Inside Unmanned Systems provides actionable business intelligence to decision-makers and influencers operating within the global UAS community. Features include analysis of key technologies, policy/regulatory developments and new product design.
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53 unmanned systems inside February/March 2017 the same time on the same frequency, but ema- nating from different angles of arrival. Given the wide range of frequencies over which potential threats can be expected, and the perimeter to be protected, the selection of a direction finding technology must also consider the ability of the system to geolocate threats that are occurring at the same time and on the same frequencies. It is important that behind the tech- nology of the system, these threats can be pre- sented to the user in a clear manner for them to be able to act upon the threat. Figure 5 gives an example of four drones being detected at the same time and the angle of arrival of each of the threats and the friendly police drone. Interoperability and Future-Proof RF detection systems play an essential part of a drone defense system; however, there are drone technologies that can operate based on a GNSS (Global Navigation Satellite Systems) waypoint system that do not emit an RF sig- nature. In this case, sole reliance on an RF detection system would be inadequate protec- tion for high-valued targets. The complete solution may need to incorpo- rate proximity radar technology, electro-opti- cal, or acoustical detection. Each of these tech- nologies can work in concert to complement the advantages and overcome the disadvantag- es of sole technologies reliance. Therefore, an open system interface that can enable any of these other technologies to "tip" the defensive system is important. Alarms or tipping of other systems should also consider visual, acoustic methods as well as text messaging (SMS) to predefined groups of mobile phones or as an XML message via an IP network. Further, the drone technologies are rapidly advancing. New RF interfaces continue to be incorporated into these commercial devices. It is important for the signal identification system to have a scalable approach to extend and incor- porate new RF signatures as they become avail- able. A database is only good against known threats. Continued vigilance against the new advances in RF interfaces is essential. Countermeasures Some of the countermeausures, such as drone catchers, laser weapons, and high- energy EMP (electromagnetic pulse) systems have been previously mentioned along with the unintended consequences these systems might have in certain environments. Some- times a countermeasure can be an increased vigilance or deployment of people to intercept the controller triggered by a system alarm or text message. The type of countermeasure to be used will vary depending on the circum- stances of the environment. RF countermeasures can be deployed where legally allowed. Effective jamming of the RC link may also have various consequences—for example, forcing it to the ground, reprogram- ing it to a fixed position, causing its controlled Figure 6: Low- power Follower Jammer technology can protect a range of about 2/3 of the monitoring perimeter.