High-Temporal-Resolution GNSS-R InSAR Elevation Deformation Monitoring Using Range-Compressed Phase

Abstract

Existing GNSS-reflectometry interferometric synthetic aperture radar (GNSS-R InSAR) elevation deformation monitoring methods derive interferometric phases from SAR images, causing measurement intervals to be constrained by the synthetic aperture duration and limiting their ability to capture rapid deformation. To overcome this limitation, this letter proposes a high-temporal-resolution GNSS-R InSAR method using range-compressed phases. Once the target location has been determined through initial SAR imaging, the proposed method directly extracts range-compressed phases from each azimuth sample for elevation deformation retrieval without repeated SAR imaging. The projection stability and phase-noise characteristics associated with range-compressed phase extraction are analyzed, and corresponding filtering strategies are employed for noise suppression. Experiments at a 0.4s validation interval demonstrate that, after filtering, subcentimeter elevation deformation retrieval accuracy can be achieved, with correlation coefficients (CCs) exceeding 0.97 under different satellite observation geometries. Compared with conventional GNSS-R InSAR approaches, the proposed method significantly improves temporal resolution, with a theoretically achievable native phase-update interval of approximately 1 ms.