radar return signal picturization

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Palguna Gopireddy
Palguna Gopireddy il 25 Nov 2021
I have a radar synthetic aperture radar whose return signal is taken for a point target at 7500m. I am using LFM wave with duratio 6e-06 sec.
Iam unable to plot the SAR returns shown like in the textbook (DSP techniques and applications by Bu-Chan Wang)
The author said he plotted the SAR returns taking 1 out out every thirty rows from 563 rows. The picturization he has shown is
My question is he has plotted it in 2D space, x axis the signal, y-axis 1 out of every 30 signals of 563 signals. Then how can we see the amplitude in y axis. The signal has to be stright line, since the amplitude would be z-axis( out of page or inwords the page).
Lets say he has plotted the signals ampltude in y axis for these 19 signals (1 out of 30 in 563). All the 19 signals amplitudes are more or less same values. Then the signals should collide in the picture. But it is not the case.
Can anyone explain how to plot like this? . I have plotted adding 1 to the consicutive signals amplitude with the code
o=1;
Taz=zeros(563,181);
for ta=[-281:281]
Taz(o,:)=ta;
o=o+1;
end
The graph picture came like this
Is it correct way of plotting or not?
Is there any other function or way we can plot like in the textbook figure shown?
Please somebody explain this?
Thanks in advance
  4 Commenti
Palguna Gopireddy
Palguna Gopireddy il 31 Gen 2022
Here is the code used.
fc=1e+10;
c=3e+08;
lambda=c/fc;
Tp=6.033e-06;
alpha=4e+12;
R0=7500;
y0=112.4;
fs=30e+06;
Range_bw=alpha*Tp;
V=200;
beta=-(2*V^2)/(R0*lambda);
fPRF=500;
L=1;
Range_sample_spacing=c/fs;
bw_3dB=lambda/L; % in degrees
Az_sample_spacing=V/fPRF;
Ls=R0*bw_3dB;
Doppler_bw=2*V/L;
Naz=round(Ls/Az_sample_spacing);
Nr=round(fs*Tp);
R1=R0/cos(0.5*bw_3dB);
R3=R1;
Nr_FFT=2^ceil(log2(Nr));
Naz_FFT=2^ceil(log2(Naz));
Ta=224.8/V;
c=3e+08;
dt=1/fs;
n = round(Tp*fs);
t = [-n/2:n/2-1]*dt;
t=repmat(t,Naz,1);
ui=[0.1:Az_sample_spacing:224.9]';
delay=(2*sqrt(((ui-y1).^2)+(R0^2)))/c;
delay=repmat(delay,1,n);
phase=(-2*pi*fc*delay)+(pi*alpha).*(t-delay).^2;
rx_signal=exp(1i*phase);
q=1;
for k=1:30:563
z=q+real(rx_signal(k,:));
plot(fftshift(z,2).');
hold on
q=q+3;
end
hold off
Benjamin Thompson
Benjamin Thompson il 31 Gen 2022
In the insert section of the menu there is a button with a paperclip picture. Use this to attach sample data in MAT format or M format.

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