# Telemetry Radios

Telemetry Radios can (optionally) be used to provide a wireless MAVLink connection between a ground control station like _QGroundControl_ and a vehicle running PX4. This makes it possible to tune parameters while a vehicle is in flight, inspect telemetry in real-time, change a mission on the fly, etc.

PX4 supports a number of types of telemetry radios:

* [SiK Radio](telemetry/sik_radio) based firmware (more generally, any radio with a UART interface should work).
  * [RFD900 Telemetry Radio](telemetry/sik_radio/rfd900_telemetry)
  * [HolyBro SiK Telemetry Radio](telemetry/sik_radio/holybro_sik_radio)
  * ~~_HKPilot Telemetry Radio_~~ (Discontinued)
  * ~~_3DR Telemetry Radio_~~ (Discontinued)
* [Telemetry Wifi](telemetry/telemetry_wifi)
* [Microhard Serial Telemetry Radio](telemetry/microhard_serial)
  * [ARK Electron Microhard Serial Telemetry Radio](telemetry/microhard_serial/ark_microhard_serial)
  * [Holybro Microhard P900 Telemetry Radio](telemetry/microhard_serial/holybro_microhard_p900_radio)
* CUAV Serial Telemetry Radio
  * [CUAV P8 Telemetry Radio](telemetry/cuav_p8_radio)
* XBee Serial Telemetry Radio
  * [HolyBro XBP9X Telemetry Radio](telemetry/holybro_xbp9x_radio) (Discontinued)

PX4 is protocol compatible with [SiK Radio](telemetry/sik_radio) and will generally work out of the box (though you may need to change/use an appropriate connector).

WiFi telemetry typically has shorter range, higher data rates, and makes it easier to support FPV/video feeds. One benefit of WiFi radios is that you only need to purchase a single radio unit for your vehicle (assuming the ground station already has WiFi).

:::note PX4 does not support connecting an LTE USB module to the flight controller (and sending MAVLink traffic via the Internet). You can however connect an LTE module to a companion computer and use it to route MAVLink traffic from the flight controller. For more information see: [Companion Computer Peripherals > Data Telephony](../../companion_computer/companion_computer_peripherals#data-telephony-lte). :::

## Allowed Frequency Bands

Radio bands allowed for use with drones differ between continents, regions, countries, and even states. You should select a telemetry radio that uses a frequency range that is allowed in the areas where you plan on using the drone.

Low power [SiK radios](telemetry/sik_radio), such as the [Holybro Telemetry Radio](telemetry/sik_radio/holybro_sik_radio), are often available in 915 MHz and 433 MHz variants. While you should check applicable laws in your country/state, broadly speaking 915 MHz can be used in the US, while 433 MHz can be used in EU, Africa, Oceania, and most of Asia.
