When you are flying multiple drones in the same location, you can start noticing some strange behaviour. Flying with other people is common, but there are some precautions that you need to take to make sure that the interference between the drones and remotes doesn’t cause any significant damage or issues.
Drones can interfere with each other because they all rely on the same wireless communication frequencies. Drones will automatically select the channel with the lowest amount of interference, and connecting with a 5.8 GHz frequency provide you with more channels to avoid interference.
When two drones fly together, they use frequency hopping to avoid interfering with each other’s signals. Even proprietary wireless protocols for remote and wireless connectivity such as DJI’s Ocusync share some frequencies with Wi-Fi and other wireless connectivity particles such as Bluetooth.
Why do drones interfere with each other
There are two types of Wi-Fi typically offered in drone technology. These Wi-Fi offerings are 2.4 GHz and 5.8 GHz. These numbers refer to the frequency at which they can transmit data.
5 GHz frequency provides a much faster communication, but the signal cannot travel as far. 2.4 GHz offers a slower connection but a more stable signal over longer distances. Many consumer-level drones can swap between 2.4 GHz and 5 GHz, and selecting the most appropriate one for your flight mission will reduce the chances of signal interference.
When you throw another drone into the Wi-Fi mix, interference becomes a very common problem. Wi-Fi interference is essentially a radio interference between your remote and drone with another person’s remote or drone.
Drones that use Wi-Fi to transmit data become very sensitive to interference from other sources of radio broadcasting in the same frequency range. The most common source of interference is other, more powerful sources of radio frequencies.
The Wi-Fi interference can cause dropout issues and force your drone to return to home or land. In the worst-case scenario, your drone could lose control and fall uncontrollably out of the sky.
Here are all of the approaches you can take to minimise interference when flying your drone.
What you can do to minimise interference
Suppose you want to fly two or more drones together simultaneously. In that case, you can reduce the amount of interference by standing further away from each other, using a frequency and channel with less interference. You can also make sure that you have a direct line of sight to your drone and stand away from any potential reflectors of Wi-Fi radiations, such as big concrete walls.
Stand far away from each other
Standing far away from each other is one of the easiest ways to minimise the amount of interference between drones.
Wi-Fi signal strength can be a tricky topic. The most accurate way people express it is in milliwatts, but you can end up with a load of decimal places due to the Wi-Fi is due to super low power transmission.
The closer you are to another drone pilot’s remote control, the higher the potential interaction between the Wi-Fi signals.
Signals can interfere by cancelling each other out and causing a high amount of noise to be generated. Standing approximately 10 feet away from another drone pilot is the easiest way to minimise the amount of interference between your drones. This, of course, assumes that you are using the same technology to communicate with your drones.
DJI has been developing proprietary communication software so that it can communicate over much larger distances.
|DJI’s OcuSync||7 km (4.3 miles)|
|DJI’s OcuSync 2.0||10 km (6.2 miles)|
|DJI’s Lightbridge||1.7 km (0.6 miles)|
|Wi-Fi||300 to 2000 m|
|Bluetooth||10 – 100 m|
Use 5.8 GHz frequency
If you are flying multiple drones in the same location, you should consider setting your Wi-Fi connection to 5.8 GHz. This range has significantly more Wi-Fi channels and much less overlap – 24 of these 45 channels do not overlap.
The additional number of channels means that you will be able to fly close to each other with significantly more drones.
You can also fly with more confidence, as channel switching gives the drone more flexibility in choosing a stable channel throughout the flight.
The problem with using 5.8GHz to connect to your drone is that it doesn’t get that far. You may find your drone has an unstable connection if you fly more than 500m away from the remote controller at 5.8GHz. For most drone pilots, this isn’t necessarily a problem.
Choosing 5.8 GHz also allows you to fly in urban areas where Wi-Fi channels are particularly busy.
Use lowest interference channel
In your app, you are likely to be able to monitor all of the channels for interference.
For example, in the DJI GO4 app, you can observe the interference. By selecting the HD option on the app, you can view the signal activity level available on each of the channels. You should with little to no interference. You want a channel with no bar displayed and, ideally, a channel with no bar on either side on the adjacent channels
An example of using this information to choose the best channel on both 2.4 and 5 GHz channels can be seen in the video below.
Many drone pilots choose to exclusively fly in 5.8 GHz mode because of the noisy urban environments that they are flying in.
We recommend that you do not use boosters or powerful remote controls when flying with multiple pilots. Using boosters or powerful remote controls can cause serious interference with the connections of other drone pilots.
The drone signal booster consists of a parabolic mirror that reflects the controller’s signal toward the drone. It can be used to allow you to fly further or to fight signal dropouts in the noisy areas of Wi-Fi and 5G.
Normally, these dishes are foldable and slide onto the drone controller’s antenna. They are easy to transport and provide additional security when flying long distances.
If no one else is using the signal booster, your enhanced power can easily confuse other drones in the area.
