SiK Radio
SiK radio is a collection of firmware and tools for telemetry radios.
PX4 is protocol-compatible with radios that use SiK. SiK Radios often come with appropriate connectors/cables allowing them to be directly connected to Pixhawk Series controllers (in some cases you may need to obtain an appropriate cable/connector). Typically you will need a pair of devices - one for the vehicle and one for the ground station.
Hardware for the SiK radio can be obtained from various manufacturers/stores in variants that support different range and form factors.
Vendors
- Holybro Telemetry Radio
- HolyBro SiK Long Range
- RFD900 Telemetry Radio
- ThunderFly TFSIK01 Telemetry Radio
HKPilot Telemetry Radio(Discontinued)3DR Telemetry Radio(Discontinued)
Setup/Configuration
The ground station-based radio is connected via USB (essentially plug-n-play).
The vehicle-based radio is connected to the flight-controller's TELEM1 port, and typically requires no further configuration.
Link Throughput
The serial baudrate says little about what a SiK link carries over the air. At 57600 baud with the common 64 kbps air rate, a radio carries roughly 2000 B/s with error correction enabled and about twice that without.
MAV_0_RATE caps what PX4 sends on TELEM1. Setting it above what the link carries does not make telemetry faster: the radio drops packets instead, which shows up as MAVLink loss and makes parameter and log downloads slow or unreliable. Lower it if you see loss.
Two AT commands report the radio's own limits: ATI5 lists the settings, including S2:AIR_SPEED and S5:ECC, and ATI6 reports max_data_packet_length - the largest MAVLink packet the radio sends in one piece. Error correction roughly halves both the throughput and that packet size.
Firmware Update
Hardware sourced from most vendors should come pre-configured with the latest firmware. You may need to update older hardware with new firmware, for example to gain support for MAVLink 2.
You can update the radio firmware using QGroundControl: QGroundControl User Guide > Loading Firmware.
Advanced Setup/Configuration
The Development section has additional information about building firmware and AT-command based configuration. This should not be required by non-developers.