fftfila.m

此程序给出了不同情况的雷达距离测量仿真平台

% FFT Doppler Filter Response
% ---------------------------

clf;clc;clear;

% Define Frequency Vector

N=32;			% FFT Points
PRF=2000;		
T=1/PRF;
fd=(1/(2*T))*(0:1024-1)/1024;

% Compute Filter Response - Uniform Weights

for k=1:16;
x=2*pi*fd*T/2+1e-10;
H=sin(N*x)./sin(x-((k-1)*pi/N));
Hd=H.*H;
Pdb(:,k)=10*log10(Hd'/(N^2)+1e-2);
end;

% Plot Filter Response 

subplot(211);
plot(fd,Pdb,'k');grid;
xlabel('Frequency - Hz');
ylabel('Amplitude - dB');
title(['FFT Filter Response - Uniform Window']);
axis([ 0 1000 -20 0]);

% Compute Filter Response - Hanning Weights

a=.5;

for k=1:16;
x=2*pi*fd*T/2+1e-10;
H(k,:)=sin(N*x)./sin(x-(k-1)*pi/N);
end;

for l=2:15;
Hw(l,:)=H(l,:)-a*(H(l+1,:)+H(l-1,:));
Hd(l,:)=Hw(l,:).*Hw(l,:);
Pldb(:,l)=10*log10(Hd(l,:)'/(N^2)+1e-6);
end;

% Plot Filter Response

subplot(212);
plot(fd,Pldb,'k');grid;
xlabel('Frequency - Hz');
ylabel('Amplitude - dB');
title(['FFT Filter Response - Hanning Weighting']);
axis([ 0 1000 -50 0 ]);