This post is a quick recap of Global Drone Security Network (GDSN) #3.
We are honoured to host presentation from Antoine Menini from CERBAIR. If you haven't watched his talk "UAV Miniaturization and Countering Drones: How RF will Always be the Right Choice vs Radar" please visit our YouTube channel.
UAV Miniaturization and Countering Drones: How RF will Always be the Right Choice vs Radar
Thank you very much, Mike. So, everyone, my name is Antoine Menini. And I'm the CTO of CERBAIR. CERBAIR is a French company that is specialized in providing Counter Drone system. The company was created in 2015. We develop, manufacture and sell our own Counter Drone solution based on radio frequency detection, and we work with major French and international government institutions. Today, I'm going to talk to you about the miniaturization of drones and its impact on radar versus RF detection. We are going to debunk some common myths about drone detection and I try to show you why RF detection still remains a good choice when it comes to detecting drones.
Oh, sorry. So first, let's look at the biggest drone manufacturer in the world, which is DJI. You will see in this slide the evolution of their consumer drones from the first DJI Phantom that was in 2013 to the latest DJI Mavic mini two that was released just last year. Also, it was a best seller, DJI has now abandoned the Phantom series to focus on the Mavic series, whose drones are way smaller and easier to carry around than the Phantom ones. You see, for instance, the DJI Phantom. The first one, weighed 1200 grams, while the weight of the latest Mavic mini two is only 249 grams. And we see the same patterns with other big drone manufacturers such as Parrot with the ANAFI drone, for instance, which is also a very small drone. And we try to have a look now at what makes the evolution possible. So drones are becoming more and more intelligent with more sensors, more features, better cameras, and at the same time, becoming smaller. So this change is mostly driven by the by the smartphone industry, the race to better smartphone cameras and more processing powers allows a lot of electronic manufacturers to get better components tha tare the same time, also cheaper. Let's take let's take for example the ARM CPU architecture. If you have a smartphone, most likely, you will use this kind of processor rather than the x86 Intel architecture used by a computer. The advantages of this architecture is that it consumes less power, therefore produces less heat, while at the same time being small in size. Apple has even decided to make a computer with this exact architecture. This is the apple M1,which is using the latest MacBook. So the ARM architecture is really great for low power consumption and this improvement in local CPU are now being used drones to allow them to have more processing power. Cameras have also improved a lot in in the last year. So you might have noticed that current generation of smartphones, now have two, three more cameras that have high resolution. And the same sensors that are used in smartphones can be used in drones to get awesome pictures. If we compare for instance, the size of the camera of a DJI Phantom with the latest cameras of the Mavic, we see that the size has decreased a lot and at the same time the resolution and the quality has increased. So these major pushes on the smartphone industry also benefits the drone industry. Batteries represents almost a third of a drone's weight, battery technology has also faced a strong evolution. First, also because of the smartphone industry now the batteries on the smartphone are getting better and better every year. But also more recently, thanks to the research on electric vehicles and electric cars. This means that nowadays, the battery can deliver the same amount of energy and are lighter than before, which lead to smaller motors and drones, smaller propellers and in the end, increased autonomy. So some studies suggest that the battery energy density, so this is the ratio of energy per unit of weight in a battery has tripled since 2010.This means that, we are now able to put three times more energy in the same battery than we were able to 10 years ago. And the drones that we see now, the DJI Mavic Air, for instance, were technologically not able to exist 10 years ago. The way we use drones, has also changed a lot. So 10 years ago, drone couldn't do a lot except for maybe flying a little bit not far away, and not very long range. The battery didn't last as long as today. And flying a drone was more than a hobby.
