In this article we are going to take a look at the technology and commonly used radio controllers for flying FPV quadcopters. These controllers are often the same products you will find in other RC hobbies. FPV has a special set of needs and requirements that we will cover here.

Component Spotlight: RC Radio Transmitters & Receivers

Below, you'll find all the fundamental information on these controllers and receivers that they connect to. We also help you choose the right radio by providing a wide range of best recommendations for every budget. This article is part of a series that covers the entire concept of quadcopter parts, how they work, and how they come together. For further reading, see the master article: Components & Anatomy of an FPV Quadcopter

Lets get started - jump to a specific section using the table of contents or continue reading below:

Table of Contents

Overview Table of Recommended Transmitters

If you're looking for transmitter recommendations, find the overview table here. For detailed information and a pricing break down, skip down the page.

Radio Channels Price
Spektrum DXe Thumb Spektrum DXe 6 $59.99
Flysky FS-T6 Thumb Flysky FS-T6 6 $55.99
Turnigy Evolution Thumb Turnigy Evolution 8 $67.20
Taranis Q X7 Thumb FrSky Taranis Q X7 16 $120
Spektrum DX6e Thumb Spektrum DX6e 6 $179.99
FrSky Taranis X9D Plus Thumb FrSky Taranis X9D Plus 16 $205
TBS Tango Thumb TBS Tango 10 $249.95
Spektrum DX9 Black Edition Thumb Spektrum DX9 Black Edition 9 $599.99

How Radio Transmitters & Receivers Work

A radio transmitter is the controller you hold in your hand that sends your inputs to your quadcopter. On-board your multirotor a radio receiver is connected to the flight controller. This small circuit board with receives the inputs from your transmitter via small antennas. Those inputs allow your flight controller to make the appropriate speed adjustments to the motors, creating the desired output from the control input.

Radio signal is broadcast out from the transmitter along a specific frequency, most commonly the 2.4GHz band. Modern transmitters have intelligent technology which prevents conflicts when multiple radios are in use simultaneously. The transmitter is bound to a specific receiver which sits on-board the RC craft. The inputs from the radio are assigned a specific channel. Each channel is sent as an input value to the receiver which passes the information along to the brain of the aircraft.

Radio controllers have been used on RC model aircraft since the 1930's, though these types of radio controllers weren't popular until the 1970's. See the Academy of Model Aeronautics for more on the history of radio controlled aircraft.

Radio Transmitters (Tx)

The radio transmitter is the controller that you hold to pilot your copter. There are many brands and options out there for various applications. Because we are talking about flying drones, this article focuses on air-based radio controllers. Lets look at the common features of RC radio transmitters:

Channels

The number of channels a radio translates to the number of controls inputs your radio can send to your receiver. These channels come in the form of control sticks, switches, or dials. Using the FrSky Taranis X9D Plus as an example we have labeled the 16 channels that the radio features:

16 Channel Map of the Taranis Radio

As a bare minimum you need 5 channels to control an FPV quadcopter - 4 channels to control throttle, yaw, pitch, and roll and 1 channel to arm/disarm the copter. Additional channels will be helpful for setup of things like airmode, auto-level modes, buzzers and more. 9 channels or more will cover almost any common FPV setup.

The only un-labeled controls on the above diagram are the trim adjustments which are found below and to the inside of the control gimbals. These trim adjustments adjust the center point of the control sticks. They do not transmit information, they adjust the setting of the radio so therefore they are not channels.

Gimbal Control Modes

When you hear someone talk about "what mode" his or her radio is, they are referring to how the 2 control sticks (gimbals) are laid out and configured on the radio. There are 4 modes out there labeled simply as "Mode 1" through "Mode 4". Mode 1 & 2 are commonly used when flying quadcopters, Mode 3 & 4 are rarely seen.

There are two different types of gimbals used in RC radios. We define them as:

  • Centered Control Stick: When inputs are released, this control stick snaps to the center of both X and Y axis'. In our diagrams this is the stick set at the center of the X/Y layout.
  • Throttle Control Stick: When inputs are released, this control stick only snaps to the center of the X axis. It remains where set on the Y axis. In our diagrams this is the stick set at the center of the X axis, but at the bottom of the Y axis.

