InSAR datum connection using GNSS-augmented radar transponders

Deformation estimates from interferometric synthetic aperture radar (insar) are relative: they form a ‘free’ network referred to an arbitrary datum, e.g. by assuming a reference point in the image to be stable. however, some applications require ‘absolute’ insar estimates, i.e. expressed in a well-defined terrestrial reference frame, e.g. to compare insar results with those of other techniques. we propose a methodology based on collocated insar and global navigation satellite system (gnss) measurements, achieved by rigidly attaching phase-stable millimetre-precision compact active radar transponders to gnss antennas. we demonstrate this concept through a simulated example and practical case studies in the netherlands.