How to tell if a drone is watching you at night

there are certainly some sinister reasons why people may want to be flying the drone at night. However, there are actually very few drones that can capture high resolution and identifying video or photographs from a relatively large distance at night time. This means that there are plenty of signs to work out if a drone is watching you at night. In this article, we will go over how to tell if a drone is watching you at night and give you all of the options for keeping you safe and secure.

You can tell if a drone is watching you at night by using the sound of the drone to locate its position in the sky. You can also spot it optically by using the lights on the drone. Alternatively, you may want to use a drone detection app to find out if there is a drone in your area.

The thing is that while drones are able to see very far into the distance the usefulness of the camera for identifying and spying on people depends heavily on the resolution of the camera. In my other article – how far can a drone camera see? – I give you a full rundown on exactly what drones are able to identify at various distances according to the camera that they are carrying. At night time, the amount of useful information that they can collect is severely restricted unless they are carrying a night vision camera. There are also some ways to add night vision to your drone which you can read about in my other article – click here.

If you are suspicious that there is a drone watching you at night time here are some of the important factors that you can use to determine if it is a risk to your personal safety or security.

1. Lights on drone

One of the first, and most useful, ways of determining if a drone is in the local area is to look into the sky for lights of a drone.

My DJI Mavic air has a light on the back of the drone and two lights on the front arms of the drone facing forward. These are primarily there to tell me what mode the drone is in and, I can turn them off.

However, it is important to note that if there are any drones flown by government agency or police officers they should fly with lights illuminated so that they are well within the regulations set out by the local authorities.

What color lights do drones have at night?

There is no set colour of lights that drones may have at night. For example, if it is a police drone it may have red and blue lights, and if it is a hobby drone it may also have a combination of LED colours.

Types of light on a drone

If the person is following all of the rules the pilot should have attached lights which means that they are able to detect the orientation of the drone at all times.

This means that you would need at least three lights on your drone to know both its location and orientation. A white light on top, a red navigation light on the left, and a green navigation light on the right – this is similar to what aircraft uses while flying at night too.

You can read more about the FAA’s rules here – click here.

By using these lights the pilot would be able to tell which way the drone is pointing and travelling. For example, if you can see a red navigation light on the right, and a green one on the left the drone is travelling towards you.

Not only must a drone pilot attach lights if they are flying at night, but they may also choose to attach spot lights to the arms of the drone during flight. You can add a lighting kit from a company such as LumeCube.

2. Drone detector app

There is a popular app called drone watcher.

The drone watcher app turns your android device into a detector of drones and is able to alert you and track their path. The app detects most commercially available consumer and prosumer drones and records the data including the drone type and ID which can be used to document evidence to be used by local law enforcement.

The developers of this app claim that the drone watcher app is able to detect, track, and records information on approximately 95% of commercially available drones using advanced signal intelligence technology.

The app alerts users when a drone is detected within half a mile recording the drone type and ID which can be used to document any complaints the person wishes to make against the drone pilot.

In additional to personal use for privacy protection the drone watcher app can also be used for drone control and security at public events.

If you are not sure if there is a drone in the area you can use this app to quickly determine if it is within half a mile of your current location.

3. Sound

There is no doubt that drones make a very specific and identifiable noise. This is dependent on the type of drone being flown. For example, my DJI Mavic air sounds like a swarm of bees whilst larger drones have more of a low hum quality to the sound of their flight.

The pitch of the same can be used to determine the size and type of the drone which is being flown and wants the drone passages about 60 m it is typically much harder to hear. That being said, at night time it is much quieter so you can typically hear a drone from further away.

Here is a link to a variety of different drone noise comparisons that exist on YouTube.

Drone noise comparisonLink
Mavic pro versus phantom 4 proYouTube
DJI inspire oneYouTube
Phantom 4YouTube
Mavic mini versus Mavic airYouTube
DJI spark, Mavic air, Mavic pro, Mavic pro platinum, Phantom 4 proYouTube

 

By using the videos in the above table you may be able to identify the type of drone being flown.

There are also other ways to distinguish between drone noises and other electronic noises in the environment.

Movement of the sound

Another very important identification tool for how to spot a drone at night is now fast the noise use through the sky. We are very familiar with how quickly a helicopter moves through the sky and its volume combined with its high altitude travel means that the sound doesn’t move location very fast. I.e., the noise stays around for a while.

Drones, on the other hand, change location very quickly and their relatively low altitude means that the sound is very different depending on if they are travelling away from you, toward you, or anything in between.

You can make a drone significantly quieter by using different propellers.

4. Thermal detection

If you have a thermal camera you are able to detect the hot electronics of a drone against the coldness of the night sky very easily.

As drones fly through the air their circuitry heats up relatively quickly. My DJI Mavic air is very warm when it lands and the battery is also significantly warmer. In order to recharge the battery safely I have to wait at least 30 minutes for the battery to cool down. The quick exchange of energy from the battery to the motors causes a relatively high amount of heat in the circuit boards which means that they are susceptible to being picked up on thermal cameras at night.

5. Radio Frequency detection

Drones can be detected by monitoring the radio frequencies that they use to communicate between the remote controller and the drone itself.

