Telemetry is the quiet one. It carries no video, it barely earns a line in a spec sheet, but it’s the channel your autopilot uses to tell you where it is, what it’s doing and what’s gone wrong. When it fails, the aircraft doesn’t drop out of the sky. It just stops telling you anything. That’s often worse.
Quick answer: Telemetry carries no video. It is the channel your autopilot uses to report position, state and faults, so when it fails the aircraft keeps flying but stops telling you anything, which is often worse. The band trades range for bandwidth: 433, 868 and 915MHz travel furthest at a given power where regulations allow, 2.4GHz is fine for shorter-range links on an aircraft already carrying a 2.4GHz control link, and dual-band 2.4/5.8GHz buys resilience. Telemetry needs kilobits where video needs megabits, so they belong on separate links, and telemetry usually reaches further than the video. See the avionics guide and the data link range guide.
| Band | Reach at a given power | Bandwidth | Typical use |
|---|---|---|---|
| 433 / 868 / 915 MHz | Longest, where regulations allow | Low | Long-range telemetry |
| 2.4 GHz | Shorter | Moderate | Aircraft already carrying a 2.4GHz control link |
| Dual-band 2.4 / 5.8 GHz | System dependent | Higher | Resilience when one band is congested |
| Video link | Shorter than telemetry | Megabits | Image downlink |
This article covers what telemetry carries, how the band you choose changes range and latency, and how to pair the telemetry link with the control and video radios on the same aircraft.
What telemetry actually carries
Telemetry is a low-bandwidth link. It moves flight-controller data in MAVLink-style messages: attitude, position, battery state, mode, and command acknowledgements. The data rate is measured in kilobits per second, not megabits, which is exactly why telemetry radios are small and the video downlink isn’t.
The catch is that range comes down to obstructions and antenna setup rather than bandwidth. The upside is that you can afford to make it tough, because it costs so little capacity to do it.
Frequency bands and what they buy you
433 / 868 / 915 MHz. Lower-frequency bands bend around obstacles better and travel further at a given power, which is why long-range telemetry tends to live here. You pay for that in bandwidth: enough for telemetry, not for video. The exact band is also regulated by region.
2.4 GHz. More bandwidth and widely licence-free, but poorer penetration and more congestion from Wi-Fi. Fine for shorter-range telemetry on an aircraft that also carries a 2.4GHz control link.
Dual-band 2.4 and 5.8 GHz. This is the route most Skydroid systems take, using the lower band for control margin and the higher for video bandwidth. The G12, the T12 and the H30 work this way.
Range, latency and bandwidth: pick two
Every link trades these three against each other. Long range at high bandwidth needs either more power or a directional antenna. Low latency at long range needs a clean path. The usable combination is decided by the mission. A survey aircraft tolerates some latency on its data link, because it’s flying a pre-planned route. A manually flown aircraft needs the control link tight and immediate.
That’s why control and telemetry are often carried on different bands with different priorities, rather than crammed into one link.
Pairing the control link with the video downlink
The classic mistake is to size the control link for the mission and ignore the video link, ending up able to command an aircraft you can’t see. The second mistake is to put both on the same band and antenna, where they interfere with each other.
The fix is to plan the three links together: control and telemetry on one frequency plan, video on another, with physical antenna separation and matched polarisation. How much range each link needs, and what limits it, is covered in UAV data link range, and the controller side is in the Skydroid controller and video link guide.
Where a link has to be pushed further, a repeater such as the TR01 extends it without changing the radios at either end.
Antennas and mounting
Telemetry antennas are small, which is exactly why they’re so easy to place badly. Keep yours away from the video antenna and away from carbon structure, because carbon is basically a shield at these frequencies. Mount it where it has a clean path to the ground, and keep the ground end off the controller’s own body, where your hand can block it.
Firmware and autopilot pairing
Telemetry only works if both ends speak the same protocol. So before the first flight, confirm the aircraft’s flight controller and the ground app agree on the message set and the baud rate, and check the radio against the band plan for your region. The S3 autopilot’s telemetry configuration is the reference point for most of our builds, and the G20 ground station is the common ground end.
Frequently asked questions
Do I need a separate telemetry radio if my controller carries data?
Not always. Plenty of Skydroid controllers carry control and telemetry together. You only need a separate radio when the data link has to run on its own, such as an autonomous mission beyond control range, as the avionics guide explains.
What frequency is best for long-range telemetry?
Lower bands such as 433 or 915MHz travel further at a given power, as long as your region’s regulations allow them.
Can telemetry and video share one radio?
Not really. Telemetry needs kilobits and video needs megabits, so they belong on different links.
Why did my telemetry drop but the aircraft kept flying?
Because the control link and the telemetry link are separate. Losing telemetry means you have lost visibility, not control. Start by checking antenna placement and separation.
Does telemetry range match my video range?
No. Telemetry usually reaches further because it needs far less bandwidth. Plan each link to the range the mission needs, which is the method in our data link range guide.
Tell us the mission range, whether it is flown manually or autonomously, and which bands you already use, and we will match the telemetry and control links around it. The range is on our Skydroid systems page, with the pillar guide in our data link range guide.
