Unmanned aircrafts and security problems
Unmanned aircrafts – also known as Unmanned aerial vehicles (UAVs) or Drones, are self-contained flying vehicles that does not require the operator on board. At the beginning, UAVs were used in military only. However, due to the wave of Industry 4.0, they were widely used for nonmilitary purposes, especially in the fields of broadcasting, geography, technical space. The drone market has thus become a potential market with a rapid development, leading to the widespread of commercial drones.
Undeniably, the existence of unmanned aerial vehicles has created a completely new way of approaching – monitoring – gathering information with such advantages as: low cost, easy to operate in complex terrain and dangerous areas, useful in emergency situations… However, the spontaneous use of drones as well as the lack of strict management over the ownership of this equipment will potentially pose unpredictable risks affecting social order and national security.
In such narrow space as residential areas, there is the posibility of collision between drones and people, vehicles, or power lines. Also, flycam has been known as the privacy nightmare since they were sometimes abused to spy on technology and sneak. Even more concerning, as the takeoff weight of one UAV is up to kilograms, drones are used as a new medium for smuggling to transport contraband. The worst scenario is drones in hand of terrorists. They ultilize drones to penetrate government facilities and military zones; conduct terrorism (dropping bombs, chemical agents or biological agents …), disturb crowds, or spread leaflets to fight against the government.
Therefore, in addition to fastening the legal corridor over the ownership of UAVs, investigating on technical solutions is a necessary and urgent countermeasure in Vietnam and all around the world.
Drone Detection Technologies
In fact, the threat must be detected before it can be mitigated. The very first drone detection were conducted by optical and audio methods. People simply used cameras, binoculars, heat sensors or ultra-sensitive directional microphones to detect the sound or radiation from drone motor. However, these methods are strongly affected by the environment and weather conditions which leads to a high error rate.
Since then, low-level radar was used to detect target unmanned aircrafts. Radar operates at ultra-high frequency radio frequency, emitting into space a pulse of ultra-short wavelength. During the propagation process, the radar wave meets any target, it will be reflected. Velocity and reflecting time of the wave help to determine the position and direction of the UAVs with high accuracy. However, the efficiency of this method is limited in the inner city due to complex structure. Therefore, manufacturers have studied new detection methods based on operating principle of unmanned aircraft.
Unmanned aircrafts are usually operated in two ways: (1) automatically follow the pre-set route based on GPS coordinates. (2) fly under real time orders from the ground control unit via radio transmission. To some extend, no matter how drone is operated, there is always the presence of data link or control link. This is the key point for researchers to develop an effective detection system based on radio frequency (RF) method. RF detection system uses high-sensitive RF/Spectrum Analyzer to collect signals transmitted from/to the drone. This type of detection is able to detect targets at long distances with high accuracy; less dependent surrounding environment, suitable to deploy in many terrains.
There are 03 ways to handle with unmanned aircrafts once they are detected: Destroying – Hijacking – Jamming
Hijacking or spoofing seems like the best solution to counter illegal entering of drones. This method interferes with the control frequency range of drones by decoding and intercepting the control protocol to take over the control of the targets. Nevetheless, this method is almost theoretical because nearly no manufacture is able to decoding patented the protocol from a wide range of drone manufactures.
Meanwhile, destroying drone is considered the most rudimentary solution among the mentioned. In this method, security forces use laser guns, missiles, birds or drones to shoot down or attack the target drones. However, this measure is quite costly, passive and does not solve the root problem in case the drone is being used for disturbance, terrorism or spreading wrong information.
Therefore, jamming has been considered to be the most safe, simple and effective solution which has been deployed in many countries. To do so, people use RF systems to keep track of drone targets. After that, they use a RF gun or directional antenna system to emit a high-powered RF beam with appropriate frequency towards the target drone with a view to disturb the control link. Without control signals, drones will return the starting position or vertically land on the ground .
Each of the above detection and processing methods has its own advantages and disadvantages. In order to improve protection efficiency against the attack of unmanned aircrafts, it is necessary to have clever combination of different methods.