GNGTS 2017 - 36° Convegno Nazionale

GNGTS 2017 S essione 1.2 181 from a virtual reference station (i.e. a VRS services) placed less than 2 km away (O’Keefe, 2016). Corrections are applied to the GNSS data coming from satellites and tracked by the Rover, in this way a centimeter precision is still reachable even for single-frequency device. CRS is currently developing and testing its proprietary cost-effective GNSS device called LZER0 for both post-processing and real-time applications. LZER0 is based on the well-known raspberry pi platform. The model we adopted is the PI ZEROW (https://www.raspberrypi.org/ ) with low power consumption but equipped with Wi-Fi and Bluetooth features. We decided to use this platform because of its wide range of applications and the huge user community. Raspberry is plugged to a U-BLOX GNSS single-frequency receiver (https://www.u-blox. com/en) with a Tallysman GNSS antenna (http://www.tallysman.com/ ). A circuit board has been developed by the CRS staff to connect raspberry to the U-BLOX receiver; furthermore the board implements a charging system for the internal LiPo battery (2000mAh) and a safe shutdown procedure (based on a PIC microcontroller http://www.microchip.com) . The O.S. is a Linux Debian for raspberry called Raspbian Jessie and a 3D printed box has been project to include all the circuitry. The GNSS elaboration running on the raspberry is performed with two packages: • RTKLIB 2.4.3; • BKG Ntrip Client (BNC). Fig. 1 - The Cazzaso landslide near Tolmezzo is mapped on the top right. 6 GNSS single-frequency devices (DEDALOS system, GPS1, GPS2, GPS3, GPS4, GPS5 and GPS6) and 1 GNSS dual-frequency device (CASO) are monitoring the phenomenon (top center map), the blue arrows show the horizontal velocities (combination of NS and EW components) and the red ones show the vertical velocities. On the bottom right the numerical annual velocities for each site. ON the left side two different plots about the same site (GPS3). They both include a huge landslide slip in the EW component caused by rainfalls. That information has been used by the municipality and by the Regional Civil Protection to alert the Cazzaso citizens and to temporarily close the access route to the village just under the landslide.