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Stopping a drone from flying is not a trivial task and no single solution is a panacea. Visual and sound detection can be subject to impaired performance and errors from environmental interference. Radars may not detect drones with a small form factor and Electro/Optical (EO) sensors may not work in adverse weather conditions such as rain or fog. Even RF detection would not be effective alone on a pre-programmed drone using GPS waypoints for guidance. The presence of a radio link is necessary for RF detection. However, a RF detection system is a key trigger point for most of the consumer drone technologies in use and has a distinct advantage of speed of detection versus other technologies.
To be effective, RF detection systems must provide a high level of sensitivity, give an early warning and not create false alarms. A complete countermeasure system also requires a safe, reliable means of stopping the threat. An RF detection system can be a useful part of the complete workflow for a system that includes other sensor technologies.
One of the critical shortcomings of protection systems has been the integrated workflow between the detection system and the immediate interaction between the detection and countermeasures systems to attain a high level of success.
Figure 1 gives a workflow for consideration and forms the framework for the design challenges of detecting possible threats from drones. In this article, we will focus on the detection and location drones controlled by RF links, and the need for interoperability and customization as technology advances.
Situational Awareness: Detection, Classification and Geolocation
While no universal standard exists for the remote control of drones, the majority of drone technologies are radio controlled and emit an uplink (controller to device) and downlink telemetry or video signal back to the user. The RF detection system has a distinct advantage for the detection of a radio controlled drone-time!
The RF link establishment between the controller and the drone gives the RF detection system a substantial advantage in assessing the threat situation.
While most operate in the unlicensed ISM bands at 2.4 or 5.8 GHz, other frequency bands are also used including 433 MHz and 4.3 GHz. Some of the older frequencies used by radio controlled devices include 27, 35, 40.68...