The Basics of Radio Frequencies
You will notice the use of terms such as 2.4GHZ and 5.8GHZ when describing fpv quadcopter and drone aircraft. Here is what you need to know.
2.4 GHZ – is the radio frequency that most quadcopters use for the connection between the ground transmitter and the aerial vehicle. You may remember that this is is also the frequency that computer wireless networks operate on. This can cause some problems when an area (dense housing, office buildings, etc) has many wireless signals. Loss of control and flyways are just some of the reported problems. Another concern is the quadcopter interfering with it’s own on-board systems. This is due to two separate systems being on many modern quadcopters – one for control of the craft and one for transmitting the video (FPV).
5.8GHZ is another radio frequency used in quadcopters, including certain DJI Phantom models, to avoid two frequencies on the same “band” (in the same realm which may entangle each other).
Here is how the DJI Phantom quadcopters, for example, avoid most of these potential problems.
Phantom 1 – operates the aircraft at 2.4 GHZ. If you decide to add FPV (this is DIY), then you must add it using a 5.8GHZ system, which is readily available.
IF YOU USE A GOPRO OR OTHER CAMERA WITH IT’S OWN WIRELESS SYSTEM, BE CERTAIN TO TURN THE WIRELESS OPTION OFF. Otherwise it will interfere with flight control.
Phantom FC40 – uses a 5.8GHZ control system to fly because it has a separate 2.4GHZ system to beam FPV (pictures, video) to the ground.
Phantom 2 – uses 2.4GHZ to control the drone – because most add-on kits which operators will use to beam back the video FPV are 5.8GHZ.
Phantom 2 Vision and Vision+ – both use 5.8GHZ for the quadcopter control and 2.4GHZ for the FPV, telemetry and smartphone app.
In summary, if you buy a Phantom or other 2.4 GHZ machine without a camera, you must use a different frequency (usually 5.8GHZ) system for the camera to ground communication.
Also note that both of these radio frequencies are considered Line of Sight (LOS) in that they do not function when any barriers are in-between you and your quadcopter. Current rules and best practice requires that your drone be flown where you are able to see it with the naked eye.
The most common frequencies used for video transmission are: 900 MHz, 1.2 GHz, 2.4 GHz, and 5.8 GHz. The use of directional, high-gain antennas increases video range. Sophisticated setups are capable of achieving a range of many miles.
A technical article on FPV is available at Wikipedia.