santhosh SAR Signal processing Two dimensional energy spread in range and azimuth Goal to focus into single pixel Range dimension spread duration of chirp transmitted Azimuth dimension spread duration of synthetic aperture ID: 463833
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Slide1
Range-wavenumber representation of SAR Signal
santhoshSlide2
SAR Signal (processing)
Two dimensional (energy spread in range and azimuth)
Goal : to focus into single pixel.
Range dimension- spread – duration of chirp transmitted.
Azimuth dimension- spread- duration of synthetic aperture Slide3
zero-Doppler position
.
Fig.: © DLR
X-axis
distance
Range variation
Range variation causes phase variation in received signal as a function of
azimuth Slide4
Formation of the Azimuth Chirp SignalSlide5
transmit waveform amplitude
antenna gain variation over synthetic aperture
range-dependent phase component
quadratic phase term due to transmitted chirp waveform
Demodulated baseband SAR signal
includes R
-4
and target RCS factorsSlide6
Chirp transmitted
Delayed received signal
Demodulated base band signal
Range Fourier Transform- POSP
Azimuth Fourier Transform – 2d frequency domain – POSP
Approximation (linearization) of phaseRange – Inverse Fourier transform – range – Doppler domain Slide7
RDA
Range FFT on raw data – matched filter(pulse compression)- azimuth FFT –secondary range compression –
Range IFFT (range –Doppler domain) – RCM in Doppler domain by
sinc
interpolation (depends on absolute Doppler)- azimuth compression filter
– azimuth IFFT
2D Fourier Domain (3 targets)
Raw Data (single target)
Range Doppler Domain
(After Secondary Range Compression)Slide8
CSA
Azimuth FFT (range – Doppler domain) – chirp scaling
– range FFT- range compression(+ range/azimuth decoupling) – bulk RCM –
range IFFT (range- Doppler domain) – azimuth compression & phase correction –
azimuth IFFT
Range –Doppler domain
After range IFFT