Inside Unmanned Systems

FEB-MAR 2017

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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54 unmanned systems inside   February/March 2017 landing or eventually leading to the activa- tion of a return-to-home mode. The key pur- pose of RF jamming is to create interruption or at least strong interference of the targeted RC link to disable the threat's communica- tions and disrupt any further hostile actions. "Barrage jamming" is a process of generat- ing a high-powered RF signal to eliminate all communications channels at a particular fre- quency band. This could have an unintended consequence of also disabling "white listed" as- sets and other communication technology in the spectrum. A more effective "follower jam- mer" technique needs much lower power than required by a wideband barrage jammer. With this low power approach, jamming is possible from about 2/3 distance to the remote control under line-of-site conditions. Figure 6 shows the representation of signal detection perim- eter vs. the signal protection perimeter for a follower jammer technique. The key to success of RC jamming of a drone is to equip a system with prior comprehensive knowledge of the RF signal identif ication parameters. When an RF countermeasure jamming system is incorporated into the RF detection system, the list of RC links (FHSS) with potential threats are known to the user of the jamming system including their modula- tion parameters (e.g. hop set/frequencies, tim- ing, hop rate, channel bandwidth, modulation type, symbol rate). The follower jammer can be tailored and targeted toward countering a specific blacklisted drone at the point of each of the RF hops contained in the RC signature information at the specific time of the RF channel occupancy. Instead of a barrage jamming, which needs much higher transmitting power and does not discriminate any friendly signals, the follower jamming technology enables each single burst of the RC signal to be jammed but not the other legal signals. This allows the jamming of the targeted RC with almost no disturbance of other communication signals within the same frequency band (e.g. WLAN/ WiFi communications). Timing is a very criti- cal criterion in drone jamming. Once the tar- geted RC link is detected, the jammer exciter response has to be fast enough to hit the hop while it is still on air. The jamming solution must be able to detect and respond to a single active burst. Once the next hop is active, the system must detect it immediately and re- spond to it accordingly. Follower jammer technology can be a very effective compromise to a high-powered bar- rage jamming solution, and depending upon the fail-safe mode of the drone, this interrup- tion of signal can be difficult for the RC user to detect anything is wrong, enabling crucial time to deploy other assets to the location of the remote control user Preserving the Evidence After an event, one may need to provide evi- dence for legal assessment. Data recording and automatic event logging that begin with the Figure 7: Rohde & Schwarz's R&S ® ARDRONIS radio monitoring solution combines detection, identification and threat mitigation in a single, portable, highly reliable system. ENGINEERING » DRONE TECHNOLOGY sponsored by ROHDE & SCHWARZ

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