Ghoul Tool: The Weapon-Mountable Counter UAS Transmitter

May 1, 2023

As commercial drone technology continues to expand, small unmanned aircraft systems (sUAS) are making it increasingly difficult to secure battlefields and military installations. In response to these challenges, Trust Automation has developed an innovative counter sUAS system to disrupt and defeat hostile unmanned aircraft system (UAS) threats at the field level.

Called the Ghoul-Tool Attachable Transmitter (GAT), this compact, weapons-mountable system is the easiest way to field a jammer for UAS, providing command and control (C2), radio frequency (RF) and global positioning system (GPS) denial capabilities. Measuring just 6 inches long and 3.2 inches across and weighing less than a pound, it also supports mounting configurations on the side and bottom of small arms via a standard NATO accessory rail. A handheld grip also allows for standalone use.

Engineered by Invisible Interdiction and manufactured by Trust Automation, GAT is the result of significant research and development work done in collaboration with several groups within the U.S. Air Force, including the Air Force Research Lab (AFRL) and Hanscom Air Force Base. Over the last decade, we’ve seen the concept of counter UAS evolve from backpack solutions to handheld technologies. However, most handheld or portable counter UAS technologies require the warfighter to put their weapon down and then engage the drone separately on another device. Around 2018, the Air Force started seeking solutions to enable seamless transition between a warfighter’s use of counter UAS equipment and engaging a targeted drone with their primary weapon.

In 2019, GAT development began with the first phase of an Air Force Small Business Innovation Research (SBIR) contract to Invisible Interdiction to investigate how a small and powerful weapons-mountable counter UAS system could be developed. Based on their analysis, it was determined that RF jamming electronics could be embedded into a weapon-mountable device the size of a soda can. Once the Air Force saw that was possible and the system could be effective at that size, they very quickly pivoted right to the third phase of the SBIR contract that lead to the development of GAT prototypes as operational evaluation units. Since then, Trust Automation applied design for manufacturing principles to the design and progressed on through environmental testing, operational evaluation and now are in production with the Air Force for the GAT jammer.

Portable Field Use

Once operators identify and sight the UAS, they can engage GAT. The jammer’s energy is emitted as a focused cone of energy out the front of the system. At this point, operators can continue to track the UAS and engage the threat as appropriate.

GAT offers three types of jamming capabilities, covering all the bases for typical systems employed by commercial drone technologies.

First, GAT provides command and control (C2) denial for line of sight engagement. This effectively blinds the UAS from the operator’s controller. While the jamming response will vary depending on the commercial drone manufacturer, most aircraft will resort to a failsafe, such as pausing and returning home, or pausing and landing. These jamming effects may also be intermittent, depending on the presence of other RF signals in the environment — Wi-Fi, for example. Although C2 denial prevents commands from reaching the UAS, it does not block any broadcast messages.

GAT’s C2 signal jamming is a form of RF denial, a method that resembles a tug-of-war power battle between the jammer and UAS controller. For the jammer to be effective, its output RF energy must be greater or smarter than the output RF energy from the UAS controller. Increasing or decreasing the GAT operator’s distance from the UAS will increase or decrease the signal and jamming strength, turning this RF battle in one party’s favor.

As the ratio from user to UAS to jammer changes, the jamming effects may change. GAT was designed to provide an effective jamming range for all line-of-sight engagements.

Third, GAT is capable of GPS denial up to 250 meters. A drone’s GPS link is highly susceptible to jamming since it is a lower-power signal coming from a satellite. The effects of GPS denial will vary by drone manufacturer. This jamming method may prevent the aircraft from returning home or from executing a C2 failsafe. Some aircraft can become unstable and crash. In almost all cases, the UAS will not be able to continue navigating.

Power Management

Delivered in a single Pelican case, GAT comes with three jamming systems, two handheld grips, and a pressure switch. Leveraging advances in additive manufacturing to build powerful small and powerful electronics was a key factor in developing the weapon-mountable size of the GAT. The other key technology behind GAT is the use of integrated RF technology.

One of the main advantages of this implementation is its high level of integration, which results in smaller size, lighter weight, and lower power consumption compared to traditional discrete RF circuitry. The adoption of highly integrated RF circuitry has allowed the defense industry to generate complex waveforms with much smaller packages. The embedded circuitry featured on the GAT jammer permits its emitter, thermal management, operational indicators, control switches and rail grabber to all be assembled into a compact six-inch weapon-mountable device weighing less than a pound.

One of the biggest concerns with poorly designed counter UAS technologies is not only do they jam the drone, but they also knock out all of the surrounding communications. That can lead to the warfighter’s Bluetooth, GPS receivers and other RF communications they might be relying upon to shut down. RF jamming energy emitted from GAT is purposefully focused out the front end of the weapon and extending out in the direction the weapon is being pointed.

The focused energy extends out along the line of sight of the operator or warfighter and that is a result of the Invisible Interdiction team’s use of efficient amplifiers and diligent power management for GAT. RF devices also tend to generate significant localized heating which is a challenge to manage while maximizing the RF output energy. Diligent power management allows the GAT to generate a significant amount of RF power out in front of the weapon that it is mounted on. The power efficient design of the GAT jammer provides a standalone solution without the need for associated interconnections or backpack mounted power solutions.

GAT is an engineering milestone in arranging and assembling miniature-sized RF electronics. The Air Force allowed the Invisible Interdiction team to follow a development model, which allowed them to learn how to overcome the challenges of designing a weapon-mountable jammer with considerable C2 and RF-jamming capabilities. When Trust Automation implemented a manufacturing plan for the GAT jammer, only a few minor improvements such as a reduction in the number of fasteners was recommended prior to the start of full-scale production.

This article was written by Craig Vonilten, Vice President Business Development, Trust Automation. For more information, visit here  .

---