Instituto Brasileiro de Geografia e Estatística

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Geodesy

RBMC -Brazilian Network for Continuous Monitoring of the GNSS Systems

About RBMC

The use of the GNSS technology (Global Navigation Satellite System) sparked a complete revolution in navigation and positioning. The geodetic and topographic works are now carried out in a faster, more precise and economic way. As positioning techniques improve, several real-time and post-processing applications have been brought forward, making RBMC’s role even broader.

In the GPS geodetic and topographic applications, the use of the relative method is implicit. This means that at least one station of known coordinates is also occupied simultaneously to the occupation of the points of interest. The RBMC acts as known coordinates belonging to the Brazilian Geodetic System (SGB), preventing the user from the risk of placing a fixed receiver at, sometimes, dangerous or difficult areas to reach. Besides, RBMC stations are equipped with high-performance receivers, providing observations of great quality and reliability.

Characterization

The RBMC stations are made of forced centering pins, specially designed, and threadened on stable pillars. Most of the network receivers can track GPS and GLONASS satellites, whereas some of them can only trace GPS. These receivers constinuously collect and store the code and phase observations of the carrier waves transmitted by satellites of the GPS or GLONASS constellations.

Each station has a receiver and a geodetic antenna, Internet connection and constant power supply which enables the continuous operation of the station.

The coordinates of the RBMC stations are another very important aspect to the production of the final results of the surveys referenced to them. Moreover, the major advantage of the RBMC is that all of its sations integrate the Reference Network SIRGAS (Geocentric Reference System for the Americas), whose final coordinates are ± 5 mm-precise, making it one of the most accurate networks in the world. Another relevant role of RBMC is that its observations have been contributing, since 1997, to the regional densification of the IGS network (International GPS Service for Geodynamics), assuring, thus, a better precision of the IGS products – such as precise orbits – on the Brazilian territory.

Operation

The operation of the RBMC stations is thoroughly automated. The observations are organized, stil in the receiver’s memory, in daily files, corresponding to sessions starting at 00h 01min and ending at 24h 00mim (Universal Time), with track intervals of 15 sec.

After the end of a session, the files with the respective observations are tranfered from the receiver to the Control Center of the Brazilian Network System of Continuous Monitoring of the GNSS Systems – RBMC - Kátia Duarte Pereira, in the Department of Geodesy (Rio de Janeiro-RJ). At this point, new files of the standard format RINEX2 are created, with observation quality control. Then, data files RINEX2 and the orbits are transmitted and made available in the download area in the IBGE portal.

Occasionally, some data losses due to Internet connection problems and lack of electricity may occur. But they are immediatelly reported through the RBMC Twitter (https://twitter.com/IBGE_RBMC) and in the information pagehttps://www.ibge.gov.br/home/geociencias/geodesia/rbmc/rbmc_inf.php. Data are recovered as soon as the situation is back to normal. However, due to the memory limitation of the receivers, some data can be lost. Therefore, it is recommended that the situation of the station be verified before the available channels are used.

Observation: IBGE (maintainer of the RBMC project) should be referenced as the source of the studies produced by RBMC users. Data should not be forwarded, but rather directly downloaded from the IBGE website or required through email ibge@ibge.gov.br.

 

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