VTX & Receiver Module FPV Drone

A VTX (which stands for Video Transmitter) is a crucial component in an FPV (First Person View) drone. Its primary function is to wirelessly transmit the video signal captured by the drone's FPV camera to the pilot's FPV goggles (or a monitor).

Here's a more detailed breakdown of what a VTX is and how it works for FPV drones:

What a VTX Does:

  • Video Capture to Radio Signal: The VTX takes the video feed (either analog or digital, depending on the system) from the drone's camera. It then converts this video signal into a high-frequency radio signal.

  • Wireless Broadcast: This radio signal is then broadcasted through an attached antenna on the drone.

  • Reception by Pilot: The pilot wears FPV goggles (which contain a Video Receiver, or VRX) or uses a ground station monitor. The VRX receives the radio signal from the VTX and converts it back into a video image, displayed for the pilot. This provides the immersive "first person" view from the drone.

Key Characteristics and Features of a VTX:

  • Frequency: Most FPV VTX operate on the 5.8 GHz frequency band. This band is popular because it allows for relatively small antennas and offers a good balance between range and signal penetration in typical FPV environments. Other frequencies (like 1.2 GHz or 2.4 GHz) exist for specific long-range applications.

  • Transmit Power (mW): This refers to the strength of the broadcasted signal, measured in milliwatts (mW).

    • Higher mW usually means greater range and better penetration through obstacles (like trees or buildings).

    • Common power levels include 25mW (often used for racing or close-range flying to minimize interference with other pilots), 200mW, 400mW, 600mW, and sometimes higher.

    • Regulations: The maximum legal transmit power varies by country and region (e.g., in the UK and EU, 25mW is often the limit for unlicensed use in some categories).

  • Channels and Bands: Within a frequency band (like 5.8 GHz), there are multiple channels (specific frequencies) that can be used for video transmission. This is vital for multiple pilots flying together to avoid signal interference. Modern VTXs often support many channels across several "bands" (groups of channels).

  • Antenna Connector: The VTX has a connector (e.g., SMA, RP-SMA, UFL/IPEX) for attaching the video antenna.The type and quality of the antenna significantly impact video quality and range.

  • Input Voltage: VTXs require power, usually supplied directly from the drone's main battery or a voltage regulator (BEC) on the flight controller.

  • Pit Mode: A very useful feature that allows the VTX to transmit at a very low power (e.g., 1mW). This is used when pilots are setting up their drones or waiting to fly, preventing them from interfering with other pilots who are already in the air.

  • SmartAudio / Tramp Protocol: Many modern VTXs can be configured wirelessly via the flight controller using protocols like SmartAudio (TBS) or Tramp (ImmersionRC). This allows pilots to change frequency, power, and other settings directly from their remote controller or OSD (On-Screen Display) in their goggles, without needing to physically access the VTX.

In summary, the VTX is the essential link that provides the pilot with the real-time visual information from the FPV drone, enabling precise control and an immersive flight experience.