The radio transmitter, also known as RC controller or TX, is an essential part of flying a drone. This guide provides the basics and things to consider when choosing a transmitter: from channels to mode, to frequency and extra features.
A radio transmitter (TX) and a receiver (RX) are essential tools for getting started with a drone, and a good transmitter can last for many years, even with technological upgrades.
What is a radio transmitter and how does it work?
The radio transmitter (TX) allows you to send commands to the drone via a receiver (RX), connected to the flight controller on board the drone. Flight commands, such as acceleration and maneuvers, are transmitted from the TX to the RX, which executes them in real time.
Main elements for choosing a radio transmitter
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Channels The number of channels defines the number of control functions available on the transmitter. The basic channels are at least 4, necessary for controlling pitch, roll, yaw and throttle. Additional channels can be useful for changing flight modes or activating special functions, such as arming the drone. A radio controller with at least 5-6 channels is ideal for more complete control of the drone.
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Transmitter Modes The radio transmission mode can vary, and the main ones are four: Mode 1, Mode 2, Mode 3 and Mode 4. Mode 2 is the most common, where the left lever controls the accelerator and the right one controls the directional maneuvers. The choice of mode depends on your preferences and comfort of use.
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Budget Radio transmitter prices vary greatly, from budget models starting at around 50 euros to high-end ones that exceed 1000 euros. For beginners, it is advisable to start with an affordable model but with at least 6 channels and good technical support. As you become more experienced, you can choose a more advanced model, with more channels and extra features.
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Transmission Frequency The standard frequency for RC transmitters is 2.4 GHz , an advanced technology that allows "frequency hopping", that is, the automatic switching to another available frequency in case of interference. This ensures a stable and secure connection, but for greater distances it is possible to use frequencies such as 868 MHz or 915 MHz via advanced protocols such as TBS Crossfire or ExpressLRS.
Extra features and functionality
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Hardware and Build Quality Good transmitter hardware features include backlit displays, quality gimbals, memories for different drone models, training modes, and customizable response curves for precise control of movements. Some advanced transmitters support programming and firmware updates to add new features or improve the user experience.
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Ergonomics The comfort of the transmitter is crucial, since you will often be using it for extended flight sessions. Consider ergonomics based on the size of your hands, the layout of the sticks and switches, and the weight of the device. Choosing the most comfortable transmitter can be subjective and based on personal preference.
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External RF Module Capabilities Some transmitters allow the use of an external transmitter module, allowing you to connect to other brand receivers or use different frequencies. For example, an external module on a Taranis X9D Plus allows you to use Spektrum receivers or transmit on alternate frequencies like 868 MHz or 915 MHz, offering added versatility.
Radio receivers (RX)
The receiver (RX) is the device connected to the flight controller that receives signals from the transmitter. To work properly, the receiver and transmitter must share the same communication protocol . For example, if you use a transmitter with ExpressLRS (ELRS) protocol, the receiver must also be compatible with ELRS . The same goes for the Crossfire (TBS) protocol: if the TX is TBS Crossfire, the receiver must support Crossfire to ensure a stable and secure connection.
Some of the more common protocols include:
- ExpressLRS (ELRS) : Open-source protocol with frequencies on 2.4 GHz and 868/915 MHz, known for low latency and long range.
- TBS Crossfire : 868/915MHz protocol, widely used for long-distance flight due to stable connection and extended range.
- FrSky ACCST and ACCESS : Popular in 2.4GHz systems, especially popular among pilots for compatibility with a wide range of FrSky receivers.
Some transmitters allow you to connect multiple receivers, each configurable with specific settings for different drones. It is important to note that TX and RX compatibility are not interchangeable between different brands and protocols, so it is essential to choose a receiver that supports the specific protocol of your transmitter.
Telemetry functionality
Telemetry is a useful feature that allows the RX to send flight data to the TX, such as RSSI signal, battery voltage and other parameters, useful for monitoring the condition of the drone during flight.
Examples of recommended transmitters
Here are some popular and recommended transmitters for FPV pilots:
- Radiomaster TX16S : Versatile and compatible with many external modules, it offers excellent value for money for intermediate and advanced level pilots.
- TBS Tango 2 : Compact and designed specifically for the Crossfire protocol, it is perfect for those looking for long-distance performance.
- Radiomaster Boxer : Ideal for pilots who want a powerful and portable transmitter, with all the main features and good comfort.
- Jumper T-Lite : Compact and lightweight, suitable for those looking for a portable and versatile solution with multi-protocol support.
Conclusion
Investing in a good radio transmitter is essential for those who want to fly drones with ease and safety. Advanced models such as the Radiomaster TX16S or the TBS Tango 2 offer high-level features for the most demanding pilots. Choose your TX carefully, as a good transmitter can accompany you for many years in this exciting hobby.
