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Geodesy

Geodesy is concerned with the representation, dimension and positioning of the Earth in space, and the temporal variations, including its gravity field.

Introduction

The expansion of Global Navigation Satellite Systems (GNSS, including GPS) is changing the classical geodetic approach based on two reference models - the horizontal component (Geodetic Network) and the vertical component (Levelling Network) which were independently established - by replacing it with a single three-dimensional reference model where all coordinates are obtained in the same way. GPS height (above WGS84 ellipsoid) can be associated with orthometric height (above mean sea level and measured along the plumb line) without losing excessive accuracy, while incorporating an additional geodesic component: gravity.

Maintaining stable references in a Geodetic Infrastructure requires incorporating the time variable due to, among other things, the movement of the Earth's continental plates (Europe is separating from North America at a rate of 3 cm per year). The objective of the project, which started in 2002, is to improve the accuracy and density, and further develop a four-dimensional Geodetic Infrastructure in Gipuzkoa, taken to be a local densification of the current European (ETRS89) and global (ITRF2005) Geodetic Reference Frames.

Administrations or individuals that wish to share their data/experience are welcomed as Gipuzkoa's Geodetic Infrastructure has a user-oriented approach.

Our objectives

  • Offer a Geodetic Infrastructure in permanent updating that serves as a reference to the different geodetic and topographic works that are carried out in our territory of Gipuzkoa. All this through a GNSS Stations Network , a Geodetic Signals Network  and some recommendations for links to that infrastructure.
  • Increase the precision, densify and maintain a four-dimensional Geodetic Infrastructure, understood as a local densification of the current State Geodetic Reference Systems (RedNAP08) , european (ETRS89 and EVRS) and global (ITRF2014).

Gipuzkoa GNSS network

Features

Network of GNSS Reference stations

This network includes stations, both public and private, of our vicinity. In this way the user accesses an infrastructure of higher density, and has several connection options, as our own data are exchanged with new networks as Bizkaia, Euskadi, Teria and RedGAE.

The network is set up with distances less than 20 km from any point in Gipuzkoa which means that centimetric accuracy can be achieved in real time in geodesic and topographic studies.

Since 2005, the Network processes weekly solutions, monitors the received observations and the generation of real-time corrections.

Each GNSS Reference Station stores RINEX data for post-processing and generates simple base corrections (RTK) : CMR +, RTCM 3.0 RTCM2.3  via NTRIP protocol, together with network corrections (NRTK): iMAX, MAX, and VRS. To obtain information about the stations, click on their location. Users can also download RINEX data from the BIDA station of the Bidasoa Institute in Irun.

Source: Public GNSS Networks in Spain and Portugal

History

  • 1997
    Gipuzkoa installs its first Continuous GPS Station, called GFA, on the roof of its headquarters.
  • 2005
    In this urban environment, the GFA station was losing satellite visibility and, as a result, it was replaced by a network of three GPS stations: ELGE, LAZK and IGEL, in conjunction with the Municipality Councils of Elgeta and Lazkao, and the Igeldo Meteorological Observatory.
  • 2007
    The network is updated to also manage GLONASS signals as well as GPS, and a new station, PASA, is incorporated in the AZTI facilities in Pasaia.
  • 2015
    The PASA station joins the EPN network (EUREF Permanent GNSS Network) that defines the Geodetic Reference Frame in Europe. It is the only EPN station in the area; the nearest EPN stations are in Ciboure, Logroño and Santander.
  • 2016
    The four stations in the network are upgraded to receive Galileo and BeiDou signals.
  • 2017
    The network integrated in 2015 in EPN Densification begins to obtain combined solutions from 3 Analysis Centers.
  • 2019
    The network is incorporated into the EPOS (European Plate Observing System) infrastructure.
  • 2021
    Since mid 2008, users have connected to the network 266,153 times. The Gipuzkoa GNSS Network handles an average of 81.2 connections of 45.6 minutes duration per working day.

Documentation