On a UAV, avionics is everything that carries command, video and position between the aircraft and the ground. The control link, the video downlink, the RTK/GNSS receiver, the gimbal payload, and the autopilot that ties them together. Look at each part on its own and it’s just a number on a datasheet. Put them together and they decide whether the aircraft is flyable at all.
Quick answer: Avionics is everything that carries command, video and position between the aircraft and the ground: the control link, the video downlink, the RTK/GNSS receiver, the gimbal payload and the autopilot that ties them together. On industrial aircraft the control link is usually dual-band, 2.4GHz and 5.8GHz, so the feed keeps going when one band gets congested. The Skydroid G and H families cover that range from the compact G11 up to the H30, with the T12 handling the transmitter-first case, and the G20 the ground-station case most industrial customers land on. Build in order: link, positioning, payload, autopilot. See our Skydroid systems page and the ground station guide.
| Subsystem | What it carries | What we fit | Build order |
|---|---|---|---|
| Control link | Commands to the aircraft | G11 to H30 controllers, or the T12 | 1 |
| Video downlink | Image and flight data | Built in on G-series, or YL20 / YL50 boxes | 2 |
| RTK / GNSS | Position | Local base or network corrections | 3 |
| Gimbal payload | The deliverable | C12 dual-light, C20 23x zoom | 4 |
| Telemetry | Autopilot status | Separate radio on autonomous missions | Runs alongside 1 |
| Autopilot | Ties the rest together | S3 open source, S3-A with ArduPilot firmware | Last |
This page is the index. It walks through the four subsystems that matter, the order to choose them in, then points you at the deeper articles for each family: control links, range, ground stations, RTK and gimbal cameras. If you already know the mission and just want the sequence, jump to the build order further down.
The four subsystems on a working UAV
Control link. The radio that carries stick input and telemetry between the ground and the flight controller. It’s the one link the aircraft can’t afford to lose.
Video downlink. A separate radio path that carries the camera feed back to the operator or to a ground station. On industrial aircraft it’s usually dual-band, 2.4GHz and 5.8GHz, so the feed keeps going when one band gets congested.
Positioning. GNSS for a coarse fix, RTK or network corrections when the mission needs centimetres instead of metres.
Payload. The gimbal and its camera, which is where the flight actually earns its keep.
Underneath all four sits the autopilot. It reads the links, the position and the pilot’s input, then turns them into motor commands.
Control link first: the remote controller
Everything else gets designed around the control link, because that’s the one that can’t fail. A remote controller is a radio, an antenna, a battery, and these days a small computer with a screen. Pick your controller and you’ve set the frequency plan, the protocol, the range ceiling and how many telemetry channels the rest of the system gets to play with.
The Skydroid G and H families cover that whole range, from the compact G11 up to the H30, with the T12 handling the transmitter-first case. What goes into picking one, dual-band versus single-band, handheld versus integrated screen, and how range really behaves, is set out in the Skydroid controller and video link guide.
Fly one aircraft on a fixed mission and a simple handheld controller is plenty. Fly several airframes, or need to relay through a repeater, and the choice starts to matter a lot more. That’s why the relay case has its own article.
The video downlink, and why range is the hard part
A video link is a bandwidth problem first, a range problem second. HD video needs tens of megabits. Telemetry needs kilobits. Different radios, different jobs. Pair a long-range control link with a short-range video link and you’ve built an aircraft you can command but can’t see.
Closing that gap is where antennas, relays and line of sight turn into real engineering. The full treatment is in UAV data link range, and the specific case of repeating a feed past a hill or beyond the horizon is in the video transmission relay guide.
Then there are aircraft that carry video but aren’t flown by an operator watching a screen: boats, robotic dogs, tethered platforms. For those, the video transmission boxes YL20 and YL50 handle the downlink on their own, with no controller attached.
