Emerging Anti-Drone Technologies and their Role in Reducing Security and Safety Threats
The drone industry is considered one of the fastest growing economic sectors in the world, and with the large increase in the number of these flying machines, which reached 2 million in 2022, serious threats appeared at the level of security and safety and the privacy of individuals through random uses and negative uses of them. The number of accidents reached 196 since 2017, of which 54 have caused disruptions to air traffic in 54 airports, which represents a threat to the security and safety of individuals and facilities and could be an obstacle for many countries to benefit from these technologies. One of the latest solutions adopted to meet this challenge is the Counter-UAV technology, which has witnessed rapid development, according to the latest statistics. According to the latest statistics, the anti-drone sector has reached $1.1 billion in 2021 and is expected to rise by 28% in 2030 according to the average annual growth rate CAGR.
It adopts different methods of monitoring and disposal. This paper explains the various techniques adopted with an indication of their efficacy and limitations.
In the last two decades Drones are becoming part of our daily lives, and it’s no longer a science fiction to see small machines flying over cities. In fact, the number of this flying objects is exponentially growing during the last five years, such in United States, according to the latest statistics made by the Federation of Aviation Administration [1] in 2022, In USA there are:
· 865,505 drones registered
· 314,689 commercial drones registered
· 538,172 recreational drones registered
· 280,418 Remote pilots certified
Globally, the total number of consumer drone shipments worldwide was around 5 million units in 2020. The number is expected to increase over the next decade, reaching 9.6 million consumer drone unit shipments globally by 2030. The consumer market for drones comprises recreational drone owners who fly for fun and capture photographs and videos during their flights[2] and according of that some undesirable impacts are taking place
The rapid increase in the number of drones flying over the skies globally represents an irreversible path in the UAVs industry, however there are several incidents that requires new solutions to avoid malicious uses and human errors and maintain safety and security in a high level.
In the other side of this development, we noted 196 serious incidents over the world caused by drones that threated the safety in airports, military zones, properties, prisons listed in the web site of AARONIA.
By analyzing this data in above, we can conclude that there is a serious threat to safety and security around the world especially when drones are sharing the airspace with civil airplanes, so it could threat lives, causes an air traffic disruption and holding for many hours. As a result of registered threats, the presence of a new solution against this challenge is an emergency, Although the presence of military solutions as counter-drone systems, most of them couldn’t be used in civil area, so in this paper we focus in civil C-UAV’s systems
Anti-drone technology, also known as counter drone, counter-UAS or C-UAS, counter-UAVs or C-UAVs refers to systems that are used to detection, classification and interception and/or neutralization of undesirable or dangerous unmanned aircraft systems during flight.
C-UAS is functioning based on detection of different features of drones such acoustic signal, Radio frequency signal RF, heat, visibility and physical shape (Radar
detection) which are detected using various types of sensors;
1 . Acoustic signal:
The noise emitted by drone motors and propellers is detected when the drone is flying, this system is a combination of an array of microphones which detects the sound made by a drone and calculates a direction. More sets of microphone arrays can be used for rough triangulation, this technology Detects all drones within the near-field, including those operating autonomously (without RF-emissions). Detects drones in the ground clutter where other technologies can struggle, the use range is maximum 500 meter and it struggle in noisy environment.
2. Radio frequency signal (RF):
Commercial drones use a radio frequency to connect between the pilot and the small aircraft usually 2.485GHz and 5.8 GHz, to receive instructions and send data
RFscanners can detect this signal and get various additional information about the control commands, the type, the position of the drone and the position of the
operator are detectable also but not all the time, because if the drones are controlled only by Pulse Position Modulation (PPM) or Pulse Width Modulation (PWM) messages, they may not emit location information on an RF channel. To ensure detecting this information multiple detector are needed and when receiving the RF signal from the same source they calculate the position[4].
3. Heat or Infra-red signal:
The hardware components (Motors, Batteries.) of the drone radiate a significant thermal energy during the flight which is detectable using thermal cameras [5]
The advantages of the thermal detection system are weather resilience, identification availability and lower cost compared with other systems, but the effective detection range remain short (50 meter).[6]
4. Radar detection (physical object):
The physical shape of flying objects is recognized by Radar which is an active sensor that continuously send waves and detect the reflected part to determine the shape of the target then the distance, the speed and the direction. Continuous-wave radar characteristically measures object velocity using Doppler information.
Frequency modulated continuous wave (FMCW) radar and coherent pulsed Doppler radar retain and track transmitted and received signal phases to estimate distance and velocity [6]
Radar surveillance and tracking uses several frequencies bands [7], [8], which we summarize below:
·
Ka, K, and Ku bands, above 18 GHz, very short wavelength. Used for early airborne radar systems, but uncommon today except maritime navigation radar systems.
· X-band, 8-12 GHz. Used
extensively for airborne systems for military reconnaissance and synthetic aperture radar.
· C-band, 4-8 GHz. Common in many airborne research systems (e.g. CCRS Convair-580 and NASA Air-SAR [10]) and spaceborne systems (e.g. ERS-1 and 2 and RADARSAT [11]).
· S-band, 2-4 GHz. Used for Russian ALMAZ satellites and weather radar.
· L-band, 1-2 GHz. Used for US SEASAT and Japanese JERS-1 satellites and NASA airborne systems.
· P-band, 300 kHz to 1 GHz. Longest radar wavelengths, used for NASA experimental airborne research systems.