As you are flying a drone there is a continuous two-way data transmission between a drone and the pilot on the ground. The data is sent in various frequency bands which means that there is a lot of opportunity to detect the drone. One of the benefits is that there is no need for signal sending and it can be detected passively.

Drone Micro-Doppler

You can also detect a drone by monitoring the air currents that they produce. A micro-Doppler is able to detect the small air currents that are produced by the propeller. A study published in 2018 showed that you are able to use micro-Doppler measurements for detection and classification of small drones.

Micro-Doppler are Doppler shifts generated by the movement of the internal parts of the target drone. This particular movement is able to be used to distinguish drones from birds by extracting the unique radio identifier.

The scientists conclude that micro-Doppler radar has the potential for reliable small drone target detection and is also a promising candidate for being able to classify the type of drone as well.

Will a drone show up on radar?

It really depends on what is called the radar cross section of the drone. Essentially the larger the cross-sectional area the more likely it is to be picked up by radar technology.

There is a fair amount of interest in detecting drones for security and military operations. And the science is slowly building up ways to detect drones using different types of radar technology. For example, a publication from 2020 shows that you can use a special to the radar that uses a millimetre wave detection system to estimate the 3D position of the target drone stop the method was validated and it was shown to be effective in the field against two drones of different sizes that were purchased commercially and available to the general public.

Furthermore, a publication from 2018 showed that there are a range of different options such as ambient radio frequency signals, radar, acoustic sensors, computer vision techniques, and more for the detection of drones.

This is a rapidly developing area of science and we are learning more and more about how to detect drones easily and simply using radar, and other common technologies.

Who are flying their drone at night?

There are a range of reasons why people may want to fly their drones at night. There are plenty of opportunities for drones to capture incredible cityscapes and self-illuminated landscapes. However, it probably isn’t legal for hobby drone flyers to be flying at night.

In Australia, unless you have a specific qualification, you should land your drone at sunset. However, with extra training and certification, you can fly your drone at night.

These are the types of activities that occur at night with a drone:

  • police – the police use drones for surveilling and honing in on criminal activity. The police drones tend to be much heavier and may have up to 6 propellers. It is likely that the colours of the drone will be red and blue.
  • Security – private security firms can fly over their own property in order to monitor people that shouldn’t be on the property and locating assets to make sure that nothing has been stolen. Unless you are on someone else’s private property it is unlikely it is a security drone.
  • Scientists – if you live near a conservation park or wooded area scientists have been known to use drones equipped with thermal cameras for detecting wildlife at night. This could be what is happening if your local area is full of wildlife.
  • Perverts – we often think about drones being used by people to capture images without their permission. However, it is unlikely that a drone is able to capture identifiable features from a discernible distance at night.

What can drones see at night?

In my other article – How far can drone camera see? – I performed in-depth calculations on exactly what a drone can see and how far they are able to recognise people.

How far can drone cameras see?

Can drones take pictures at night?

In the security world, the most important factor is the number of pixels per foot at a given distance. This can be calculated from the resolution of the camera and the distance at which you are observing an object.

I calculated this for a night-time camera and this is what I found:

Pixels per foot for each camera resolution at various distances.

The most important aspects of this table are where the recognition, classification, and detection limits are. To understand exactly what a drone can see at these limits we must first understand what each means:

  • Recognition – this is the highest classification at which you are able to identify a person or object. This is 90 pixels per foot at night. You are able to directly identify features on a person such as facial features, logos, and you can also read license plates on cars.
  • Classification – at this distance you are unlikely to be able to identify a person but you can identify aspects such as gender, race or ethnicity, and can distinguish the make and model of the car.
  • Detection – detection is the lowest form of footage classification and even though you are not able to pick out details of a person or a car you are able to work out movement within the frame.

Given these limits, we can see that for a high definition (1080p) camera it is only able to recognise people from a distance of 5 foot. Past that it is quickly unable to classify or detect people with a pixels perfect of only 38 at a distance of 50 foot.

At 4K the detection distance extends to 100 foot and it is able to recognise the up to approximately 60 feet.

At this distance, you will certainly be aware of the drone in your local area and you may even be able to identify what type of drone is flying because it is so close.

This means that unless you are illuminating your own property or you have brought your own source of light it is unlikely a drone is able to identify anything about your person or property unless it gets very close to you.

This information is only useful if the camera drone is using a regular optical camera. Alternatively, the drone may be carrying a night vision camera but, in my experience, these are very uncommon and it is unlikely that the drone flying at night has this type of technology unless it is a military or police drone.

Summary

In this article, we have gone through all of the ways that you can tell if a drone is watching you at night. Luckily, there are plenty of ways of identifying whether or not a drone is watching you through the sound the drone makes, the lights that it has, you can use drone detection apps, or thermal and radio signals to determine if there is a drone in the local area.

However, we have seen that the drone is unable to collect identifiable information about you unless it is fitted with a night vision camera or has other high tech features which would only be available to very expensive drone models or military and police units.

The Author

Dr Andrew Stapleton is a writer and YouTuber with a PhD in science. He has written and/or produced videos for Science Alert, COSMOS magazine, and Australia's Science Channel among others. Andy started droneflyingpro.com to share his love and the research of all things drone! He has been a drone pilot for many years and has flown many types of drone. His favorite is still the DJI Mavic Air for the portability and functionality packed into a small and portable drone!