Indian Defence Review

Geofencing

Commercial UAV manufacturers can play a key role by implementing GNSS-enforced geofences within their system that prevent their UAVs from being flown within exclusion zones around airports, sports stadiums, government buildings, mil bases and other security-sensitive sites. For example, DJI, one of the biggest UAV manufacturers, has embedded geofencing software in its UAVs that prevents them from flying  over thousands of sites worldwide where UAV op is illegal. This would be an effective mitigation step for UAV intrusions from unsophisticated operators. However, sophisticated operators could hack the software to disable the geofencing.

Detection System

(a) RadarDetection System. Existing air surveillance radar system are ineffective against mini-UAVs as they are developed to detect large aerial platforms moving at high speeds. As mini-UAVs fly at similar speeds and alts to birds, the two could be indistinguishable from each other. For high-risk events and known appearances of high-risk personnel, it may be necessary to bring in radars that have the fidelity to detect such small objects, such as the Blighter system developed by Plextek, and operators trained to distinguish between birds and mini-UAVs. Further complicating matters, to avoid radar detection, mini-UAVs may be built using poorly-radar-reflective materials and fly below the alt of 100 ft.

(b) Acoustic Sensing Acoustic sensors op by identifying the distinct noise made by the motors that drive the propellers of UAVs. Drone-Shield’s acoustic sensor was designed to provide high detection rates with low false alarms. It contains a database of common UAV acoustic signatures so that false alarms are reduced (e.g., lawn mowers and leaf blowers) and in many cases the type of UAV is also included in the alert. This system is being used by law enforcement officers in the US to enforce “no UAV zones”. A significant advantage of acoustic sensing is that is that it has low cost, even when implemented as a network of sensing devices placed around the protection perimeter.

(c) Radio Frequency (RF) Emission Sensing. UAVs typically send data back to their controller through a wireless data link. Using a directional antenna or a network of synchronisedgroundstations, such RF emissions can be detected and located. In order to be economical and offer rapid detection, the system must have some knowledge of the emission centre frequency and bandwidth, which are regulated for commercial UAVs. Drone Labs’ DD610AR UAV detection system employs RF emission sensing of a UAV’s command and data links to identify the coordinates of the UAV and its operator, and the unique identifier of the UAV, which can be used to prove that a particular incursion was done using a specific UAV. However, RF emission sensing can be easily evaded by sophisticated operators by maint radio silence.

(d) Electro-Optical (EO) Sensing. EO sensors in the form of optical and thermal cams can be quite effective at detecting UAVs. Dedrone’s Drone Tracker, which combines optical and thermal cams, can be used to form an EO sensing network to incr the chances of detecting a UAV. However, optical cams would have a difficult time distinguishing birds from UAVs. By utilizing Cmptr algorithms that look at flight  patterns, it is expected that a bird will fly a more random pattern than a UAV would. However, this notion fails in a place where birds glide, such as seagulls, which ride wind currents and stay at a steady level, and this fools optical system. Furthermore, hobbyist UAVs are mostly made of plastic and use electric motors, and thus, do not produce a lot of heat. Thermal cams would more likely detect a bird a UAV in most cases.

Electronic Defence

(a)  Command Link Jamming and Appropriation. Modern commercial UAVs are control by one or more wireless links to the operator’s control equipment. Traditional radio control (RC) controllers are still used as a backup means of control even for UAVs capable of a high degree of autonomy. These controllers send low-level commands to the autopilot system, or directly to the UAV’s motors or servos that actuate the UAV’s control surfaces. Jamming a UAV’ command link could effectively eliminate the ability of the UAV operator to conduct accurate targeting within the denied area. Command link appropriation could be used to take control of a mini-UAV. However, to appropriate the command link, the defender would need first need to determine the communications protocol, channel (from a potentially largeNo. of channels and code being used. Furthermore, the command link could be encrypted.

(b)  Global Navigation Satellite System (GNSS) Jamming and Spoofing.Virtually all modern commercial UAVs capable of autonomous flight  are navigated using GNSS satellites. Civilian GNSS signals are weak, rendering them susceptible to jamming, and unencrypted and unauthenticated, rendering them susceptible to spoofing. The defender could take advantage of the weak security of GNSS to confuse or command the mini-UAV.GNSS jamming would force attackers to op either using line-of-sight (LOS) RC control, or non-GNSS autonomous navigation. LOS control exposes the operator to visual detection and recognition, and can be denied by command link jamming.

Kinetic Defefence

Commercial UAVs are in gen fragile in the face of hard-contact kinetic attacks, such as small guided missiles, cannon-fired smart munitions, lasers and firearms. However, in urban environments, where attacks are more likely, law enforcement and mil will be averse to shooting UAVs down because any project used may cause collateral damage when it returns to the ground.

Conclusion

The tools and tac used by the terrorist organisations in the twenty first century are showing signs of shifting focus from the predictable form of terrorism to a form where modern tech is being used intelligently. Infotech based tools and modern communicationsystem are being emp by terrorists to improvise the existing forms of threat. Terrorists are found using new tech to their advantage while involving themselves in maritime, aerial, cyberor few other forms of terrorism.

The present international system in a rapidly changing world order is characterised by multivalence, interdependence and political cooperation. In the present system, no particular country or forum can ensure global security alone. The structure of the international system is not only changing rapidly but the challenges are also evolving very fast. For a better world, it is essential to resort to a pluralistic security order based on a cooperative approach to security.

Till date the world has witnessed terrorists usingaerialform of terrorism with some success. At the same time, the counter terrorism mechanisms employed by states are found gaining success. Such measures appear to have deterred the terrorist groups and have also succeeded in averting some major  plans of the terrorist groups to cause damage. However, with easy availability of hardware required to build an UAV or a toy plane the possibility exists that the terrorist gps could opt for new techs to effectaerialterrorism. This is not to say that the terrorists would discontinue with the techs used all these years for action attacks such asaerialattacks which cause mass casualties.

Terrorist groups still resort to such terror means in future in order to produce destruction in the form of life and property of catastrophic magnitude and to send a political message. They could try to find the unconventional ways to defeat the counter terrorism apparatus devised by nation states in this regard. In view of this, it is essential to strengthen the intelligence gathering mechanisms. More importantly, there is a need to comprehend the likely possibility of attacks by using the mini-UAVs or toy planes in developing counter terrorism strategies.