Radar is also classified into 2D and 3D by the type of the phase array antenna [12]. 2D radars adopt passive electronically scanned array antennas (PESAs), which control beam steering by electric field phase applied to each array element, providing relatively large detection range while
wideband utilization is not possible. 3D radar commonly uses active electronically scanned array antennas (AESAs), which control beam steering and shape by the electric field gain and phase of each element. Although AESAs have relatively short detection range, they can self-correct errors and support wideband detection.
Several studies have implemented 3D radars, e.g. [13]. The main difference between 2D and 3D radar is that 3D radar can estimate the altitude of target
objects. whereas 2D radar acquires limited information of z-axis through auxiliary systems [14], [15]. 3D radar is desirable for anti-drone systems, but
2D radar with other methods can be a better solution from the view of large-scale monitoring and cost efficiency. Radar based drone detection offer
longer detection range and constant observability compared with RF scanner, but there are some detection availability and regulatory limitations. Radar cannot
distinguish a drone from obstacles if the drone hovers in one position or flies at low speed. Thus, combining radar and other technologies (camera, RF scanner,
etc.) is strongly recommended. Radar systems also continuously emit high power RF signals, so nation permission is required for frequency bands and
installation locations. In particular, facilities that already operate radars, such as airports [16] may have difficulty installing additional radars due to
RF interference issues. Partial spectral overlap between radar and radio waves can cause bad signal interference and poor performance of both radar and the
network. Several studies investigated mutual interference between radar from military or other government/private organizations and radio access networks such as 5G to ensure coexistence [17]-[24].
Administrator should consider these RF circumstances in anti-drone system installation.
5. Vision and Optical Camera detection:
Similar to thermal camera detection, optical cameras for drone detection have been widely investigated for anti-drone application. Sapkota et al. [25] exploited histogram of oriented gradients features to detect drones from captured images, and Jung et al. [26] proposed a video-based drone surveillance system to monitor large 3D spaces in real time.
Drone detection equipment based on optical cameras provide extremely low cost and less regulatory limitations than previously discussed ones, enabling fine-grained tracking system via dense deployment. However, the shortcomings including relatively short ranges, high weather dependency, and impermeability to obstacles force the fusion with different sensing systems. Widely adopted military electro-optical/intra-red (EO/IR) systems combine optical cameras and infrared sensors for drone detection [27].
6. Hybrid detection systems:
All anti-drone systems have some limitations (range, accuracy, interference…)
That’s why we recommend a hybrid detection system that combines two or more complementary
systems in order to improve efficiency
After the detection of a drone another must step is the identification of the detected object; the identity, the type, if it is legal or no, Drone detection refers to systems that observe a flying (or stationary) object and determine if the object is a drone, whereas drone identification refers to determining if the detected drone is illegal and hence should be neutralized. For example, a minimal radar system may barely accomplish drone detection, since it cannot distinguish between drones and similar sized birds without an additional prediction scheme or auxiliary equipment (e.g. vision/thermal cameras) [6]
The term Drone neutralization is used as a component of anti-drone system which refers to operations that suppress the threatening drones’ movements. We classify the neutralization methods as destructive and non-destructive. This classification is valid since it not only presents technical difficulty, but also availability within civil regulations. Destructing the illegal drones are currently prohibited in many countries, so non-destructive ways are preferred in several public constitutions. We address in more detail non-destructive methods, to achieve high utilization of anti-drone systems in the worst cases. Mostly, confirmatory methods such as jamming are preferred to prevent secondary crises (landing/crash and/or operational failure). Jamming is confirmatory and also nondestructive, but as discussed
above, causes temporary communication paralysis across the target area. Thus, recent approaches attempt to individually disturb the target drones,
considering their operation features
. The common Neutralization solutions are listed below:
Drone hijacking means that a defending operator stake control of the target drone regardless of the methodology
Drone spoofing means that the operator generates a fake signal to prevent the target drone from moving as intended by the original controller
Drone jamming focuses on paralyzing radio communication between the target drone and controller by strongly interfering RF signals, which can be any kind of empty packet signals within a targeted frequency range
We use the term killer drone to mean legal drones that track target drones and attempt to damage them [6]. To distinguish killer drone from drone capture, we limit the killer drone scope to solutions that physically strike invading drones. Killer drones require reactive and real-time decision making regarding incoming drones, high accuracy drone flying path estimation [28],
Geofence based drone neutralization systems prevents target drones from approaching a specific point, Geofence technology for drones is classified into two types [29]. Dynamic geofence propagates information regarding restricted flight zones, and static geofence uses a flight permission information repository that any drone can access. Most commercial drones with common flight control stacks, e.g., PX4 [30] and Ardu-Pilot [31], have internal auto-landing modules for safety. This method effectively prevents hobby drones from invading unlicensed areas, but cannot defend a modified or remodeled drone; disabling automatic landing systems built into the drone controller. Since the system relies on the drone’s internal navigation logic, malfunctioning drones may allow trespassing into the secured area. Further preemptive geofencing studies are required to address these limitations, which may utilize spoofing and hijacking techniques.
As discussed in this paper, there are several technologies related to the C-UAS systems which is in a dynamic state and keeps updating facing the continuous improvements in drone industry and that remains drone safety and security a challenging objective, so the standardization of systems between drone and anti-drone manufacturer is nowadays more than emergency to avoid malicious uses of this emerging technologies.
In addition of that Ant-drone technology represents a huge opportunity to searchers and developers and entrepreneurs, as it’s will be a continuous need if we consider the future of drone deployment especially when talking about taxi-drones which requires a very high level of safety and security
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