BD992 satellite-navigation receiver

The Trimble BD992 is a dual-antenna, multi-frequency GNSS receiver board from Trimble that provides centimetre-level position and precise heading from a single OEM module. It is a satellite-navigation receiver for embedded use, built on Trimble Maxwell 7 technology with two 336-channel chips, one for each antenna, and it can be fitted with the Trimble ProPoint positioning engine.

The module tracks GPS (L1 C/A, L2E, L2C, L5), GLONASS (L1 C/A, L2 C/A, L3 CDMA), BeiDou (B1, B2, B3), Galileo (E1, E5A, E5B, E5AltBOC, E6), IRNSS (L5), QZSS and SBAS, and it has an MSS L-band channel for OmniSTAR and Trimble RTX corrections. With corrections the unit can give centimetre-level positions without a base station. The positioning accuracy with RTK is 0.008 m horizontal and 0.015 m vertical, and with DGNSS it is 0.25 m horizontal and 0.50 m vertical. Heading on a 2 m baseline is better than 0.09 degrees. The maximum position and attitude update rate is 50 Hz and the position latency is below 20 ms. RTK initialization typically takes under 8 seconds with a reliability above 99.9%.

The datasheet explains that a single antenna has difficulty finding its position relative to the vehicle when the dynamics are low, and heading from two antennas removes that problem. The moving-baseline RTK function is intended for precision landing on moving platforms. Different software configurations are available, from L1 DGPS up to a four-constellation, triple-frequency RTK unit, and features are upgraded by password.

For integration, the board measures 100 mm x 60 mm x 11.6 mm and weighs 60 grams. It needs 3.3 VDC and typically draws 2.3 W. It connects through a 44-pin header, and the two antennas use MMCX connectors; the antenna LNA supply accepts 3.3 to 5 VDC at up to 400 mA. Interfaces are Ethernet, USB 2.0, three RS-232 ports and one CAN port, and output protocols include NMEA-0183, Trimble GSOF and NMEA 2000, with CMR, sCMRx and RTCM inputs. The operating temperature is -40 °C to +75 °C, with tailored MIL-STD-810 vibration and shock tests. It limits velocity to 515 m/s and altitude to 18,000 m.

Typical applications are heading and positioning for unmanned aircraft and other vehicles, precision landing on moving platforms, survey and machine guidance, and any embedded system that needs an RTK position with dual-antenna heading.