Signal Processing for Digital Beamforming FMCW SAR

Abstract

According to the limitations of single channel Frequency Modulation Continuous Wave (FMCW) Synthetic Aperture Radar (SAR), Digital Beamforming (DBF) technology is introduced to improve system performance. Combined with multiple receive apertures, DBF FMCW SAR can obtain high resolution in low pulse repetition frequency, which can increase the processing gain and decrease the sampling frequency. The received signal model of DBF FMCW SAR is derived. The continuous antenna motion which is the main characteristic of FMCW SAR received signal is taken into account in the whole signal processing. The detailed imaging diagram of DBF FMCW SAR is given. A reference system is also demonstrated in the paper by comparing with a single channel FMCW SAR. The validity of the presented diagram is demonstrated with a point target simulation results.

SAR raw data simulation for multiple‐input multiple‐output video synthetic aperture radar using beat frequency division frequency modulated continuous wave

“…The Doppler shift results from the continuous antenna motion in case of FMCW SAR, which is the main system structure of the MIMO ViSAR considered in this article. After the azimuth Fourier transform of g l , DS ( t r , t a ), the range‐Doppler spectrum, G l , DS ( t r , f a ) is multiplied with the Doppler compensation term as follows: where t r is fast time, f d is the Doppler frequency shift due to the platform motion within the transmission of one sweep, * denotes complex conjugate, and the exponential term represents the Doppler compensation term as described in …”

“…11 The Doppler shift results from the continuous antenna motion in case of FMCW SAR, which is the main system structure of the MIMO ViSAR considered in this article. After the azimuth Fourier transform of g l, DS (t r , t a ), the range-Doppler spectrum, G l, DS (t r , f a ) is multiplied with the Doppler compensation term as follows 18,31 :…”