Video Transmitter (VTX)
The Video Transmitter (VTX) takes the video signal from your FPV camera and broadcasts it wirelessly to your goggles. It’s a critical link in the FPV chain — VTX quality, power level, and antenna choice directly affect your video range and quality.
Analog VTX
Section titled “Analog VTX”An analog VTX broadcasts the camera’s composite video signal on a specific frequency in the 5.8GHz band (most common) or 2.4GHz/1.3GHz (for long range).
Power Levels
Section titled “Power Levels”| Power | Range (typical) | Use Case |
|---|---|---|
| 25mW | 200-500m | Indoor, close range, pit mode |
| 100-200mW | 500m-1km | Park flying, small area |
| 400-600mW | 1-2km | Freestyle, open area |
| 800mW-1W+ | 2-5km+ | Long range, behind obstacles |
Start at 200-400mW for most flying. Higher power generates more heat and can interfere with other pilots if you’re at a group fly.
Frequency Bands
Section titled “Frequency Bands”5.8GHz analog VTXs operate across several bands:
- Band A, B, E: Standard bands
- Raceband (R): 8 channels designed to minimize interference when multiple pilots fly simultaneously. The standard for group flying and racing.
- Low band (L): Used by some VTXs for additional channels
When flying with others, coordinate channels to avoid interference. Raceband is designed for this — use it at group events.
Smart Audio / Tramp
Section titled “Smart Audio / Tramp”Most modern VTXs support remote control via a serial protocol:
- TBS SmartAudio: Change VTX power, channel, and band from your OSD or Betaflight without touching the VTX
- IRC Tramp: Similar functionality, different protocol
- Connect to a UART on the FC and configure in Betaflight’s Ports tab
This lets you switch channels and power levels from your goggles using the Betaflight OSD — essential for race events where you need to switch quickly.
Popular Analog VTXs
Section titled “Popular Analog VTXs”| VTX | Power | Size | Notes |
|---|---|---|---|
| TBS Unify Pro32 | 25-800mW | Standard | Rock-solid reliability |
| Rush Tank Ultimate | 25-800mW | 20x20/30x30 | Popular, affordable |
| Foxeer Reaper | 25-800mW | Multiple | Good feature set |
| BetaFPV A03 | 25-400mW | Micro | For whoops/micros |
Digital VTX (Air Unit)
Section titled “Digital VTX (Air Unit)”Digital VTXs encode video digitally before transmission, providing much higher image quality than analog.
DJI O3 / O4 Air Unit
Section titled “DJI O3 / O4 Air Unit”- Integrated camera + VTX (one unit)
- 1080p video feed to DJI goggles
- Built-in DVR recording on the air unit itself
- ~30ms latency
- O4 is the latest generation with improved performance
- Heaviest option (~36g for O3)
Walksnail Avatar
Section titled “Walksnail Avatar”- Camera + VTX available as separate or integrated units
- Multiple size options (full, Mini, Nano)
- Good image quality, improving with firmware updates
- Lighter options than DJI available
HDZero
Section titled “HDZero”- Camera and VTX are separate components (like analog)
- Multiple VTX options from full-power to whoop-size
- ~12ms latency (lowest of any digital system)
- VTX options: Freestyle V2 (25-800mW), Race V3 (25-400mW), Whoop Lite
→ See Digital FPV Systems for full comparison.
Antenna Connection
Section titled “Antenna Connection”VTXs connect to antennas via:
- UFL/IPEX: Tiny push-fit connector. Common on lightweight VTXs. Fragile — handle carefully, don’t repeatedly unplug.
- MMCX: Small but more robust than UFL. Growing in popularity.
- SMA: Threaded metal connector. Most durable but heaviest. Common on standalone VTXs.
Always connect the antenna before powering on the VTX. Running a VTX without an antenna can instantly damage it — the RF energy has nowhere to go and burns out the transmitter.
→ See Antennas for antenna types and selection.
VTX Installation
Section titled “VTX Installation”Mounting
Section titled “Mounting”- Mount on the FC stack using standoffs (20x20 or 30x30 mounting pattern)
- Or mount externally with double-sided tape or zip ties
- Keep away from the FC gyro to minimize electrical interference
- Route the antenna wire so it exits cleanly at the rear of the frame
Wiring (Analog)
Section titled “Wiring (Analog)”- VCC: Power input. Check the VTX’s voltage range — some accept battery voltage directly (e.g., 7-26V), others need regulated 5V or 9V.
- GND: Ground
- Video In: From the camera’s video output
- Smart Audio/Tramp: To a UART TX pad on the FC (for remote control via OSD)
Heat Management
Section titled “Heat Management”VTXs generate heat, especially at higher power levels. Tips:
- Don’t enclose the VTX with no airflow
- Some pilots add small heatsinks
- Power down (pit mode) when not flying
- Don’t run maximum power for extended periods on the ground