ARK Electronics GPS

The ARK GPS from US maker ARK Electronics is an open-source DroneCAN GNSS module for medium-class multicopters. It is built on the u-blox NEO-M9N and adds a Bosch BMM150 magnetometer, a BMP388 barometer, an IMU, a buzzer and a safety switch to the receiver. The module is built in the USA.

The M9N is a single-band receiver: it uses the L1 band and handles GPS, GLONASS, Galileo and BeiDou at the same time. It does not do RTK. The accuracy figure of 1.5 m belongs to the chip, not to ARK: for the NEO-M9N u-blox states 1.5 m CEP with SBAS, the radius containing half of the measurements; SBAS is a correction service delivered by satellite. ARK describes the module's accuracy as metre class. Connection is through two DroneCAN ports (JST-GH, 4-pin) and a debug connector. The module weighs 16 g.

Metre class is enough for navigation, attitude control and the zone warning that belongs to geo-awareness. For the EU classes C1 to C3, geo-awareness and remote identification are mandatory, and both rest on the GNSS position that such a module supplies. Anyone who will later need centimetre accuracy chooses an RTK module straight away, because a single-band module cannot be upgraded. Two DroneCAN ports allow further CAN devices to be daisy-chained.

For selection, an autopilot with a CAN port and DroneCAN support counts. The module belongs on a mast, far from power leads and motors, so the compass stays quiet; it is calibrated after installation. The barometer in the module reacts to air movement, so it should sit shielded from propeller wash. The safety switch is part of arming and must be within reach. Upkeep includes the CAN node firmware and a look at the small 4-pin connectors.