These control sticks are also called Gimbals. This is the name of the hardware for the control sticks found on RC radios. These are different than gimbals used with cameras.

RC Radio Modes for FPV Quadcopters
Download High Resolution Chart

Mode 1

This mode sees the throttle stick on the right and the centered stick on the left. This setup is less popular than Mode 2.

  • The centered stick controls the pitch or forward/backward tilt on the X axis and the yaw or hinge turns on the Y axis.
  • The throttle stick controls the throttle on the X axis and the roll or left/right tilt on the Y axis.

Mode 2

This mode sees the throttle stick on the left and the centered stick on the right. If you're not sure which Mode to get - go for Mode 2 as it is the most popular.

  • The throttle stick controls the throttle on the X axis and the yaw or hinge turns on the Y axis.
  • The centered stick controls the pitch or forward/backward tilt on the X axis and the roll or left/right tilt on the Y axis.

Mode 3 & 4

You won't find many pilots using mode 3 or 4 to control their quadcopters. These two modes make slight adjustments to the stick layout found in mode 1 & 2.

  • Mode 3 uses the Mode 1 stick layout but swaps Yaw and Roll.
  • Mode 4 uses the Mode 2 stick layout but swaps Yaw and Roll.

Frequencies

For FPV you will almost exclusively find radios using the 2.4ghz radio band. This modern band features a good balance of range and necessary antenna size. Lower frequencies such as 1.3ghz will allow you longer range controls. You won't find many FPV copters using 1.3ghz frequencies.

Most modern radios include a feature called frequency hopping. These protocols look for the cleanest band when in use and remove any potential conflicts that might exist when multiple radios are operated in close proximity. Overall your radio frequency isn't something you need to worry too much about if you are buying a new radio. If you are buying older gear or looking for long range control then it is something to consider.

Computer Connectivity

Taranis Back USB Port
Back of the Taranis showing the USB port.

We are a big supporter of FPV flight simulators. One of the most important factors of training on a sim is using the actual radio you will fly your quadcopter with. How you connect your radio to your computer is always something important to consider. Some radios require an adapter, while others feature a built-in USB port.

Radio Receivers (Rx)

The receiver is a small component that consists of a circuit board, antenna(s), and connectors. This piece of equipment connects to the flight controller (brain) of your copter. It then receives the inputs from your radio and transfers those inputs to the flight controller. Often the receiver can also transmit information about your copter back to the radio through telemetry.

FrSky X4R SB Receiver
FrSky X4R-SB Receiver

Radio Signal & Latency

Above we talked about the frequencies of your radio. When it comes to the receiver you need to consider the protocol that the frequency is using. The protocol you use varies from manufacturer to manufacturer and has an influence on the signal you send. For FPV the biggest impact we see from different radio signals is the latency or time it takes for your inputs to be received. We are always looking for the lowest latency possible.

Using the FrSky protocols on a receiver like the X4R as an example we can compare PPM vs SBUS:

  • PPM is an older generation analogue protocol. The delay is 60ms to 80ms.
  • SBUS is newer digital signal with 10ms to 20ms delay.

Telemetry

Some receivers can send back information to your radio using a feature called telemetry. By setting up telemetry you are able to read all kinds of information about your copter like battery information. You can transmit this information back to your radio live in order to always know the battery levels.

Binding

When you set up your craft you will bind the model on your radio to the receiver. This process connects your transmitter and receiver and only needs to be done once. Once bound your craft will only be controllable by your receiver and will not be interfered with by others flying near you.

Radio Brands & Compatibility

Generally speaking the major radio brands are compatible with their own products. For example FrSky transmitters connect with FrSky receivers. This means your FrSky radio won't be compatible with your Spektrum receiver out of the box. Make sure that you research compatibility. The easiest way to avoid these issues is to buy within the same brand name.

If your radio has a module port, you can also buy receiver modules to fix compatibility issues. For example you can buy the OrangeRX DSMX/DSM2 Spektrum module to plug into your FrSky receiver to control Spektrum based models. This example is commonly used for Tiny Whoop pilots using their Taranis.

Best Radio Transmitters for FPV Quadcopters

Most transmitters can store settings for multiple models. This means the radio can control multiple RC aircraft. You can buy one radio and grow with it. We recommend looking seriously at the options out there and focus more on the features than just the price point. Going with a cheap radio that has to be replaced later is always a bummer. It is better to invest wisely and get the radio you need early on.

