Theory and design of interferometric syntheticaperture radars is a good explaination of the principal and basic idea of InSAR-Interferometric synthetic aperture radar (InSAR) is a method which may provide a means

of estimating global topography with high spatial resolution and height accuracy. The paper pre-sents a derivation of the signal statistics, an optimal estimator of the interferometric phase,and the expressions necessary to calculate the height-error budget. These expressions are used to derive methods of optimising the InSAR-system　　　

parameters, and are then used in a specific design example for a system to perform high-resolution global topographic mapping mission.