xi=2*sqrt(-2*log(d1)).*cos(2*pi*d2);%^正交独立的高斯序列
coe_num=12;
for n=0:coe_num
    coeff(n+1)=2*sigmaf*sqrt(pi)*exp(-4*sigmaf^2*pi^2*n^2/fr^2)/fr;
end
for n=1:2*coe_num+1
    if n<=coe_num+1
        b(n)=1/2*coeff(coe_num+2-n);
    else
        b(n)=1/2*coeff(n-coe_num);
    end
end
%高斯仆杂波
xxi=conv(b,xi);
xxi=xxi(coe_num*2+1:azi_num+coe_num*2);%去掉暂态响应
xsigmac=std(xxi);
xmuc=mean(xxi);
yyi=(xxi-xmuc)/xsigmac;
muc=10
sigmac=0.6;
yyi=sigmac*yyi+log(muc);
ydata=exp(yyi);
figure(1),
subplot(2,1,1),plot(ydata);title('杂波时域波形');
num=100;%求概率密度
maxdat=max(abs(ydata));
mindat=min(abs(ydata));
NN=hist(abs(ydata),num);
xpdf1=num*NN/((sum(NN))*(maxdat-mindat));
xaxis1=mindat:(maxdat-mindat)/num:maxdat-(maxdat-mindat)/num;
th_val=lognpdf(xaxis1,xpdf1);
figure(1);subplot(2,1,2),plot(xaxis1,xpdf1);
hold,plot(xaxis1,th_val);title('杂波幅度分布');xlabel('幅度');ylabel('概率密度');
signal=ydata;
signal=signal-mean(signal);
figure(4);M=128;
psd_dat=pburg(real(signal),16,M,fr);
psd_dat=psd_dat/(max(psd_dat));%归一化
freqx=0:0.5*M;
freqx=freqx*fr/M;
plot(freqx,psd_dat);title('杂波频谱');xlabel('HZ');ylabel('密度');
%理想曲线
powerf=exp(-freqx.^2/(2*sigmaf.^2));
hold;plot(freqx,powerf);