logtest.m

对雷达杂波中正态对数分布的高斯谱杂波的仿真.

clear all; close all;
azi_num = 2000;
fr = 1000;
lamda0 = 0.05;
sigmav = 1.0;
sigmaf = 2*sigmav/lamda0;

randRes=spRand(0,1,azi_num);%生成两组互相独立的高斯随机数
%求滤波器系数
BT = .3; 
OF = 6;   
NT = 2;  
b = gaussfir(BT,NT,OF);
%生成高斯谱杂波
xxi = conv(b,randRes(1,:));
%去掉暂态响应
yyi=disZ(xxi,NT,OF,azi_num);

muc=10;     %中位值
sigmac=0.6; %形状参数

yyi=sigmac*yyi+log(muc);
ydata=exp(yyi);
figure,plot(ydata);

%仿真结果的概率密度
pdfRes=pdfPlot(abs(ydata),100);
%概率密度函数理论值
th_val=lognpdf(pdfRes(1,:),log(muc),sigmac);
figure(2)
plot(pdfRes(1,:),pdfRes(2,:),pdfRes(1,:),th_val,'r:');
title('杂波幅度分布');xlabel('幅度');ylabel('概率密度');

%求功率谱密度
signal = ydata;
signal = signal-mean(signal);%去直充分量
[psd_dat,freqx]=pburg(real(signal),16,128,fr);  %%%用Burg法估计功率谱密度
psd_dat=psd_dat/(max(psd_dat));      %归一化处理
powerf=exp(-freqx.^2/(2*sigmaf.^2)); %理想高斯谱曲线
figure(3)
plot(freqx,psd_dat,freqx,powerf,':r');
title('杂波频谱');xlabel('频率(Hz)');ylabel('功率谱密度');