Quick Answer
A complete long-range drone data link requires an air modem connected to your flight controller, a ground modem connected to your PC or ground station, two antennas, compatible cables, and a power supply. For RC control beyond 2.4 GHz range, add a TXMOD module to your transmitter. The simplest way to get started is with a pre-matched bundle that includes everything you need.
What Is a Data Link?
A data link is the radio connection between your drone and your ground station. It carries telemetry, commands, and waypoint data using the MAVLink protocol over 868 MHz (EU) or 900 MHz (US). This is separate from your video feed and separate from your RC control link. Think of it as the text-messaging system between your aircraft and your computer.
RFdesign modems like the RFD 868x pair with each other out of the box. One goes on the aircraft, one stays on the ground. They communicate on the same frequency and handle MAVLink streams automatically once wired up correctly.
Components You Need
| Component | What It Does | Notes |
|---|---|---|
| Air modem | Sits on the drone, sends/receives telemetry | Connects to flight controller TELEM port |
| Ground modem | Sits at your ground station | Connects to PC via USB or serial |
| 2× antennas | Screw onto each modem (SMA connectors) | Match polarity (both LHCP or both RHCP) |
| 2× cables | Connect modems to flight controller / PC | Must match modem generation (x-series or ux-series) |
| TXMOD (optional) | RC control via the same 868/900 MHz band | Pairs with ground modem, goes in your transmitter's JR bay |
How Everything Connects
Telemetry link: The air modem wires into your Pixhawk flight controller's TELEM2 port using a Pixhawk 2 telemetry cable. The ground modem connects to your ground station laptop via USB. Once powered on and paired, MAVLink data flows both ways. Your ground control software (Mission Planner, QGroundControl) shows live telemetry and lets you send commands.
RC control link: The TXMOD plugs into your transmitter's JR-module bay and pairs with the ground modem. RC stick inputs are forwarded over the same 868/900 MHz radio as a separate MAVLink stream. This gives you full control of the aircraft even when your standard 2.4 GHz RC link runs out of range. For more detail on how TXMOD works, read our TXMOD explained guide.
Picking the Right Set
Use a bundle. Bundles are the easiest route because every component is guaranteed compatible. The RFD 868x bundle includes a matched pair of modems, cables, and antennas. If you also need long-range RC control, the TXMOD adds that capability on top of the same ground modem.
Choose your frequency. In the UK and EU, use 868 MHz modems (868x or 868ux). In the US, use 900 MHz. Using the wrong frequency for your region is illegal and will cause interference with licensed equipment.
Match your cables. The x-series modems (868x, 900x) use different connector cables than the ux-series (868ux, 900ux). A 30cm multi-cable for RFD900x/RFD868x works with x-series modems. If you are unsure which generation you have, check our RFD module comparison article.
What to Buy
- RF Design RFD 868x Long Range Telemetry Modem Bundle — matched pair with cables and antennas (EU)
- RFD 868 TXMOD — add long-range RC control to your transmitter
- RFdesign Long Range Telemetry & Radio Modems — full range of modems, bundles, and accessories
- Wireless/Telemetry — all telemetry radio options including Microhard and RFdesign
FAQ
Q: Is the TXMOD the same as a telemetry modem?
A: No. A telemetry modem sends MAVLink data between your drone and ground station. The TXMOD sends RC stick inputs from your transmitter to your aircraft. They work on the same band but carry different data streams. The TXMOD needs a ground modem to function.
Q: Can I use any antenna?
A: Use SMA-threaded antennas rated for 868 or 900 MHz. Both modems must use the same polarisation. For more detail, see our antenna selection and range testing guide.
Q: Do I need a data link if I already have ELRS or Crossfire?
A: ELRS and Crossfire handle RC control, not telemetry. A data link gives you live flight data, waypoint management, and two-way MAVLink communication with your flight controller. They serve different purposes.