drfmfreq.m

此程序给出了不同情况的雷达距离测量仿真平台

% Program Plots Output Spectrum of DRFM
% Using I and Q Quadrature Channels
% -------------------------------------

clear;clf;clc;

% Sample Input Signal
 
N=2048;		% Samples
t=(1:N)/N;
fs=100;		% Hz
j=sqrt(-1);

% Generate input signals

B=[1 5];		% Quantizing Bits
num=[1 5];	% Number Input Signals

for bb=1:2;
for nn=1:2;
z=exp(j*2*pi*fs*t);

for k=1:num(nn)-1;
zz=exp(j*2*pi*fs*(1+.2*k)*t);
z=z+zz;end;

% Quantize Input Signals

M=2^(B(bb)-1);
for i=1:N;
xx(i)=(M*real(z(i)))/num(nn);
yy(i)=(M*imag(z(i)))/num(nn);
if xx(i)>0;x(i)=ceil(xx(i))/M;
      else x(i)=floor(xx(i))/M;end;
if yy(i)>0;y(i)=ceil(yy(i))/M;
      else y(i)=floor(yy(i))/M;end;end;
m=nn+2*(bb-1);
w(m,:)=x+j*y;

% Find Spectrum

X=fft(w(m,:),N);
X=fftshift(X);
Pxx=X.*conj(X);
Pxx=Pxx/max(Pxx);
Pz=10*log10(Pxx+1e-6);
P(:,m)=Pz';
end;
end;

% Plot DRFM Spectrum

f=(-N/2:N/2-1);

subplot(221);
plot(f,P(:,1));grid;
title(['DRFM Spectrum (Bits=',num2str(B(1)),',Sig=',num2str(num(1)), ')']);
axis([-500 500 -40 0]);
xlabel('Frequency - Hz');
ylabel('Amplitude - dB');

subplot(223);
plot(f,P(:,2));grid;
axis([-500 500 -40 0]);
xlabel('Frequency - Hz');
ylabel('Amplitude - dB');
title(['DRFM Spectrum (Bits=',num2str(B(1)),',Sig=',num2str(num(2)),')']);

subplot(222);
plot(f,P(:,3));grid;
axis([-500 500 -40 0]);
xlabel('Frequency - Hz');
ylabel('Amplitude - dB');
title(['DRFM Spectrum (Bits=',num2str(B(2)),',Sig=',num2str(num(1)),')']);

subplot(224);
plot(f,P(:,4));grid;
axis([-500 500 -40 0]);
xlabel('Frequency - Hz');
ylabel('Amplitude - dB');
title(['DRFM Spectrum (Bits=',num2str(B(2)),',Sig=',num2str(num(2)),')']);