$
clc
clear
close all
tic
set(0,'defaultfigurecolor','w')
%% ***************************²ÎÊýÉèÖÃ**************************** %%
% ÐźŲÎÊý
c = 3 * 1e+8; % ¹âËÙ
fc = 2 * 1e+9; % Ôز¨ÆµÂÊ
lambda = c / fc; % À״ﲨ³¤
Tr = 5 * 1e-6; % ÐźųÖÐøʱ¼ä
Br = 30 * 1e+6; % Ðźŵ÷Ƶ´ø¿í
Kr = Br / Tr; % µ÷ƵбÂÊ
alpha_os = 4.0; % ¹ý²ÉÑùÂÊ
Fr = alpha_os * Br; % ¿ìʱ¼ä²ÉÑùƵÂÊ
Nr = round( Fr * Tr ); % ¿ìʱ¼ä²ÉÑùµãÊý
disp(['ÀíÂÛ¾àÀë·Ö±æÂÊΪ£º', num2str( c / ( 2 * Br ) ), 'm']);
disp(['ÀíÂÛ²â»æ´ø´ø¿íΪ£º', num2str( c / ( 2 * Br ) * Nr ), 'm']);
disp('--------------------------------');
% Ä¿±ê²ÎÊý
position_target = [ 2997, 3000, 3050 ]; % Ä¿±êÏà¶ÔÀ×´ïµÄб¾à
sigma_target = [ 1, 1, 1 ]; % Ä¿±êµÄºóÏòÉ¢ÉäϵÊý
num_target = length( position_target ); % Ä¿±êÊýÁ¿
disp(['Ä¿±êAµÄʵ¼Ê¾àÀëΪ£º', num2str( position_target(1) ), 'm']);
disp(['Ä¿±êBµÄʵ¼Ê¾àÀëΪ£º', num2str( position_target(2) ), 'm']);
disp(['Ä¿±êCµÄʵ¼Ê¾àÀëΪ£º', num2str( position_target(3) ), 'm']);
disp('--------------------------------');
% ²â¾à²ÎÊý
Rmin = 1000;
Rmax = 7000;
Rwid = Rmax - Rmin; % ×î´ó²â¾à³¤¶È
Twid = 2 * Rwid / c; % »Ø²¨´°µÄ³¤¶È
Nwid = round( Fr * Twid ); % »Ø²¨ÐźŵIJÉÑùµãÊý
%% ***************************²â¾à·ÖÎö**************************** %%
% ·¢ÉäÐźÅ
t_tau_1 = linspace( 0, Nr-1, Nr ) / Nr * Tr;
sot = ( t_tau_1 <= Tr ) .* exp( 1j * pi * Kr * ( t_tau_1 - Tr/2 ).^2 );
% »Ø²¨ÐźÅ
t_tau_2 = linspace( 2*Rmin/c, 2*Rmax/c, Nwid );
srt_r = zeros( 1, Nwid );
for i = 1 : num_target
t_tau_3 = t_tau_2 - 2 * position_target(i) / c;
wr = abs( t_tau_3 ) <= Tr/2;
srt_target_r = sigma_target(i) * wr .* exp( 1j * pi * Kr * t_tau_3.^2 ) *...
exp( -1j * 4*pi * fc * position_target(i) / c );
srt_r = srt_r + srt_target_r;
end
figure
subplot(311)
plot( t_tau_1*1e+6, real(sot), 'b' );hold on;xlabel('ʱ¼ä/\mus');ylabel('·ù¶È');
plot( t_tau_2*1e+6, real(srt_r), 'r' );hold on;xlabel('ʱ¼ä/\mus');ylabel('·ù¶È');title('·¢ÉäÐźÅ&»Ø²¨ÐźÅ');
grid on;axis([0, 50, -4, 4]);
% Æ¥ÅäÂ˲¨
Nfft = 2^nextpow2( 2 * Nwid - 1 );
Srf_r = fft( srt_r, Nfft );
Hrf_2 = conj( fft( sot, Nfft ) );
Yrf_r = Srf_r .* Hrf_2;
yrt_r = fftshift( ifft( Yrf_r ) );
% ²¹Æ볤¶È
N0 = round( Nfft/2 - Nr/2 );
yrt_r_1 = yrt_r( N0 : N0 + Nwid - 1 );
% ¹éÒ»»¯
yrt_r_2 = 20 * log10( abs( yrt_r_1 ) ./ max( abs( yrt_r_1 ) ) + eps);
% SNR_n = 13;
% signal = awgn( yrt_r_1, SNR_n, 'measured' );
% ¾àÀë²âÁ¿
R_tau = t_tau_2*c/2;
R_peaks = findpeaks( yrt_r_2 );
R_peaks = sort( R_peaks, 'descend' );
R_dect_1 = R_tau( yrt_r_2 == R_peaks(1) );
R_dect_2 = R_tau( yrt_r_2 == R_peaks(2) );
R_dect_3 = R_tau( yrt_r_2 == R_peaks(3) );
R_dect = [ R_dect_1, R_dect_2, R_dect_3 ];
R_dect = sort( R_dect, 'ascend' );
disp(['Ä¿±êAµÄ²âÁ¿¾àÀëΪ£º', num2str( R_dect(1)), 'm']);
disp(['Ä¿±êBµÄ²âÁ¿¾àÀëΪ£º', num2str( R_dect(2)), 'm']);
disp(['Ä¿±êCµÄ²âÁ¿¾àÀëΪ£º', num2str( R_dect(3)), 'm']);
disp('--------------------------------');
subplot(312)
plot( R_tau, abs(yrt_r_1) );xlabel('¾àÀë/m');ylabel('·ù¶È');title('À×´ï»Ø²¨¾¹ýÂö³åѹËõ');
grid on;axis([0, 7500, 0, 800]);
subplot(313)
plot( R_tau, yrt_r_2 );xlabel('¾àÀë/m');ylabel('·ù¶È/dB');title('À×´ï»Ø²¨¾¹ýÂö³åѹËõ');
grid on;axis([0, 7500, -40, 1]);
% ¾Ö²¿·Å´ó
figure
subplot(211)
plot( R_tau, abs(yrt_r_1) );xlabel('¾àÀë/m');ylabel('·ù¶È');title('À×´ï»Ø²¨¾¹ýÂö³åѹËõ');
grid on;axis([2900, 3100, 250, 800]);
subplot(212)
plot( R_tau, yrt_r_2 );xlabel('¾àÀë/m');ylabel('·ù¶È/dB');title('À×´ï»Ø²¨¾¹ýÂö³åѹËõ');
grid on;axis([2900, 3100, -20, 1]);
%% -------------------------------------------------------------- %%
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