Holybro H-RTK F9P Helical

The Holybro H-RTK F9P Helical is a multi-band RTK rover with a helical antenna for medium-class multicopters. Chinese maker Holybro uses the u-blox ZED-F9P and adds an LED, a safety switch and an IST8310 compass.

The receiver handles GPS, GLONASS, Galileo and BeiDou. The accuracy figure comes from the chip, not the module maker: for the ZED-F9P u-blox states 0.01 m + 1 ppm as CEP, that is 1 cm at a radius containing half of the measurements, plus 1 mm per kilometre of distance from the base. Several bands let the receiver remove the ionosphere, so the RTK solution arrives sooner and holds up better in poor reception. The module connects to the flight controller through UART, with 10-pin and 6-pin GH connectors as are usual on Pixhawk devices.

Helical antennas usually depend less on a large ground plane than patch antennas and receive low-lying satellites well; in return they pick up reflections from surfaces beside the antenna more readily. That helps on frames with little room, but calls for an open mounting spot. The EU classes apply to the aircraft: from C1 upward geo-awareness and remote ID are mandatory, both resting on the GNSS position. Correction data come from your own base, a radio link or an NTRIP service; without corrections the receiver works like an ordinary GNSS receiver.

For selection, mounting decides: the module belongs on a mast, far from power leads, video transmitter and motors, so the compass stays quiet. The compass is calibrated after installation. The safety switch is part of arming and must sit within reach. Upkeep includes receiver and autopilot firmware and a look at the GH connectors after hard landings.