Prediction of SAR focus performance using ephemeris covariance

Synthetic-aperture radar (SAR) focus can be achieved based on either accurate ephemeris data or SAR processing parameters obtained from an autofocus process. For an SAR mapping project, a decision to choose one approach must be made in the early phase of system design. This requires a detailed analysis to predict the focus performance based on the predicted performance of the ephemeris data. For the Magellan project, this analysis is complicated by the facts that the Magellan radar is operated in a burst mode, and the Magellan radar maps the surface of Venus from a highly elliptical orbit. An analysis that is general enough so that both the strip mapping mode SAR system and the burst mode SAR system are considered is presented. The final result indicates that the ephemeris data obtained from the Magellan navigation system provides sufficient accuracy for meeting the Magellan image resolution requirement