Abstract: To further improve DEM precision for InSAR system,4 factors affecting phase precision are analyzed for the non-linear ECS auto-registration imaging algorithm.The results are given as follows.The equivalent error of relevant velocity between radar and scatter is very small and can be ignored.When the system resolution is better than 0.1 m,quadratic approximation error in the non-linear ECS auto-registration generates 0.1 pixel registration error,and it cannot be ignored.The second-order Taylor approximation error in the non-linear scaling is very small and can be neglected.During interferometric motion compensation,the flat assumption error in the imaging causes locus error and phase error,which cause some impact and should be considered for high-precision InSAR system (DEM precision is higher than 0.5 m).The above error analyes will provide some guidance for further improving phase maintenance precision and DEM precision.

Key words: non-linear, extended chirp scaling(ECS), auto registration, interferometric synthetic aperture radar(InSAR), interferometric phase, digital elevation model(DEM)