What is a Radio Transmitter and a Radio Receiver?

Have you ever wondered how these drones glide all so smoothly in the air or soar different heights in the bright blue sky? How do they follow the commands of the drone controller? If you plan to fly drones, you should be well aware of how it is controlled. Worry not if you don’t have such a clear understanding at the moment. Because we have got your back. Let’s now discuss, in depth, about the two very vital components of your multirotor drone. Yes, we are talking about FPV Drone Radio Transmitter (Tx) and Radio Receiver (Rx).

Before digging into these components, let’s first comprehend how can an individual communicate wirelessly with the drones. We achieve this using radio waves. Radio waves are an invisible wave form on the electromagnetic spectrum. For radio to work, one must have a transmitter to send the messages and a receiver to get those messages. At a rudimentary level, this is how one is able to remotely control an aircraft. More precisely, the transmitter and receiver need to be tuned to the same frequency. Thus, a FPV Drone Radio Transmitter is an electronic device that helps in translating the pilot’s commands into movement of the multirotor.

A FPV Drone Radio Transmitter conveys commands via channels. Each channel corresponds to an individual action being transmitted to the aircraft. The four main inputs are Throttle, Yaw, Pitch and Roll. Gimbals are those sticks that translates an input provided by a pilot into its digital equivalent that can be easily transmitted to the radio receiver.

image credits : oscarliang

Hall Effect Gimbal (digital) and Potentiometer type Gimbal (analogue) are the two types of gimbal. Mode, on the other hand, mode determines the aircraft movement that is assigned to a particular stick movement. Hence, one must choose a “mode”, while purchasing an FPV Drone Radio Transmitter, that they are most likely to prefer while flying.

 image credits : getfpv

An FPV Drone Radio Transmitter most commonly makes use of the following frequencies: 27MHz, 72MHz, 433MHz, 900MHz, 1.3GHz and 2.4Ghz. 433Mhz, 900Mhz and 1.3GHz are usually used in long range FPV and RC systems. Now, let’s understand what an openTX is. OpenTX is an open source custom firmware made for RC radio transmitters that is compatible with the following radios: FrSky Taranis X9D, Q7X, X9E; FrSky Horus X10, X12; Turnigy 9X; FlySky 9X. OpenTX  can store a huge number of models on the radio, even more if they are stored on the Micro SD card.

Telemetry is the data that is transmitted from the Radio Receiver back to the Radio Transmitter. It usually contain a variety of information, usually depending on the type of radio and flight controller. The most important pieces of information are battery voltage reading, current draw and Radio Signal Strength Indication.

Now, a radio receiver is a device that receives the commands that are transmitted by the radio transmitter.

image credits : getfpv

It is capable of sending data back to transmitter. It has a redundancy function wherein there are two receiver connected together and if one loses connection, the second one takes over. Radio communication protocols can split into two primary groups: TX Protocols between Radio Transmitter and Radio Receiver and RX Protocols between Radio Receiver and Flight Controller. A Radio Transmitter will only transmit signals with a Radio Receiver if and only if the two are binded. This process can be done by initiating the bind process on the Radio and then pressing the BIND button on the receiver.

image credits : getfpv

Attached by the U.FL connectors or soldered directly to the receiver’s main board are the receiver antennas that are made of coax cable. They are usually manufactured with two antennas to ensure maximum reception. Radio receivers are available in different shapes and sizes. Smaller ones are best suited for small multirotors where there isn’t much available space for mounting various hardware whereas bigger ones can be used for more comparatively bigger and spacious multirotors.

We recommend you to purchase a Radio Transmitter of a premium quality so that is lasts as long as your interest in this domain lasts. Just make sure the transmitter and the receiver are compatible with each other. That’s a wrap. We hope you were able to develop concepts. Feel free to checkout some of our other blogs. Till then, happy learning.

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