GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 1.4 233 THE GEODETIC INTEGRATED MONITORING SYSTEM (GIMS) PROJECT E. Realini, D. Sampietro GReD srl, Como, Italy Introduction. The advent of the Galileo and Sentinel satellites, and their integration with miniaturized in-situ sensors, enables new advanced monitoring solutions which are both cost- effective and highly accurate. Recently, Geomatics Research & Development srl (GReD) experiences showed that an accuracy of few millimeters on daily solutions is reachable using mass-market single-frequency GPS receivers (Caldera et al., 2017). With the advent of Galileo, even better results can be obtained, also because Galileo E5 signals are very promising. Moreover, the availability of the Sentinel 1A and 1B data, which are provided with an open and free access policy, allows the usage of SAR images for ground monitoring purposes at a lower cost compared to few years ago. Finally, the miniaturization of sensors like accelerometers, thermometers, etc. allows for the deployment of a large number of measuring devices provided that their observations, usually highly affected by severe noise, can be properly processed. The observations from these 3 different monitoring techniques, namely EGNSS, SAR and MEMS accelerometers, are complementary in time and space and can be merged to obtain a better understanding of the monitored processes and a more complete knowledge of the deformation phenomenon. In fact MEMS can be used for a real time identification of sudden movements in terms of accelerations, EGNSS receivers allow to identify pointwise shifts at the level of 1 mm per day or 3 mm per 2 hours and SAR images enable the identification of area deformation at level of few millimeters with a latency of few days thus giving a complete picture at all the required spatial and temporal scales. The Geodetic Integrated Monitoring System (GIMS) project, funded the European GNSS Agency under the European Union’s Horizon 2020 research and innovation programme, builds on such a rationale, aiming at developing and commercializing an advanced low-cost system based on EGNSS, Copernicus SAR and in-situ sensors for the purpose of monitoring ground deformations with a focus on landslides and subsidence. In the present work, the main results obtained up to now are described. In the next section, the GIMS hardware is shortly presented, while in the last one the first pilot study to test the system is presented together with some preliminary results. GIMS monitoring station. In this section we provide a brief description of the integrated GIMS monitoring units (the low-cost hardware developed and produced within the project). The unit is basically made by three main components: a GNSS system, a SAR compact active transponder (CAT), and an inertial system including a 3-axis IMU (accelerometer and gyroscope) and a 2-axis inclinometer. GNSS and inertial sub-systems will be included in all GIMS stations. The SAR sub-system is designed as an additional module. Since the CAT is a highly experimental solution, we plan to deploy also a few “standard” passive corner reflectors, that will integrate the CATs and – in case of need – also function as a backup alternative. Given the shape and size of standard a corner reflectors, they will not be attached to GIMS stations, but rather deployed nearby. Starting from the GNSS, GIMS units will employ a u-blox ANN-MB multi-band patch antenna, that will be connected to a u-blox ZED-F9P receiver. The u-blox ZED-F9P receiver module is mounted on an electronic board developed by Saphyrion Sagl. The SAR sub-system will be composed of the prototype CATs designed and produced by Centre Tecnològic de Telecomunicacions de Catalunya (CTTC). From a mechanical standpoint, a CAT is basically a 40cm x 20cm x 10cm weather-proof box, containing the CAT electronic components, that will be attached to the GIMS station vertical pole. The CAT must be inclined to aim towards the SAR satellite. The antenna line-of-sight must not be occluded by other elements, to guarantee satellite visibility. The inertial sub-system will consist of two different kinds of instruments: