GNSS Surveying in Brazil: RBMC CORS, SIRGAS2000 & RTK Guide
RTK GNSS survey in Brazil uses the SIRGAS2000 coordinate system (based on ITRF2000, epoch 2000.4) and the RBMC CORS network (Rede Brasileira de Monitoramento Contínuo dos Sistemas GNSS) operated by IBGE for NTRIP corrections. RBMC coverage is good in the south and southeast but thins significantly across the Amazon basin, Cerrado, and remote northern and western states. For sites beyond reliable RBMC coverage, deploy a local base+rover configuration: any AP10 or AP20 as a lightweight base on a known control point, or a MAX5 dedicated base station with 5W LoRa and 25 km range. No internet required. All APEKS receivers use international firmware with no geo-fence restrictions — OTA updates work identically in Brazil as in any other country.
- Brazil GNSS Survey Overview
- SIRGAS2000 — The Brazilian Coordinate System
- RBMC CORS Network — Coverage and Limitations
- Connecting to RBMC via NTRIP
- When RBMC Is Not Available — Base+Rover Approach
- The Core Challenges in Brazil GNSS Survey
- Recommended Equipment for Brazil
- Field Deployment Scenarios
- FAQ
Brazil GNSS Survey Overview
Brazil operates SIRGAS2000 (Sistema de Referência Geocêntrico para as Américas 2000) as its national geodetic datum, maintained by IBGE (Instituto Brasileiro de Geografia e Estatística). The RBMC (Rede Brasileira de Monitoramento Contínuo dos Sistemas GNSS) provides NTRIP-based RTK corrections across covered areas. Brazil is Latin America's largest survey market — and one of the most technically demanding. Infrastructure projects span every terrain type: dense urban construction in São Paulo and Rio de Janeiro, agricultural demarcation across millions of hectares of Cerrado and soy belt, hydroelectric and transmission line surveys through Amazonian rainforest, and oil and gas infrastructure across coastal and interior zones.
KEY FACTS FOR FIELD SURVEYORS:
- National coordinate system: SIRGAS2000
- Reference frame: ITRF2000, epoch 2000.4
- Ellipsoid: GRS80
- Projection: UTM (Universal Transverse Mercator)
- Brazil spans UTM Zones 18S to 25S
- São Paulo / Rio: UTM Zone 23S
- Brasília / Goiás: UTM Zone 22S or 23S
- Manaus / Amazon: UTM Zone 20S or 21S
- Geoid model: MAPGEO2015 (IBGE geoid for Brazil)
- NTRIP protocol: v1 and v2 supported by all modern RTK receivers
- RBMC operator: IBGE (ibge.gov.br)
SIRGAS2000 — The Brazilian Coordinate System
SIRGAS2000 replaced SAD69 (South American Datum 1969) as Brazil's official geodetic reference system. Modern cadastral, infrastructure, and construction projects require SIRGAS2000 coordinates. Legacy surveys based on SAD69 or Córrego Alegre (another legacy datum used in older Brazilian mapping) require datum transformation before comparison with current coordinates. SAD69 and Córrego Alegre carry significant horizontal offsets from SIRGAS2000 — typically 60–70 metres for SAD69 — making this one of the largest datum shifts of any country transitioning to a modern geocentric reference system. Do not compare coordinates across datums without applying the correct transformation parameters.
SIRGAS2000 SETUP IN ApekSurv:
- Select coordinate system: SIRGAS2000 / ITRF2000
- Confirm UTM zone for your project area:
Zone 18S: far western Brazil (Acre, western Amazonas)
Zone 19S: western Amazon (parts of Amazonas, Pará)
Zone 20S: central Amazon (Manaus area)
Zone 21S: central-west (Mato Grosso, western Pará)
Zone 22S: central Brazil (Brasília, Goiás, Mato Grosso do Sul)
Zone 23S: southeast Brazil (São Paulo, Rio de Janeiro, Minas Gerais)
Zone 24S: northeast (Bahia, Espírito Santo)
Zone 25S: far northeast (coastal states) - Load MAPGEO2015 geoid model for correct ellipsoidal to orthometric height conversion
- Verify with a known IBGE control point before commencing field observations
SAD69 AND CÓRREGO ALEGRE TRANSFORMATION: Legacy maps and as-built drawings may use SAD69 or Córrego Alegre. These datums carry a significant horizontal offset from SIRGAS2000 — typically 60–70 metres for SAD69. Do not compare coordinates across datums without applying the correct transformation parameters in ApekSurv. For SAD69 to SIRGAS2000, use the IBGE-published transformation grid and verify on a minimum of two independent control points before commencing production survey.