Most of us remember the first drones that were really big and that you had to carry around a big backpack. This has changed a lot. Now, drones are smaller, more affordable and capable of a lot of things. And people view them more like a tool to take great pictures of video while doing other stuff. For instance, now when you are doing sports, like skiing or running, the drones are automatically able to follow you outdoors and take great pictures of you. So there are now viewed as a companion in leisure rather than leisure themselves. And therefore, they have to be able to be packed in a suitcase very easily. This was not the case in the in the first generation of drones. Regulation is also a major incentive for drone manufacturers to come up with drones that are under some weight limits so that users of drones will get less restrictions. Good example of this is the new drone regulation that was just passed in the European Union. As you see, in the table, the regulation organizes drones in two different categories, C0. C1, C2, C3. And these categories are based on their weight. So you see that the law is not the same for all types of drones. And drones under 250 grams require no training at all and can even be exempt for registration if they are considered as a toy. So I'm sure that now, you might probably understand why the new Mavic Mini to weighs exactly 249 grams. So that users are able to use it almost freely without being able to have any regulation difficulties. So all of this pushes for drones that are smaller. But now let's have a look at the consequences on radar detection that monitor drones. So first of all, what is radar detection and how does radar work. Radar is a tool that detects physical objects. Basically, what it does is that it sends an electromagnetic wave at a very specific frequency. This wave is then reflected on the object. This is called the echo. And the echo is used to determine the direction and the distance after reflecting objects. If the object is moving, the frequency will slightly shift on the echo and this is called the Doppler effect. So we can use this effect to get the speeds of the object relative to the radar. Radar is a great technology that has been used since World War Two as a primary way to detect airplanes all around the world. So it's really a great tool, but it's kind of difficult to use in drone detection. So the first problem with radar when dealing with drones is range. In order to be able to properly analyze the return signal, this signal, of course has to be strong enough. The proportion of the reflected signal on an object is called the radar cross section, or the RCS. Radar cross section depends on many, many factors. First of all, for instance, the material of which the target is made, the size of the target relative to the wavelength of the radio signals, so this is the frequency. But one of the most important is the size of the target. And so as drones are becoming smaller and smaller, they are made out of plastics, then their RCS, the radar cross section of the drones, is also becoming smaller and it's really difficult to detect them at long range. So we need more and more powerful radars to detect the these types of drones. Radar also will detect everything as we see when we send a wave, the wave is reflected and everything will reflect a wave. So we need a treatment we need to apply a treatment to eliminate what is called the ground clutter. Clutter, basically, is the reflection on everything with the radar, so the wave will be reflected by the ground, by buildings, by trees, by almost anything. So the first process that's being used is called moving target indication or MTI. This process is based on the speed of the object that is detected. And we want to eliminate stationary objects to be able to filter out the clutter. The problem with drones compared to airplanes for instance, is that they can move very slowly, or they can even stay stationary. So, it's very difficult to find a good threshold. If the threshold for instance is too low, you will detect everything, you will detect their ground, you will detect the buildings, will detect everything, but if the threshold is too high, you will not detect drones that are moving slowly or that are stationary. So engineers have come up with new solutions to face this issue. So, also, the process isn't perfect, because there are also moving objects that we want to eliminate like branches or trees or people walking or cars. So, engineers have come up with anew solution and a new way of discriminating targets. This way is called a stationary target indication or STI. Here the idea is to exploit some intrinsic characteristic of the moving object like for instance different size, which is relatively small compared to ground clutter. So for instance, the building will reflect a lot of energy whereas drones or smaller objects like that will reflect smaller energy will be at a different distance. So this is used a lotto do discrimination of targets. But the problem is that there are also targets that we would like to discriminate like birds, for instance, birds cause a lot of problems with radars, because their size is approximately the same as drones. And so, the radar cross section of birds is approximately the same. Birds, as you know, are made mostly out of water and water reflects radar signals a lot. So, we need a way to discriminate birds against drones. So, most of the times this way is the micro Doppler effect. So we already saw in the previous slide, the Doppler effect which shifts the frequency of the return signal if detected object is moving. So now if the detected object or any structure on the detected object, has mechanical vibration or rotation, it will