Method of determining the direction of velocity space-variance in GEO SAR

Geosynchronous Earth Orbit Synthetic Aperture Radar (GEO SAR) has the advantages of short repeat time, large coverage area and so on. For the long aperture time and high orbit height, the effect of velocity space-variance on GEO SAR is more severe than on Low Earth Orbit SAR (LEO SAR). However, the spatial variation of velocity is different in different directions, which will bring new challenge to the imaging process. This paper analyses the effect of velocity space-variance on GEO SAR and LEO SAR respectively, proposes a method to find the direction of velocity spacevariance. Finally, the correctness of this method is proved through imaging simulation. (4 pages)