RBMC CORS Network — Coverage and Limitations
The RBMC (Rede Brasileira de Monitoramento Contínuo) is operated by IBGE and provides free NTRIP access to all registered users. The network supports RTCM 2.x and 3.x correction formats and is accessible via standard NTRIP v1 and v2 protocols. RBMC station density is highest in the south and southeast — São Paulo, Rio de Janeiro, Paraná, Rio Grande do Sul — where station spacing supports reliable RTK at standard baselines. Coverage thins dramatically across the Amazon basin and northern states, where RBMC stations are hundreds of kilometres apart. For survey teams working outside the south and southeast, RBMC baseline distances frequently exceed 100 km, making base+rover deployment the correct approach.
| Region | States | RBMC Coverage | Recommended Approach |
|---|---|---|---|
| South | PR, SC, RS | Good | NTRIP via RBMC |
| Southeast | SP, RJ, MG, ES | Good | NTRIP via RBMC |
| Centre-West | GO, DF, MS, MT | Moderate | NTRIP where available; base+rover for remote |
| Northeast | BA, PE, CE, RN, PB, AL, SE, MA, PI | Limited to sparse | Base+rover recommended |
| North | AM, PA, RO, AC, AP, RR, TO | Sparse to absent | Base+rover with MAX5 required |
| Amazon basin | Remote forest and river corridors | Absent | MAX5 base+rover essential |
| Agricultural frontier | Cerrado and soy belt, remote MT/PA/TO | Sparse | MAX5 base+rover recommended |
Connecting to RBMC via NTRIP
When RBMC Is Not Available — Base+Rover Approach
For project areas beyond reliable RBMC coverage — Amazon corridor surveys, agricultural demarcation in remote Mato Grosso and Pará, transmission line routes through the Cerrado — the base+rover configuration provides full RTK accuracy from a self-contained correction source. Base+rover RTK accuracy is identical to CORS-based RTK when the base is correctly set up on a coordinated IBGE control point. The correction source (RBMC vs local base) does not affect the rover's Fixed accuracy ceiling.
LIGHTWEIGHT BASE (AP10 OR AP20): Deploy any AP10 or AP20 on a known IBGE control point or established project benchmark. Configure as base station in ApekSurv. The receiver broadcasts corrections via built-in 2W UHF radio to the rover within 8–15 km. Suitable for project areas up to 15 km radius from the base. No internet, no SIM, no RBMC subscription required for the correction link.
MAX5 DEDICATED BASE STATION FOR LARGE REMOTE SITES: Deploy the MAX5 on a central control point. 5W LoRa radio broadcasts corrections up to 25 km across open terrain — covering large agricultural parcels, pipeline corridors, and transmission line routes from a single base position. 13,200 mAh internal battery provides 8+ hours of continuous broadcast without external power. In Amazon and rainforest terrain, radio range will be reduced by vegetation; plan base positions at 15–18 km intervals for forested corridors. Multiple rover teams receive corrections from the same MAX5 simultaneously — suited for multi-team agricultural demarcation across large properties.
The Core Challenges in Brazil GNSS Survey
Symptom: The survey team is working on a transmission line route through Pará, an agricultural demarcation in remote Mato Grosso, or a road construction project in Tocantins. NTRIP connects but shows Float solution only. The nearest RBMC station is 150–250 km away. The team spends the morning troubleshooting a CORS connection that will never deliver Fixed at this baseline distance.
Cause: RBMC station density in the Amazon basin and Cerrado frontier is designed for national geodetic monitoring, not dense survey-grade RTK coverage. Station spacing of 200–400 km in northern and western Brazil means CORS-based RTK is simply not viable for most remote project locations.
Fix: Deploy MAX5 base station on the nearest IBGE SAT control monument or established project benchmark. 5W LoRa covers 25 km across open Cerrado and agricultural terrain. For Amazon forest corridors, plan base positions at 15–18 km intervals accounting for vegetation signal attenuation. Full Fixed RTK for all rovers within range with no CORS dependency.
