Unicore Communications UM980

The UM980 from Unicore Communications of China is a high-precision multi-frequency RTK module for all satellite systems in an LGA package of 17 x 22 x 2.6 mm, based on Unicore's NebulasIV SoC. It is not assigned to a drone class but is a building block for makers of flight modules and in-house designs.

The chip has 1,408 channels and handles GPS, GLONASS, Galileo, BeiDou, QZSS, NavIC and SBAS, among others GPS L1C/A, L1C, L2C, L2P(Y) and L5, BeiDou B1I, B3I, B1C, B2a and B2b, GLONASS G1, G2 and G3, Galileo E1, E5a, E5b and E6, QZSS up to L6 and NavIC L5. For RTK Unicore states 0.8 cm + 1 ppm horizontally as RMS, a spread measure covering roughly two thirds of the measurements that cannot be compared directly with the CEP figures of other modules. PPP, that is positioning with corrections from a provider, reaches 5 cm, and the position without corrections 1.5 m. The rate is 50 Hz. Connection is through three UARTs; SPI, I2C and CAN are available only with special firmware. NMEA 0183, the Unicore format and RTCM 3.x are spoken. The chip weighs 1.88 g.

PPP needs convergence time before it reaches its accuracy and does not work with the immediacy of a nearby RTK base. A chip is not an aircraft: the duties of the EU drone regulation arise at the aircraft, where geo-awareness and remote identification (from class C1) rest on the GNSS position that such a receiver supplies. Correction data come from your own base, a radio link or an NTRIP service.

For selection it matters whether the firmware offers the required interface, above all for CAN. The UM980 has only one antenna; for heading from two antennas there is the sister variant. Antenna, ground plane and distance from transmitters decide the result, and the firmware is kept up to date.