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1、Matlab雷达回波数据模拟clear, hold offformat compactJ = sqrt(-l);close all% Get root file name for saving resultsfile=input(Enter root file name for data and listing files: ,s);% form radar chirp pulseT = 10e-6;% pulse length, secondsW = 10e6;% chirp bandwidth, Hzfs = 12e6;% chirp sampling rate, Hz; oversamp
2、le by a littlefprintf(nPulse length=%g microsecondsn,T/1e-6)fprintf(Chirp bandwidth = %g Mhzn,W/1e6)fprintf(Sampling rate = %g Msamples/secn,fs/1e6)s = git_chirp(T,W,fs/W); % 120-by-1 array plot(1e6/fs)*(0:length (s) -1),real(s) imag (s) title(Real and Imaginary Parts of Chirp Pulse) xlabel(time (us
3、ec)ylabel(amplitude)gridNp = 20;% 20 pulsesjkl = 0:(Np-1);% pulse index array,慢时间采样的序列，注意第一个PRI标记为0是为了慢时间起始时刻从零开始PRF = 10.0e3; PRI = (1/PRF);T_0 = PRI*jkl; g = ones(1,Np);% PRF in Hz% PRI in sec% relative start times of pulses, in sec% gains of pulsesT_out = 12 40*1e-6; % start and end times of rang
4、e window in sec， 这个就是接收 窗的时间宽度TrecT_ref = 0;% system reference time in usec T_ref = 0 指 T_0=0 时，r_at_T_0=ri ；当 T_0 = 0 时，r_at_T_0 = ri - vi*T_0(j)fc = 10e9;% RF frequency inHz; 10 GHz is X-bandfprintf(nWe are simulating %g pulses at an RF of %g GHz,Np,fc/1e9)fprintf(nand a PRF of %g kHz, giving a PR
5、I of %g usec.,PRF/1e3,PRI/1e-6) fprintf(nThe range window limits are %g to %g usec.n, .T_out(1)/1e-6,T_out(2)/1e-6)% Compute unambiguous Doppler interval in m/sec % Compute unambiguous range interval in metersvua = 3e8*PRF/(2*fc); %第一盲速 rmin = 3e8*T_out(1)/2;rmax = 3e8*T_out(2)/2;rua = 3e8/2/PRF;fpr
6、intf(nThe unambiguous velocity interval is %g m/s.,vua) fprintf(nThe range window starts at %g km.,rmin/1e3) fprintf(nThe range window ends at %g km.,rmax/1e3) fprintf(nThe unambiguous range interval is %g km.nn,rua/1e3)% Define number of targets, then range, SNR, and% radial velocity of each. The S
7、NR will be the actual SNR of the target in% the final data; it will not be altered by relative range.Ntargets = 4; del_R = (3e8/2)*( 1/fs )/1e3;% in kmranges = 2 3.8 4.4 4.4* le3;% in kmSNR= -3 5 10 7;%dBvels = -0.4 -0.2 0.2 0.4*vua;% in m/sec% From SNR, we compute relativeRCS using the idea that SN
8、R is proportional% to RCS/RA4. Students will be asked to deduce relative RCS.relRCS = (10.A(SNR/10). *(ranges.A4);rel_RCS = db(rel_RCS/max(rel_RCS)；power,)fprintf(nThere are %g targets with the following parameters:,Ntargets) for i = 1:Ntargetsfprintf(n range=%5.2g km, SNR=%7.3g dB, rel_RCS=%7.3g dB
9、, vel=%9.4g m/s,.ranges(i)/le3,SNR(i),rel_RCS(i),vels(i)end% Now form the range bin - pulse number data mapdisp(f) disp()disp(. forming signal component1)y = radar(s,fs,T O,g,T_out,T_ref,fc,ranges,SNR,vels); % y 是 337-by-20 的矩阵 add thermal noise with unit powerdispf. adding noise)%randnfseed,7734891
10、1);My,Ny = size(y);nzz = (l/sqrt(2)*(randn(My,Ny) + J*randn(My,Ny); % 产生方差为 1 的复高斯白噪严y = y + nzz;% create log-normal (ground) clutter with specified C/N and 具体 原理不清楚，需要时套用此格式即可！% log-normal standard deviation for amplitude, uniform phase% Clutter is uncorrelated in range, fully correlated in pulse #
11、disp(. creating clutter)CN = 20;% clutter-to-noise ratio in first bin (dB)SDxdB = 3;% in dB (this is NOT the sigma of the complete clutter)ncc= 10 .A(SDxdB*randn(My,Ny)/l0);ncc = ncc.*exp( J*2*pi*rand(My,Ny) );% Force the power spectrum shape to be Gaussiandisp(. correlating and adding clutter)G =ex
12、p(-(0:4),.A2/1.0);G = G;zeros(Ny-2*length(G)+l,l);G(length(G):-l:2);for i=l:My ncc(i,:)=ifft(G.*fft(ncc(i,:);end% rescale clutter to have desired C/N ratiopcc = var(ncc(:);ncc = sqrt( 10A(CN/10)/pcc)*ncc;% 10*logl0(var(ncc(:)/var(nzz(:) % check actual C/N% Now weight the clutter power in range for a
13、ssume RA2 (beam-limited) losscweight = T_out( 1 )*(T_out( 1) + (0:My-l)*(l/fs).A(-l);cweight = cweight*ones( 1 ,Np);ncc = ncc. *c weight; % var(ncc)可以看出20列clutter的方差均在30左右y = y + ncc;My,Ny=size(y);d=(3e8/2)*(0:My-1)*(1 /fs) + T_out(l)/le3; % T_out(l)/le3 是接收窗的起始时刻 plot(d,db(y,voltage) xlabel(distanc
14、e (km)ylabel(amplitude (dB)grid% Save the data matrix in specified file.% Save the student version in the mystery file.% Also save all parameter value displays in corresponding filedata_file=file,.iTiat; mystery_file=file, mys.mat;listing_file=fne打isHeval(9ave ,data_fne, J T W fs s Np PRF PRI T_out
15、fc vua,.1 rmin rmax rua Ntargets ranges vels SNR rel RCS y);eval(save -v6 mysteryflle/ J T W fs s Np PRF Tout fc y,);fld=fopen(listing_file；w,);fprintf(fid,rDESCRIPTION OF DATA IN FILE *,file,.mat AND file/ mys.matW*);fprintf(fid,rPulse length = %g microsecondsr,T/1 e-6); fprintf(fid,Chirp bandwidth = %g MhzrW/le6); fprintf(fid,Sampling rate = %g Msamples/secr,fs/1 e6);fprintf(fid,rWe are simulating %g pulses at an RF of %g GHz,Np,fc/le9); fprintf(fid,rand a PRF of
