DOI: 10.5880/fidgeo.2024.004
title: Multi-frequency, multi-constellation, GNSS observations at low-cost tectonic GNSS stations in Greece

description: The TectoVision GNSS network in Greece was set up using European Research Council funding in partnership between German and Greek institutions. The project aims to deepen our understanding of suspected microplate motions in Greece. A total of 72 GNSS stations are planned for the TectoVision network. 
 Two types of GNSS station equipment is used, reflected by the 4 character station ID. Stations with ID beginning with 'TT' were installed using the tinyBlack receiver. The stations with ID beginning 'TM' were set up using the Minimum Cost GNSS System (MCGS) design. RINEX (v3.05 as of May 2024) data at 30 seconds sampling interval are provided. Most of the data are sent over mobile internet via routers that are connected to the receivers via LAN cable. If required, the RINEX files can be converted to other versions using the GFZ software GFZRNX (Nischan, 2016). Raw observation data can be made available upon specific request. 
 
 
Hardware: 
The GFZ developed tinyBlack receiver combines cost efficient L2C GNSS receivers (here Swiftnav Piksi) with PC-based data logger package, internal storage, and interfaces. The control software is designed for remote operation ensuring long-term continuous tracking. The tinyBlack receivers provided by the GFZ spin-off maRam UG (Germany) are installed in combination with Harxon GPS500 survey antennas. The tinyBlack stations provide GPS (L1/L2), GLONASS (G1/G2), and Galileo (E1/E5b) data. 
 
The low-cost MCGS stations are coming in 2 versions from a GNSS technology transfer project at GFZ. Both versions operate a ublox F9P receiver and an integrated chip-antenna with a pyramidal antenna radome. One version provides GPS (L1/L2), Glonass (G1/G2), Galileo (E1/E5b) and also Beidou (B1/B2) data. The other version (currently only 3 systems installed) is designed for low power operation in remote areas with data telemetry over a narrrow bandwidth radio link. This version delivers only GPS (L1/L2) data without doppler observations at a reduced data rate of 60 seconds. 
 
 
Monumentation: 
There is a variety of monumentation for these stations, with the design of the monumentation being low-cost. Most are connected to a thread that is attached to a stainless steel pin which is glued into masonry or bedrock. Most sites are installed on rooftops of public buildings. The MCGS is sometimes clamped to an existing sturdy pole connected to the roof of the building. Some stations are connected to an extending stainless-steel arm that we have drilled into the side of a building. Photos of the station are provided with the standard GNSS station log-files (as metadata). If the instrumentation at existing monuments is later changed to other hardware types, the station ID retain the original TT and TM 4-character IDs. 
 
 
Metadata: 
Station-specific metadata records are stored in IGS sitelog files available via ftp.
description: Most of our stations are sending data to the GFZ server every hour. Most of the data are sent over mobile internet via routers that are connected to the receivers via LAN cable. Installation was made in multiple phases therefore not all stations begin their measurements on the same day (earliest measurement beginning on May 12th 2023).
description: IGS formats and standards. RINEX 3.05 (latest version). https://igs.org/formats-and-standards/
description: List of GNSS stations with links to data and metadata. Note, we only provide metadata files for a station once the quality control checks are complete (which can take some months to complete after the installation of a new station).