dfcm.m

此程序给出了不同情况的雷达距离测量仿真平台

% Dicke-Fix Countermeasure
% -------------------------

clf;clc;clear;

% Define Time Vector

tmax=.06;N=1024;
t=tmax*(1:N)/N;

% Sample Frequency

fs=N/tmax;

% Generate Modulated Signal

x=cos(2*pi*256*t)+3*square(2*pi*32*t).*cos(2*pi*256*t);

% Plot Waveform

subplot(2,2,1)
plot(t,x);grid;
xlabel('Time - sec');ylabel('Volts');
title(['Jam Waveform']);

% Limit Signal To Clip Level k

k=1;
for i=1:N;
   y(i)=x(i);
   if x(i)>k;y(i)=k;end;
   if x(i)<-k;y(i)=-k;end;
end;

% Plot Limited Waveform

subplot(2,2,3);
plot(t,y);grid;
xlabel('Time - sec');ylabel('Volts');
title(['Clipped Waveform']);

% Find x and y for M steps

M=64;A=[];B=[];
for i=1:M;
A=[A x];B=[B y];end;
x=A;y=B;

% Extend t vector

N=N*M;
t=M*tmax*(1:N)/N;

% Find Power Spectrums

Y=fft(y);X=fft(x);
Py=Y.*conj(Y);Px=X.*conj(X);
Py=fftshift(Py);Px=fftshift(Px);

% Select Central Frequency Axis

Px(3*N/4+1:N)=[];
Px(1:N/4)=[];
Py(3*N/4+1:N)=[];
Py(1:N/4)=[];
fax=fs*(-N/4:N/4-1)/N;

% Normalize Amplitude

Px=Px/max(Px);
Py=Py/max(Py);
Pxdbm=30+10*log10(Px+1e-6);
Pydbm=30+10*log10(Py+1e-6);


% Plot Power Spectrums

subplot(2,2,2);plot(fax,Pxdbm);grid;
xlabel('Frequency - Hz');
ylabel('Power - dbm');
title(['Power Spectrum']);
axis([0 ,600 ,-30,40]);
subplot(2,2,4);plot(fax,Pydbm);grid;
xlabel('Frequency - Hz');
ylabel('Power - dbm');
title(['Jammed Spectrum']);
axis([0,600,-30,40]);

end