Holybro M9N GPS

The Holybro M9N GPS is a standard single-band GNSS puck with a compass for Pixhawk autopilots and medium-class multicopters. Chinese maker Holybro uses the u-blox NEO-M9N and an IST8310 compass. The housing has a diameter of 50 mm.

The module receives GPS, GLONASS, Galileo and BeiDou in the L1 band (GPS L1, Galileo E1, GLONASS L1, BeiDou B1, plus SBAS L1 and QZSS L1). It does not offer RTK. Holybro states 1.5 m CEP, the radius containing half of the measurements. The rate is 25 Hz. Connection is through UART to the autopilot's GPS port. The module weighs 32 g with housing.

A single-band module uses only one frequency band and cannot remove the ionosphere; metre class is the result, but it is enough for navigation, attitude control and zone warning. For the EU classes C1 to C3, geo-awareness and remote identification are mandatory, both resting on the GNSS position. Anyone who will later need centimetre accuracy chooses an RTK module straight away. The M9N is a widespread chip in GPS units for drones.

For selection it matters that the module belongs on a mast: the compass sits in the housing and needs distance from power leads, motors and batteries. It is calibrated after installation and checked after larger changes of location. The puck is fixed so that the antenna has a clear view upward and no metal surface shields it. Upkeep includes checking the cable for chafing and the connector for a firm seat, especially after hard landings.