It's also important to point out that the FPV market is largely dominated by two radio companies: FrSky and Spektrum. You'll find on of these two brands used by pilots over 95% of the time. Because of this, their products have almost universal support for receivers and built-in hardware. For example you'll find native support for these two brands on hardware like Tiny Whoop flight controllers.

Affordable Entry-Level Radios (Under $100)

Spektrum DXe

Spektrum DXe Radio

With the DXe, Spektrum brought a much needed DSMX capable transmitter to the beginner market. The transmitter is a 6 to 9 channel setup that is configurable for modes 1-4 using switches on the gimbals. You're not going to find high end luxuries like telemetry, but you'll find a solid beginner platform that will let you grow in the FPV hobby without needing to invest due to a limited feature set.

Flysky FS-T6

Flysky FS-T6 Radio

The FS-T6 is the most affordable radio on our list. The radio features a basic 6 channel layout with all the features you need for operating your quadcopter. The additional ability to store up to 20 models makes this a transmitter that will give you some room to grow.

Turnigy Evolution

Turnigy Evolution Radio

The Evolution is an interesting beginner choice because it packs an interesting feature set in a compact package. Turnigy took a step in the direction of video game controllers with this radio and created something interesting. The controller features a small form factor with lots of features. It's the only option in our entry-level list that offers telemetry and a USB port for use with computer simulators.

Mid-Range Radios (Under $200)

FrSky Taranis Q X7

Taranis QX7

The Taranis QX7 is FrSky's answer to the mid-market demand for a feature-packed transmitter. They've stripped some of the unused FPV features from the X9D Plus and packaged it into a new white or black case. You'll find compatibility with Taranis model files, USB and SD card support for OpenTX. Don't expect a high end build quality, but for a first radio the Q X7 is a solid choice that will be well supported and last you for some time to come.

Spektrum DX6e

Spektrum DX6e

The DX6e is the next step up from the DXe. Still a 6 channel radio, the 6e brings some more pro-level features to the table. You'll find support for DSM2 in addition to DSMX. You'll also find telemetry support and a 250 model memory that can be switched without connection to a phone or PC.

High End Radios (Over $200)

FrSky Taranis X9D Plus

FrSky Taranis X9D Plus Radio

The Taranis X9D Plus is the current king of FPV quadcopter radio transmitters. The feature set covers almost every possible requirement you'll run across. 16 channels, telemetry, haptic feedback, integrated battery charger, included and upgradable battery and USB computer connectivity round out the feature set.

While being the most widely used FPV radio transmitter, the Taranis has its weak points. The most common complain is the cheap potentiometer based gimbals (sticks). This problem was answered by FrSky who released the M9 Gimbal upgrade. For ~$40 you can install a much superior set of Hall Effect gimbals and greatly improve your X9D or X9D Plus.

  • Channels: 16
  • Protocol: FrSky X, D, and V8-II Series
  • Price: $205
  • Price w/ M9 Gimbal Upgrade - $246
  • See Product Information

TBS Tango

TBS Tango Radio Transmitter and Video Receiver

Team BlackSheep introduced the Tango as the first radio transmitter + video receiver / monitor all-in-one solution. The result is a relatively affordable and widely compatible solution. You'll find a 10 channel digital transmitter surrounding a video monitor and built-in 5dBi patch antenna. You can use the screen or connect your goggles to the transmitter to watch your flight. The transmitter uses JR modules to connect to a wide range of popular radio receivers.

  • Channels: 10
  • Protocol: Changeable using JR modules: TBS Crossfire, FrSky XJT, Spektrum, Futaba, and Graupner options available.
  • Price: $249.95 without Transmitter Module
  • See Product Information

Spektrum DX9 Black Edition

Spektrum DX9 Black Edition

The DX9 features all the features and luxuries you could ask for as an FPV pilot. You'll find 9 channels, 250 model storage, an included 2000mAh Li-Ion battery, SD card and charger. The price tag here is the highest of all the offerings available, but the quality is top of the line. That quality is why you'll find top level pilots like Skitzo and JohnnyFPV flying the DX9.

Please leave any questions or comments in the section below.

Last updated on January 29, 2017



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