induce a frequency modulation on the return signal, this frequency modulation can be detected. And this way we can we can see what type of object we are detecting. And so this is typically the case of the drone propellers which are rotating when the drone is flying. And this is a great way to discriminate drones against birds. Because they have different micro Doppler signature. However, you have to understand that these effects strongly depends on the size of the moving object, and of the material of which are made. So drones are becoming smaller, so their propellers are becoming smaller. So it's becoming more and more difficult to detect them using micro Doppler effect, because the propellers are now made out of plastic and not made out of metal anymore. And the effect of the micro damper is also stronger on quadcopters than on fixed wing drones, because fixed wings, drones have generally only one propeller. And finally, it's important to understand that the detection of the micro Doppler effect is only possible at a distance, range shorter than the standard detection distance. So if the range of the realize gets lower then the range of the macro protection gets also lower, for instance. So if we take quadcopter drones and radar that has a detection range of about one kilometer for instance, then the range at which we will be able to detect the micro Doppler effect will be something like 500 meters. So as drones are becoming smaller and smaller, it's really difficult for radars to to be able to detect them because of the physics of the radars and of the physics of the waves. So in conclusion, we see that drones are getting smaller thanks to new available technology, mostly available technology made of consumer smartphone markets. But obviously, the strength has also some limits. So for instance, smaller drones will have more difficulties to fly during high winds and so the smallest of the drones, you see sometimes metal nano drones that are like 10 centimeters wide. These nano drones are really difficult to fly outside because of the wind. Also, in order to be effective, the communication antennas of the drone need to have a certain size. So typically, for instance, at 2.4gigahertz, the typical size of an antenna to watch properly, it's six centimeter. So if you want to lower the size of the drone will need at some point to decrease the size of the antenna. And this will not be great for propagation. Also, batteries are getting more effective. But as we saw battery only represent a certain percentage of the drone total weight, we see that we saw that on DJI drones battery represent approximately a third of the total weight. So even if battery technology will most likely continue to improve in the future thanks to smartphones, thanks to electric cars. We still need other parts on the drone, we still need motors, will still need propellers and other components that are more difficult to miniaturize. So that means that the effect to the miniaturize drones also have some physical limits. But as a matter of fact, they are becoming, they still continue to become smaller and smaller. And it's more difficult for radar to detect them at reasonable range because, again, of the physics. For instance, you can see this nano military drone on the right of the screen. This drone is called the Black Hornet. So even if the flight capabilities are not the same, of course as the one of the bigger drones, this drone is also almost impossible to detect using radar technology. So this is where also complimentary technology can be used to detect drone and one of them is passive RF technology. So let's have a look at what passive RF technology is. Most of the time when you use the drone, there is a bi directional communication between the drone and the pilot in order to fulfil the mission. So the payload with the remote control will send commands to the drone, and the drone will send back telemetry data. So real time position, speed, sensor, status. But most importantly, the drone will also send a real time video link, we the pilot, most of the time is able to see in real time, what the drone is doing, what the drone is filming.
So the principle of passive RF system is to detect these two way communication. Most of the time, this kind of system relies on drone signals that are based and is able to take both the drone and the pilot. So one of the great thing about this type of system it does is that it does not depend at all on the fixed physical size of the drone. A nano drone, a small drone can be detected as easily as a big drone that is 10 meters wide. Provided of course, that the signal power is the same on both drones. Also, contrary to radars, it does not need any direction line of sight, any direct line of sight between the drone and the detector. So RF detection is a great technology that is very complimentary to radars. But many people are argue today with the state of technology and artificial intelligence, we can have drones that are fully autonomous and that have no detailing at all. Drones can be programmed using GPS waypoints, or even image recognition algorithms to perform their mission result without being controlled from the room. So for such drones, of course, passive RF detection is simply not possible as it relies on radio frequency communication between the drone and the pilot. So if there is no communication, if there is no radio frequency whatsoever, we cannot detect it, of course. So such technology exists a little bit. But we'll see that it's far from perfect, does not work like magic. And also it's operationally quite difficult to use. So we'll see, we'll see some examples of this. So why is it difficult to have drones that are fully autonomous, is because