INGV (National Institute of Geophysics and Volcanology, Italy) is one of the institutions that studies and monitors the geophysical phenomena (earthquakes, volcanic eruptions, landslides, etc.) that occur on Earth. During these events, it is essential to carry out a large, detailed and fast map of the affected areas. If we think of the difficulties encountered during the mapping of the fault sources for the 2016 earthquake in central Italy, we can understand how the UAS (Unmanned Aircraft System) can be a valid "low-cost" alternative to the traditional methods of surveys. These devices, thanks to precision instrumentation such as GNSS (Global Navigation Satellite Systems) receivers and IMU (Inertial Measurement Unit) control units, allow a detailed reconstruction of the investigated areas, especially for small-scale analysis applications. These aircraft are based on multiple technologies and show great investigative capabilities, therefore they must be considered as complete systems. Starting from these concepts, we have developed a low-cost RTK/PPK (Real Time Kinematic/Post Processing Kinematic) GNSS survey system on "commercial" UAVs (Unmanned Aerial Vehicles), i.e. professional drones that are not created to be modified. We have demonstrated how the integration of a GNSS RTK/PPK module on commercial UAVs makes the system efficient for the reconstruction of a highly detailed and precise DEM (Digital Elevation Model), without using GCP (Ground Control Point), allowing to make precision measurements in areas that are difficult to explore and investigate. Indeed, the altimetric trends of the PPK processing without GCPs are perfectly comparable with those of the PVs (Verification Points) deriving from RTK analysis and sshow small acceptable deviations. The height differences between PVs measurements and those deriving from the DEM in the same planar coordinates vary between a minimum of 1 cm and a maximum of 7.8 cm. Based on these results, we can state that the precision mapping with a drone equipped with an on-board GNSS module does not differ much from the technique that involves measuring GCP on the ground, in reality, it is comparable in terms of errors, even on the more difficult field of altitudes.

<p>In the last 15 years, INGV has built an important geodetic research infrastructure (RING - Rete Integrata Nazionale GNSS) consisting of a distributed network over the national territory of more than 200 GNSS sensors. Data are recorded in real and quasi real-time in various INGV centre of acquisition, with the aim to provide geodetic products useful to the scientific community. Presently, RING provides daily GPS 30 seconds files distributed in Rinex format. Here we introduce a prototype service for broadcasts real-time streaming GNSS/GPS data from a subset of the RING stations. We will show two use cases of the services that are streaming for raw data exchange for the estimation of the Total Electron Content (TEC), and streaming of GNSS corrections for positioning in NRTK (Network Real Time Kinematic). GNSS signals at different frequencies can be used for the estimation of the Total Electron Content (TEC) due to the dispersive characteristics of the ionosphere. Real-time kinematic (RTK) positioning, instead, has been effectively used, and we will show some examples, for various research campaigns such as the precision positioning of seismic arrays, the real-time positioning of Unmanned Aerial Vehicles (UAV) used for topographic mapping, and landslide monitoring.</p>