ex9_9.m

MATLAB的程序

clear all;
close all;
clc
azi_num=2000;
fr=1000;
lamda0=0.05;
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=1*(sqrt(-2*log(d1)).*cos(2*pi*d2));
xq=2*(sqrt(-2*log(d1)).*sin(2*pi*d2));
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
xxi=conv(b,xi);
xxi=xxi(coe_num*2+1:azi_num+coe_num*2);
xxq=conv(b,xq);
xxq=xxq(coe_num*2+1:azi_num+coe_num*2);
vmuc=2;
xisigmac=std(xxi);
ximuc=mean(xxi);
xxi=(xxi-ximuc)/xisigmac;
xqsigmac=std(xxq);
xqmuc=mean(xxq);
xxq=(xxq-xqmuc)/xqsigmac;
xdata=xxi+j*xxq;
tmpdat=randn(1,azi_num);
[b,a]=butter(5,0.01);
sk_dat=filter(b,a,tmpdat);
sk_dat=sk_dat/std(sk_dat);
%%%%%%%%%%%%%%下面的程序解非线性方程%%%%%%%%%%%%%%%
max_z=6;
step=0.005;
table_z=0:step:max_z;
table_s=nonline_eq_sirp(table_z,vmuc);
for n=1:azi_num
    index=floor(abs(sk_dat(n))/max_z*length(table_z)+1);
    sk_dat(n)=table_s(index);
end
ydata=xdata.*sk_dat;
figure,subplot(2,1,1),plot(real(ydata)) title('K分布杂波时域波形，实部');
subplot(2,1,2),plot(imag(ydata)),title('K分布杂波时域波形，虚部');
%%%%%%%%求概率密度函数的参数%%%%%%%%%%%%%%%%%%
num=100;
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;
alpha=sqrt(std(xdata).^2./(2*vmuc));
th_val=lognpdf(xaxis1,xpdf1);

%xpdf1=getnpdf(abs(xdata),num,maxdat,mindat);
%xaxis1=mindat:(maxdat-mindat)/num:maxdat-(maxdat-mindat)/num;
%th_val=2*((xaxis1/(2*alpha)).^vmuc).*ESSELK((vmuc-1),xaxis1/alpha)./(alpha*gamma(vmuc));
figure,plot(xaxis1,xpdf1);
hold,plot(xaxis1,th_val,':r'),title('杂波幅度分布'),xlabel('幅度'),
ylabel('概率密度');
signal=ydata;
signal=signal-mean(ydata);
M=256;
psd_dat=pburg(real(signal),16,M,fr);
psd_dat=psd_dat/(max(psd_dat));
freqx=0:0.5*M;
freqx=freqx*fr/M;
figure,plot(freqx,psd_dat);
title('杂波频谱'),xlabel('频率（Hz）'),
ylabel('功率谱密度');
%%%%%%%% 理想高斯曲线%%%%%%%%%%%%
powerf=exp(-freqx.^2/(2*sigmaf.^2));
hold;
plot(freqx,powerf,':r');