Abstract
Motion error is one of the most serious problems in airborne synthetic aperture radar (SAR) data processing. For a smoothly distributing backscatter scene or a seriously speed-varying velocity platform, the autofocusing performances of conventional algorithms, e.g., map-drift (MD) or phase gradient autofocus (PGA) are limited by their estimators. In this paper, combining the trajectories measured by global position system (GPS) and inertial navigation system (INS), we propose a novel error compensation method for varying accelerated airborne SAR based on the best linear unbiased estimation (BLUE). The proposed compensating method is particularly intended for varying acceleration SAR or homogeneous backscatter scenes, the processing procedures and computational cost of which are much simpler and lower than those of MD and PGA algorithms.
Highlights
Space-borne and airborne synthetic aperture radar (SAR) can work well day-and-night and weather-independently [1,2,3]
With high resolution image production, SAR is widely applied in remote sensing applications, e.g., Earth observation, marine surveillance, earthquake and volcano detection, interferometry, and differential interferometry
Achieving a high-quality SAR image from the systems with platform trajectory error has been a hot topic in airborne SAR configurations
Summary
Space-borne and airborne synthetic aperture radar (SAR) can work well day-and-night and weather-independently [1,2,3]. On the premise of obtaining the trajectory of the antenna phase center (APC), the back projection (BP) algorithm is the most precise imaging method It has the largest computational cost, and most Fast Fourier Transform (FFT)-based focusing methods, which can obviously reduce computational cost, are based on uniform sampling in the range and azimuth dimensions, while in airborne SAR missions, motion error will cause the APC deviation from the ideal position, and essentially leads to non-uniform spatial sampling. In strip-map or sliding spotlight SAR processing, the echo data needs to be divided into sub-apertures to apply PGA algorithms to correct motion error, which will lead to phase discontinuities along the azimuth direction. This restricts the phase-depending applications, e.g., interferometry and differential interferometry.
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