Accurate Doppler Parameters Estimation of Geo-SAR Based on Elliptical Orbit

In this paper, three aspects which are the orbital eccentricity, the ellipsoidal earth model and the Earths self-rotation are considered to calculate the accurate values of Doppler centroid and Doppler FM rate of spaceborne SAR. Since the 2-D attitude steering is necessary for Geo-SAR, this paper analyzes the Doppler parameters with and without the attitude steering respectively next. The conclusions are proved as the effective approach with high practicality for the Doppler parameter estimation of Geo-SAR. The analytical expressions of Doppler can be used for the spaceborne SAR at any orbital altitude with any space resolution, and the accuracy is high. Based on the conclusion, the Doppler centroid and Doppler FM rate properties of Geo-SAR moving in elliptical orbit are analyzed.