MicoAir MA-RTK-AIR-982 RTK GNSS with compass - Dual antenna

MicoAir MA-RTK-AIR-982 is the most powerful RTK GNSS module in the MicoAir RTK series, built on the triple-band UM982 receiver with support for L1, L2 and L5. It works as a rover, meaning it receives RTK corrections from a ground base or from the NTRIP network, and achieves horizontal accuracy of 0.8cm + 1ppm and vertical accuracy of 1.5cm + 1ppm. Without corrections, it functions as a standard GNSS module with accuracy around 1.5m. This version is supplied with two antennas, so it can determine heading even without a compass.

Heading determination from two antennas is the main advantage of this module. The receiver compares the phase of the signal arriving at both antennas and calculates the orientation of the machine from their relative position. The result is completely independent of the magnetic field, so the problems that typically affect a drone compass are eliminated, namely interference from power cables, motors, metal parts of the frame, or the surrounding environment. In practice, this means reliable heading near steel structures, high-voltage lines, ships, heavy machinery, or reinforced concrete, where a conventional magnetometer may not always be reliable. In addition, the heading is accurate immediately after power-up, without rotational calibration and without declination.

For best results, both antennas need to be placed as far apart as possible and in the same plane, at least 20 cm apart. The longer the baseline between the antennas, the more accurate the heading. 

Three frequency bands mean more data for ionospheric error calculation and a faster, more stable RTK fix than dual-band modules. The module processes GPS L1C/A, L2P/L2C and L5, BeiDou B1I, B2I and B3I, GLONASS G1 and G2, Galileo E1, E5a and E5b, and QZSS L1, L2 and L5. In RTK mode it tracks over 50 satellites, in standalone mode 28, and provides navigation data at up to 20Hz, which is the highest in the series. The signals GPS L2P and L5, Galileo E5a and QZSS L5 are processed only by the main ANT1 antenna; the second antenna is used for heading determination.

The module also includes a classic IST8310 magnetometer on the I2C bus. GNSS data goes via UART (3.3V LVTTL), the default baud rate is 115200, and the autopilot usually automatically changes it to 230400. The output protocol is NMEA-0183. By default, the module does not send any data; configuration is performed automatically by ArduPilot or PX4 upon connection.

The antennas connect via one SMA connector (ANT1) and two MMCX connectors (ANT1, ANT2). Data pins are on two connectors. The six-pin GH1.25-6P (GND, VCC, RX1, TX1, SCL, SDA) carries the main UART to the autopilot together with the I2C compass, while the four-pin GH1.25-4P (GND, VCC, TX2, RX2) adds a second UART, through which RTK corrections can be fed into the module, for example from a telemetry modem. Status is indicated by three LEDs – Power, PVT (position solution) and RTK (correction status).

The electronics are enclosed in a metal shielded housing with cooling fins that also dissipate heat from the high-performance receiver. Power supply is 4-5V. Dimensions are 39x31,5x16mm and weight is 20g without antennas.

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