Symptom: The project enters Amazonian forest or Atlantic Forest coastal zones. Satellite count drops under canopy. Fixed solution drops to Float. The rover cycles between Fixed and Float throughout the session, requiring the operator to wait for re-initialisation after each signal interruption. Survey productivity drops significantly compared to open terrain.
Cause: Dense equatorial rainforest canopy attenuates GNSS signals across multiple constellations simultaneously. Receivers tracking fewer constellations or with fewer channels lose Fixed solution faster and take longer to re-initialise under heavy canopy.
Fix: APEKS receivers track 1408 channels across 7 constellations — GPS, GLONASS, BeiDou, Galileo, QZSS, NavIC, SBAS. Full-constellation tracking maximises the usable satellite pool under canopy, extending Fixed into light-to-moderate forest. For dense canopy where GNSS is denied entirely, plan observations from clearings, forest edges, or elevated positions. Re-initialisation after canopy transit takes 5–15 seconds on a 1408-channel receiver.
Symptom: The project boundary coordinates are provided in SAD69. The new infrastructure design is in SIRGAS2000. The survey team sets up in SIRGAS2000, occupies a boundary monument, and finds a 60–70 metre discrepancy. The team assumes GPS error and spends time troubleshooting equipment that is working correctly.
Cause: SAD69 and SIRGAS2000 carry a horizontal offset of approximately 60–70 metres across Brazil — one of the largest datum shifts of any country transitioning to a modern geocentric reference system. Córrego Alegre, used in pre-1970s Brazilian cadastral mapping, carries a different shift. Any coordinate comparison without the correct datum transformation will show this offset.
Fix: Before field work, confirm which datum all boundary, control, and as-built coordinates are published in. Load the correct datum transformation parameters into ApekSurv. For SAD69 to SIRGAS2000, use the IBGE-published transformation grid. Verify on a minimum of two independent control points before commencing production survey.
Recommended Equipment for Brazil
Equipment selection for Brazil survey must account for the country's extreme terrain and coverage diversity — from reliable RBMC in São Paulo to complete CORS absence in the Amazon. The following configuration covers the full range of Brazilian survey environments.
| Instrument | Role | Key Spec | Brazil Application |
|---|---|---|---|
| AP20 | Standard rover or lightweight base | 1408ch, 120° IMU, 2W UHF, IP67/IK08 | Urban and semi-urban survey where RBMC available; lightweight base for Cerrado and agricultural sites |
| AP20 AR | AR stakeout rover | 1408ch, 120° IMU, bottom 5MP camera, IP67/IK08 | Construction stakeout in São Paulo, Rio, and major city infrastructure; AR overlay for dense layout grids |
| AP40 Laser+ | Laser offset + AR stakeout | 1408ch, 120m laser, IP67/IK08 | Transmission line corridor survey; features across rivers, drainage channels; inaccessible boundary monuments in agricultural zones |
| AP80 Pro | ALL IN ONE flagship | 1408ch, 120m laser, visual measurement, AR, IP67/IK08 | Complex infrastructure; combined laser and visual measurement on the same session |
| MAX5 | Long-range base station | 5W LoRa, 25km, 13200mAh, OLED, IP67/IK08 | Amazon, Cerrado, and Pantanal remote sites; agricultural demarcation; transmission line routes beyond RBMC coverage |
| APS1 | Lightweight handheld RTK | 1408ch, 60° IMU, 210g, IP67 | Agricultural boundary demarcation support; GIS data collection; utility asset mapping |
All APEKS receivers carry international firmware with no geo-fence restrictions. OTA firmware updates work from any internet connection in Brazil — no VPN, no Chinese server dependency. SIRGAS2000 and SAD69 coordinate systems are configurable in ApekSurv.
Field Deployment Scenarios
SCENARIO 1 — SÃO PAULO URBAN CONSTRUCTION (RBMC AVAILABLE): AP20 AR rover connected to RBMC via built-in 4G. Configure SIRGAS2000 UTM Zone 23S in ApekSurv. Load MAPGEO2015 geoid. Verify on IBGE SAT control before commencing. AR stakeout for column grid layout and road alignment. 120° IMU for tilt-compensated recording on urban construction sites. As-staked QA report exported from ApekSurv at session end.
