In part 3 of this series we discussed kinetic weapons, which physically interfere with a drone by striking or intercepting it, as countermeasures. Here, we’ll explore electronic countermeasures, or systems that interrupt the drone’s ability to navigate and/or the operator’s ability to control the drone.
Under current U.S. regulations, most of these systems are illegal for domestic use because they violate wiretapping laws, radio-spectrum protections, and illegal interference protections. However, these systems are being extensively tested by militaries all over the world, which speaks to their potential.
Today’s drones rely on three critical components to fly and execute a mission: a stabilization system, navigation system, and optical/command link with the drone operator. Stabilization systems allow the drone to orientate itself in the air. Essentially, knowing the difference between up/down, left/right, and inverted/upside down. The near totality of non-military stabilization systems can only maintain orientation without drifting for 30 seconds or so. After that, the drone loses its sense of where it is in space.
The Global Positioning System (GPS) is the satellite-based technology used by everything from our phones to cars to airplanes to build moving maps of our world. GPS can tell us where we are on the surface of the Earth and even our altitude. This GPS system also provides the spatial reference on which guidance and positioning information is used to fly the drone, thus making up for the 30-second drift stabilization problem above. This data, when combined with the stabilization system, allows a drone to accurately position itself in 3-dimensional space and fly a specific route between point A and point B.
Drones also carry cameras that provide visual data to the operator so that he can manually navigate the drone. That’s why you see drone operators wearing video goggles or having cameras on their controller.
Finally, there is a controller connecting the drone to the operator so that commands can be sent back and forth, and telemetry data can be received from the drone.
Systems that attempt to disrupt any of these three critical elements of a drone’s operation are considered electronic countermeasures. They fall into three general categories: jamming, spoofing, and hijacking. The first two attempt to prevent the drone from receiving data from either the GPS satellite constellation or the operator. While hacking attempts to replace commands sent to the drone by the malicious operator with those from a friendly operator.
Most people are familiar with jamming. This countermeasure uses electronic interference to block signals to the drone. Essentially, radio noise or nonsense signals are broadcast on the same frequency that contains either the GPS data stream or the command signals to/from the operator. Absent reliable signals, depending on the operator’s programming, the drone immediately lands itself. Alternatively, without reliable 3D position data, after about 30 seconds the drone will begin to stray and drift, perhaps being carried off by the wind or impacting an obstacle. In both cases, the drone cannot continue navigating.
Another form of jamming uses the same type radio interference to block the video signal to the operator, and the commands from the operator to the drone. If an operator can’t direct the drone and/or see what the drone is seeing, the device becomes useless. Jamming is not an all-or-nothing game--dropping a few frames on a video feed may be sufficient enough to degrade the accuracy of the navigation or, in the case of dropping objects, enough to make an operator miss his or her target.
Next we have spoofing. This countermeasure relies on replacing the local GPS signals that a drone receives with false ones. This momentarily confuses a drone, making it think it is off track and causing it makes corrections back to where it thinks it should be. In some cases, you could direct it to another city.
A simple way to think about this is by imagining you are in Chicago and then travel to Omaha with a GPS receiver and signal recorder. In Omaha, you begin to record GPS signals from the satellite. You then take this recording back to Chicago with you and begin to re-broadcast these recorded signals at a high-power setting.
Now imagine you are the drone flying happily along in Chicago. All of the sudden you start receiving GPS signals that tell you are over Omaha. However, you are programmed to be flying over Chicago. Yikes-- you now need to take corrective action to get you back on course. That starts a wild ride. There are other flavors of this type of spoofing, but all rely on making the drone think it is someplace where it not supposed to be.
Finally, there’s hacking. This countermeasure substitutes alternate guidance commands to the drone and effectively takes it over. This can be done through brute-force attacks where an amplified “friendly signal” overpowers the drone’s receiver and takes control, it can be done through code inserted into the command guidance data stream, or other techniques.
All of these examples relate to countermeasures designed to defeat drones that rely on external data for guidance, whether it is GPS or operator commands. That’s our ground truth today. However, autonomous drones that rely on internal sensors to sense their environment and guide themselves are being fielded today. In fact, AI is not required.
For these types of autonomous vehicles, we will need to have a different suite of countermeasures that include advanced materials, coatings, and deception. That’s what we will talk about in Part 5.