Ground stations: when the controller becomes a workstation
Past a certain mission complexity, a handheld controller stops being enough. Survey, inspection and mapping work wants a screen big enough to plan a route, an Android computer to run the flight app, and enough radio to hold the link while the operator stares at the map instead of the aircraft.
That’s a ground station, and the G20 is the one most of our industrial customers land on. Screen size, brightness, processing and the built-in video receiver vary a lot across the range, so we cover the trade-offs in the drone ground station buyer’s guide.
RTK and positioning
Standard GNSS gives you a few metres of accuracy. Fine for flying a field, useless for mapping one. RTK pulls that down to centimetres by comparing the aircraft’s raw satellite measurements against a reference, either a base station you set on the ground or a correction stream delivered over the network.
That correction path has its own demands. It has to be reachable from the aircraft, and it has to arrive fast enough to be useful. Which of the two methods suits a given job, and what each one costs you in setup time, is the subject of RTK base station versus network RTK. The wider question, how positioning, gimbal and autopilot get integrated on one aircraft, is in RTK, gimbal and avionics integration, and the hardware sits under Avionics System.
A local base is the Skydroid RTK base station. It trades coverage for freedom from a network subscription.
Gimbal payloads
The gimbal is what the flight was for. A thermal sensor and an optical zoom camera answer different questions about the same asset, and which one you pick depends on the target and the detail it needs, rather than the budget. The C12 dual-light gimbal carries both on one three-axis head. The C20 goes the other way, with 23x optical zoom for detail at distance.
The comparison, including how the sensor you choose interacts with stability and power draw, is in thermal versus zoom gimbal cameras. The catalogue sits under Camera/Gimbal Series.
Telemetry radios: the quiet subsystem
Between the control link and the video link sits telemetry, the low-bandwidth channel that carries flight data, GPS position and status to the ground app. It’s easy to overlook. Right up until the autopilot stops taking commands. Frequency, latency and how a telemetry radio pairs with the video downlink are covered in telemetry radios for UAVs.
The autopilot under all of it
Every subsystem above reports to the flight controller. It reads the command stream coming in on the control link, the video rides along separately, and it eats the RTK corrections to hold position. The S3 runs open-source firmware for UAV, USV and UGV builds. The S3-A ships with custom ArduPilot firmware for airframes that need a tuned stack straight out of the box.
The order to build in
Mission first: what has to be seen, from how far, at what accuracy. Then the control link, because that sets the frequency plan. Then the video downlink, sized to the range the mission implies. Then positioning, picked from the accuracy you need. Then the gimbal payload, sized to what has to be captured. Then the autopilot that flies the whole thing. Build in that order and the subsystems reinforce each other. Build in any other order and you’ll usually end up replacing the radio twice.
Frequently asked questions
Do I need a separate video transmitter if my controller has a screen?
Not always. Plenty of Skydroid controllers carry video and control in the same box. You only need a separate downlink when the video has to travel further than the control link or reach a second location through a relay, as we explain in the relay and antenna guide.
Is RTK always worth the extra setup?
No. It earns its keep when the mission needs centimetre repeatability: mapping, survey, precise spray. For general inspection work standard GNSS is usually enough, which is the comparison in our RTK guide.
Can I run two different radios on one aircraft?
Yes, and it is perfectly normal. Control, video and telemetry usually sit on different bands. What matters is spacing the antennas far enough apart that they do not interfere.
What breaks a video link first?
Obstruction and antenna placement, long before transmit power. Line of sight and the antenna you fit decide most of your practical range, which is why we cover it separately in the data link range guide.
Which comes first, the gimbal or the airframe?
Settle the payload’s weight and size first, then size the airframe around it. Fit the gimbal last and you usually end up over weight or short on flight time.
Tell us the mission, the range you need and the accuracy the result has to hold, and we will match the controller, downlink, RTK and gimbal around it. The range is on our Skydroid systems page, with the layer-by-layer method in the data link range guide.
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