communication when using drones is essential. So communication takes a vital part. In the drone's missions, whether they are civilian, military, benevolent drone, malicious drones, communication is really important. So let's imagine for instance, that you have a reconnaissance mission, and you want to explore the site to obtain some information about enemy presence, activity. Of course, it's a good idea to send a drone, because you will reduce risk on the operators, you send a drone first, and then maybe you do something else. The thing is that you don't necessarily know in advance what you will look for and where you will need to look. You can imagine, of course, filming with a drone without any transmission. So you stored the data on the drone, the drone performs its pre-programmed mission. And then when the drone comes back, you can retrieve the data and see everything that the drone has filmed. But what it means is that the information that we'll get from this could be outdated. During the 10 minutes of the mission, things could change, people can move. And also, you risk losing the drone. Because if you lose the drone, if the drone is struck, if the drone has a technical problem or anything, you will get no information at all from this. So we see that live information for reconnaissance is really key. That's why most of the time even if the drone is pre-programmed, your operators want to get the live video of the drone to be able to to see what's important and to be able to change the mission. So we mentioned now that you want to use a drone to destroy target, for instance. So drones are used a lot for target designation because they are quite precise. And also because we reduce risk as well for the operators, but drones are also used directly as a means of attack. Obviously, you can program a drone. Obviously, you can program a drone using GPS waypoints. And you can program it to attack a precise position based on the geographical coordinates of the of the position. But there are some drawbacks that you must take into account. So first of all, the position of the drone, using GPS will most probably be inaccurate by a few meters. It's not a lot because GPS signal is quite accurate, but this could cause you to miss the target. Especially considering that most of the time, drone payloads are limited. So precision in hitting the target is key. So, programmed drones are not very good tools to attack targets. Second, if you do this, you will rely solely on Genesis satellite signals. And this Genesis satellite signal can be spoofed or jammed. And this could destroy the mission. Also, the target has to be stationary. So you cannot use GPS, GPS waypoints to attack a convoy to attack a moving person. So we see here that with these two small examples, even if technologically, we can program a drone to perform some missions, operationally, it's a little bit more difficult than that. It's not as easy as just pressing two buttons, saying okay, I select this target, attack this target. Unfortunately, communication between the drone and the operator is still essential. Then we'll see that identification is also essential. So you might know that drone regulation all around the world is pushing for drone remote identification. So if I take the example of France, for instance, that I know quite well, France passed a law that required drones over 800 grams to constantly send in the air their identification number, as well as the last position. The EU and the US are working on quite a similar regulation. And this will allow authorities to control to control drones way more easily. But this type of system is also very important for military drones. Even if the purpose for military drones is a little bit different. It's very important, operationally speaking to be able to recognize your own drones when you are flying them to avoid unintentional friendly fire. For a long time, as you might know our planes have been equipped with IFF system, identification friends or foe, which uses radio transponder to identify the broadcaster. This is really important, because as more and more airplanes are flying, if you don't have a clear situation, especially during war, you can have issues. In 2003,for example, during the second gulf war in Iraq, a British tornado was shot by American Patriot missile. So friendly shot because of technical deficiencies with the IFF system. So we see that it's very important to be able to communicate with your drone, but also to be able to identify your drones. So as a conclusion, there are, of course, a lot of trends in artificial intelligence and autonomy. We see it for autonomous vehicle. And we see it of course, with drones. But we see that drones rely a lot on communication to perform the mission. So most probably, that we continue to use RF data link and to be detectable by passive RF system. At the same time, the technology allows for these drones to be smaller and smaller, while performing the same mission. Soof course, radar technology is great and will continue to stay a primary way to detect moving objects like drones. But we see that there are some drawbacks and that radars face a lot of difficulties when dealing with drones, especially if the drones are smaller and smaller. Sure, it's a little bit easier to detect a big Reaper, big military drone using radar, but for nano drones as the one that that we have seen before, it's much more difficult. And this is where passive RF technology, I think will always be a great complimentary choice. And, of course, the best solution is the two of them working together. So this is the end of my presentation. Thank you very much for listening to me, and I'm happy to answer any question that you might have on the internet.