GPRI: Gamma Portable Radar Interferometer

The GAMMA Portable Radar Interferometer (GPRI) is a ground-based real-aperture radar system with rotating antennas operating at Ku-band with 17.2 GHz.

The GPRI is ideally suited for millimeter-precision deformation measurements, long-term monitoring, and digital elevation model (DEM) generation. The system can be rapidly deployed (30 - 45 minutes until the first acquisition) and provides very high temporal resolution. Repeat rates intervals of 60 seconds are possible for full 360° scans. Smaller sectors can be scanned within a few tens of seconds. Along track interferometry permits temporal baselines of a few milliseconds.

The high signal quality of the GPRI within up to 10 km radius is ensured by the high gain of the narrow-beam (0.39°) real-aperture antennas. The real aperture antennas ensure coherent imaging of quickly decorrelating targets like vegetation or water. The two receive antennas, separated by a vertical baseline, support topographic and volume measurements.

The standard GPRI with 3 antennas supports interferometric repeat-pass and single-pass acquisitions. For advanced studies, GAMMA manufactures polarimetric and polarimetric-interferometric GPRIs with 6 antennas. A bistatic version with two synchronized GPRIs is also available.

The GPRI permits a wide range of interferometric and change detection applications for monitoring of dynamic processes. Observable processes are, e.g., flexure of bridges, vibration of infrastructure, and the motion of water waves, snow avalanches, sea ice, landslides, glacier flow, slope stability assessment, and deformation of infrastructure and surfaces due to underground working or mining. The two receives antennas permit single-pass interferometric DEM generation and volume change measurements on natural mass movements and mining.

At GAMMA we mainly use the GPRI to monitor potentially unstable slopes and rocks, but other applications as glacier velocity mapping and infrastructure applications are also well supported.

First instruments were commercialized in 2010. 

The instrument generates data in the RAW and range-focused SLC format. For  interferometric processing of the GPRI data the GAMMA Software is required.

A list of publications describing specific instrument properties, modes or applications can be found here: Instrument-specific Publications.

A full list of available applications where the GPRI was used or mentioned can be found here: Instrument Application Publications.