Instituto Brasileiro de Geografia e Estatística

About the publication - Brazilian Network for Continuous Monitoring of the GNSS Systems

About the RBMC

The use of the GNSS (Global Navigation Satellite System) technology revolutionized the activities of navigation and positioning. The geodetic and topographic works became faster, more precise and more economic. As long as the positioning techniques evolve, a number of applications in real time and post-processed have appeared, improving the role of the RBMC.

The geodetic and topographic applications of the GNSS imply the use of the relative method, i.e., at least one station with known coordinates is also occupied at the same time as the occupation of the desired points. The RBMC stations perform exactly the role of the point with known coordinates belonging to the Brazilian Geodetic System - SGB, freeing the user from immobilizing a receiver in a specific point which, many times, is hardly accessed. In addition, the receivers of the RBMC stations have high performance, providing observations of high quality and reliability.

Characterization

RBMC stations are made of forced centering pins, especially designed, and embedded in stable pillars. Most receivers of the network are able to trace GPS and GLONASS satellites, while some of them trace GPS only. These receivers continually collect and store the observations of the code and phase of the carrier waves transmitted by the satellites of the GPS or GLONASS constellations.

Each station has a geodetic antenna and receiver, Internet connection and continuous supply of electricity, which allows the continuous operation of the station.

The coordinates of the RBMC stations are another key component of the final results of the surveyings referenced to them. In this aspect, the major advantage of the RBMC is that all its stations belong to the SIRGAS (Geocentric Reference System for the Americas) Reference Network, whose final coordinates have nearly  ± 5 mm of precision, being one of the most precise networks in the world. Another important role of the RBMC is that its observations are contributing to the regional densification of the IGS (International GPS Service for Geodynamics) network since 1997, assuring a better precision for the IGS products – such as precise orbits – over the Brazilian territory.

Operation

The operation of the RBMC stations is completely automated. Still in the memory of the receiver, the observations are organized into daily files corresponding to sessions starting at 12:01 am and closing at 12:00 am (universal time), with tracing interval of 15 seconds.

After closing a session, the files and their respective observations are transferred from the receiver to the Control Center of the Brazilian Network of Continuous Monitoring of the GNSS Systems - RBMC – Kátia Duarte Pereira, in the Coordination of Geodesy (Rio de Janeiro - RJ). From this point onwards, new files in the standard RINEX 2 format are created, in which the quality control of the observations is carried out. Then the RINEX 2 data files and the orbits transmitted are compressed and made available in the download area of the IBGE portal.

Occasionally, some loss of data due to problems in the Internet connection and lack of energy can occur and are immediately reported through the RBMC Twitter (https://twitter.com/IBGE_RBMC). As far as possible, the data are recovered as soon as the situation is back to the normal condition. However, some data can be lost due to memory limitation in some receivers. In the face of it, we recommend to check with the supplied channels the condition of the station that will be used before carrying out any surveying.

Note: we ask RBMC users to cite that the data were provided by the IBGE, sponsor of the RBMC project, in their works. We also ask RBMC users to not pass the data on, yet guide other users to download them on the IBGE page (RBMC) or request them directly to the IBGE through email ibge@ibge.gov.br.