The strongest emitter wins. This fact is used in jammer technology to prevent drones from flying near sensitive areas. If you want to know more about whether or not it is possible to jam a drone signal, check out my other article – click here.
Jamming aims to distort the signal to a level at which the receiver cannot completely detect it or cause some system parts to lose their integrity, resulting in a total or partial denial of service between the drone and the controller.
Direct line of sight
Always fly your drone in a direct line of sight. Having a direct line of sight means that you can ensure maximum signal strength between your remote control and the drone.
I have found that even flying behind trees and light foliage has caused significant interference between my controller and the drone.
We are all tempted to sneak around a tree, building, cliff, or other obstacles, but in many countries, the drone’s flight laws and regulations must be within sight of the pilot at all times.
If you end up losing direct line of sight to your drone, you are essentially flying blind.
Flying blind means you can rely 100% on the drone sensors and visual positioning systems to navigate your 3D environment safely. Even for the most experienced pilots, this is a very difficult situation.
You can also lose control of your drone using flying goggles that broadcast real-time first-person video. Using drone goggles means you cannot quickly check the current drone position using the line of sight and should only be used for racing drones or other niche drone applications.
Away from walls and other reflectors
If you are in an urban setting, there are a variety of other surfaces that can unpredictably reflect your Wi-Fi signal.
I sometimes fly my drone with a big concrete wall behind me. This big concrete wall can easily reflect some of the Wi-Fi signals I’m using to communicate with my drone back towards the controller. The reflected Wi-Fi signal can easily cause interference with the signal and become reflected towards other drone pilots.
There are a variety of materials that can easily interfere with your Wi-Fi signal. These include:
- metal – metal is the hardest material to penetrate and can easily reflect and absorb Wi-Fi signals.
- Concrete walls – Wi-Fi does not mix well with concrete walls. The Wi-Fi signal is absorbed by the walls and can also be reflected off their surface.
- Plaster and metal – many modern structures use metal in plaster as a framework for interior and external wars.
- Ceramic tiles – Wi-Fi signals can easily be reflected using ceramic tiles.
- Windows and glass – many modern buildings use a combination of windows and glass, which is a perfect reflector for Wi-Fi signals. Low emissivity windows are one of the worst culprits. They have a very thin metallic film on top to help with energy consumption, and they can reflect even more signals than a clear window.
- Mirrors – any mirrors in the environment are highly reflective. Mirrors have a thin coat of metal on glass and can reflect Wi-Fi signals incredibly effectively.
- Water – any large amount of water in the environment can absorb the Wi-Fi signal and reflect and refract the Wi-Fi signal causing it to become noisier. If you want to know more about flying above water safely, you can check out my other article – click here.
Other strong emitters of radiofrequency in the area can also interfere with any Wi-Fi drone signal.
Dangers of interference
The dangers of having a weak or noisy signal can cause collisions, loss of control, auto-landing or return to home.
If you lose control of your drone when other drones are around, it could result in a collision. As you fly your drone, you must always be careful to stay away from obstructions and other flying objects.
As you are flying, your drone will experience a range of signal strengths from your remote. If your drone accidentally switches to a channel that has already got a drone on it, it will have to make decisions using its autonomous artificial intelligence software.
Even though it is unlikely that your drone will come into contact with another in the area, the likelihood increases if you lose connectivity to the drone due to signal interference or disconnection.
Loss of control
a complete loss of control is a reality if your drone signal becomes weak or noisy. Many of the consumer-level drones now on the market can return to the takeoff position as long as the GPS coordinates have been accurately stored.
If you are not flying a high-level consumer drone, your drone will likely lose control and drift with the wind. Some beginner drones do not have auto stabilisation features and will drift uncontrollably or drop out of the sky if the signal is lost and they are running low on battery.
Always pay attention to the warning signals that pop up on the apps so that you can be aware of any signal issues as they pop up.
Drones that suffer a complete signal loss will often auto land where they are or return home. If your drone decides to land where ever it currently is, you may lose your drone as it could be over water, bushes, or trees.
If your drone lands in an area that is not open to the public, you may be charged with trespassing if the drone automatically lands in a private and secure area.
To ensure that your drone will land safely, you should make sure that the GPS location of the drone has been set accurately upon takeoff and that it does not update throughout the flight. In some drones, you can tell the drone to return to the remote control, which is particularly useful if you have changed location throughout the flight. This change of location typically happens when you are using the drone to track yourself.
Can drones interfere with each other? Summary
In this article, we have gone over everything you need to know about whether or not drones can interfere with each other.
Because drones often rely on the same communication methods and frequencies, they can easily interfere with each other if you are too close to another drone pilot or using a frequency range with limited channels. Standing far away from each other, making sure that there are no materials that can easily reflect the Wi-Fi signals, using a frequency range with a high number of channels and reducing interference from any other radio frequencies will ensure that your drone flight will be a safe one.