Error analysis of pixel positioning accuracy of SAR images based on R-D location model

The range-doppler (R-D) model, which requires no reference points and is independent of satellite attitude knowledge and control, is used to determine the location of SAR image. However, the error of R-D model has not been analyzed. This paper investigates the effects of the pixel positioning accuracy of SAR images on uncertain measurement errors such as range measurement, Doppler center frequency measurement, orbit and the earth mode. The results indicate the earth model and zero-doppler condition have especially severe effect on the pixel positioning accuracy. But the exact earth model and Doppler center frequency true-value have been used, orbit errors become the critical errors. The atmospheric delay error is less than the other errors, however, this delay error is remarkable in low latitude areas. Moreover, the pixel positioning errors of SAR images are nonlinear, and the errors decrease gradually with decreasing latitude as well as increasing longitude.