SCENARIO 2 — MATO GROSSO AGRICULTURAL DEMARCATION (NO RBMC): MAX5 base station on established IBGE control monument at property entrance. 5W LoRa covers 25 km across flat Cerrado terrain — sufficient for most large agricultural properties from a single base position. Two AP20 rover teams work the property boundaries simultaneously, both receiving corrections from the same MAX5. Full Fixed RTK throughout. 8+ hour battery covers the full field day. No cellular data required.
SCENARIO 3 — AMAZON TRANSMISSION LINE ROUTE SURVEY: MAX5 base leap-frogged along the corridor, positioned at cleared tower positions or access road junctions every 15–18 km (accounting for forest signal reduction). AP40 Laser+ rover measures tower base positions, river crossing features, and boundary offsets by laser where direct pole access is obstructed by vegetation or water. Single operator covers GNSS and laser measurement in one session.
FAQ
What coordinate system does Brazil use for survey?
Brazil's official coordinate system is SIRGAS2000 (Sistema de Referência Geocêntrico para as Américas 2000), maintained by IBGE. It is based on ITRF2000 at epoch 2000.4 using the GRS80 ellipsoid. Projection is UTM — the specific zone depends on longitude, with Zone 23S covering São Paulo and Rio de Janeiro, Zone 22S or 23S covering Brasília, and Zone 20S covering Manaus. Apply the MAPGEO2015 geoid model for orthometric heights. Legacy surveys may use SAD69 or Córrego Alegre, which carry significant horizontal offsets from SIRGAS2000 and require datum transformation before comparison.
How do I connect to RBMC CORS in Brazil?
Register for free at the IBGE portal (ibge.gov.br) to obtain NTRIP credentials. Configure the caster address, port, and mountpoint in ApekSurv under Communication → NTRIP. Select RTCM 3.x format. RBMC is strongest in the south and southeast. For project areas in the north, centre-west, or Amazon, verify the baseline distance to the nearest RBMC station before relying on NTRIP — distances exceeding 70 km require a local base+rover configuration.
What should I do when RBMC coverage is unavailable?
Deploy a base+rover configuration. Set up an AP10 or AP20 as a base on a known IBGE control point, broadcasting corrections via 2W UHF radio within 8–15 km. For larger areas, use the MAX5: 5W LoRa radio, 25 km range across open terrain, 13,200 mAh battery for 8+ hours. In Amazon forest, plan base positions at 15–18 km intervals to account for signal attenuation through canopy. RTK accuracy is identical to RBMC-based RTK when the base is set up on correctly coordinated control.
How large is the difference between SAD69 and SIRGAS2000 in Brazil?
The horizontal shift between SAD69 and SIRGAS2000 is approximately 60–70 metres across most of Brazil — one of the largest datum transition offsets of any country. Córrego Alegre, used in older Brazilian cadastral mapping, carries a different and variable offset. Never compare SAD69 or Córrego Alegre coordinates directly with SIRGAS2000 without applying the IBGE-published transformation. ApekSurv supports the standard Brazilian datum transformations — load the correct parameters before field work and verify on independent control.
Will Chinese GNSS receivers work in Brazil without firmware restrictions?
APEKS receivers use international firmware with no geo-fence restrictions. OTA firmware updates work from any internet connection in Brazil, including remote areas with satellite or cellular data. Some Chinese GNSS brands ship firmware that requires Chinese server access for updates — verify this explicitly with any non-APEKS supplier before committing to a multi-year Brazilian infrastructure project, as outdated firmware creates RBMC RTCM compatibility issues over time.
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RTK GNSS FOR BRAZIL. RBMC TO AMAZON.
APEKS receivers cover Brazilian survey from São Paulo urban construction on RBMC CORS to Amazon corridor surveys with MAX5 base station at 25 km LoRa range. SIRGAS2000 ready. International firmware. No geo-fence. No CORS dependency for remote sites.
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- IBGE — Instituto Brasileiro de Geografia e Estatística (ibge.gov.br)
- RBMC — Rede Brasileira de Monitoramento Contínuo dos Sistemas GNSS, IBGE 2026
- SIRGAS2000 Technical Specifications — IBGE
- MAPGEO2015 — Brazilian Geoid Model, IBGE 2015
- ISO 17123-8:2015 — Field Procedures for GNSS RTK
- RTCM Standard 10403.3 — Differential GNSS Services
- APEKS MAX5 Base Station Datasheet, 2026
- Unicore Communications UM980 Product Brief