OverviewCountering enemy drones requires two tools: something to find them, and something to take them down. There are several commercial tools available, but the least expensive cost more than $10,000 each, and can only serve an area of one platoon, so this becomes very expensive very quickly. We’re working to greatly reduce that cost. As of summer 2022, we bought a few commercial jammers using donated funds, for the lucky cases when our soldiers spot enemy drones visually, which is difficult in wooded areas. We currently have nothing but their eyes and ears to find the drones, so our first task is low cost detection and tracking systems. Low cost jammers will come later, so we can equip more platoons with complete systems.
What are the threats in the field?The Russians are using two different classes of drones. The first is small quadcopters used mainly as eyes in the sky for artillery targeting. This includes commercial drones, mainly from DJI, and DIY drones. The second class is the Iranian fixed wing drones that made the news in October, essentially mini cruise missiles, which the Russians are using to destroy critical energy infrastructure in an attempt to commit genocide against Ukrainian civilians again, this time via winter freezing, instead of via starvation as in the Holodomor that the Russians perpetrated 90 years ago. The purpose of all this murder now is the same as it was then: punishment for seeking independence from Russia.
Which threat are we focusing on, and why?The Iranian drones are causing massively more death and destruction. However, we’re focusing on the quadcopters, for three reasons.
- Our engineering skills, available time, and financial resources are inadequate to defeat the Iranian drones.
- The Iranian drones received political attention, so state-level resources were allocated to solve the problem, including Israel’s Smart Shooter.
- Russia can continue raining Iranian terror from the sky for years, the same way Hamas does to Israel. Experience with the latter shows that merely defending against the attacks is futile. The evil must be rooted out at the source. In Ukraine’s case, this means forcing out the Russian military, which first requires defeating the Russian units on the front lines — which requires disabling the Russians’ eyes in the sky so that the Ukrainians can safely advance through artillery range.
What technologies can accomplish detection and tracking?The two classes of drones require different techniques.
Tracking Iranian mini cruise missilesThese weapons are fully autonomous after launch. They aren’t remote controlled. They also have no need to transmit information back to their operators, which means they can operate in radio silence. Therefore, passive RDF (radio direction finding) is impossible; they can only be tracked visually, thermally, acoustically, or by radar. We would love to produce automated tracking systems with those techniques, but we lack time and the engineering experience necessary, so we’re deferring those potential projects until later, to focus on passive RDF for quadcopters as our immediate task. And the mini cruise missiles might soon be thwarted anyway, if Smart Shooter is able to send enough systems, as explained above.
Tracking surveillance quadcoptersThese eyes in the sky broadcast real-time video feeds back to their operators, which enables their victims to detect and track them via passive RF monitoring. General techniques for such monitoring include:
- Directional antennas. Automated systems using this technique spin the antenna to scan the sky, and correlate received signal strength with the antenna’s angular position to determine direction to the target drone.
- Doppler shift. This is a spinning system with a non-directional antenna mounted at an offset from the center of spin. The received signal’s Doppler shift induced by the spin is correlated with the angular position to determine direction to the target drone.
- Phased arrays. This compares phases of the received signal at multiple antennas to determine direction to the target drone. This requires not only multiple antennas, but also multiple receivers, making this technique difficult to achieve at low cost.