Citadel Defense Company

Drone Defense System, Hunter algorithm, Titan
Type of C-UAS
Integrated systems

Detector, ECM.

The company was acquired by BlueHalo in November 2021.

Citadel Defense provides a comprehensive, automated system to detect and prevent s-UAS from entering a protected space. The system passively and simultaneously monitors multiple relevant frequency bands within the RF spectrum in search of emissions that correspond to the characteristics of drone control, video and telemetry signals. When a detected signal is determined to be valid, the system will utilizes multiple escalating tactics to prevent the drone/UAS from entering the protected area. Notification of detections, engagements, and system status is displayed via a dedicated tablet computer, providing the operator automatic or manual control of mitigation strategy. The system is rugged, compact, rapidly deployable (less than five minutes to set up), and can be seamlessly transferred between man-portable, vehicle mount, and static configurations. Citadel’s system has been fielded overseas, undergone combat evaluations and has third party validation.

Citadel’s technology is derived from expertise spanning several disciplines, beginning with detailed knowledge of the Radio Frequency (RF) control transmission standards used across all commercial (and most military) drones and UAVs. This includes the protocol variants utilized for Radio Control (RC), first-person video (FPV), and Wi-Fi-based control emitted by drones, controllers, and downlink transmitters. A single Citadel system can analyze and transmit signals spanning the RF range from DC to 6 GHz, including the 100 channels at 2.4 GHz and 150 at 5.8 GHz, the most commonly used bands for commercially available drones. The system is able to isolate and identify these signals from in-band RF spectral noise, discriminating a target signal from miles away. Once a potential detection is discovered it enters the machine learning-based signal path and is refined for detailed analysis and identification.

Proprietary algorithms then identify the control signal parameters, intelligently predict the rest of the pattern if necessary, and produce a transmitted mitigation solution. It does so via three approaches – Predictive, Targeted, and Smart Jam transmissions - based on control protocol and operator / mission preference.

Citadel’s algorithm has demonstrated an ability to detect and engage military and commercial drones not seen previously in multiple live demonstrations, and key to the Hunter Algorithm’s performance is the use of multiple classifiers. This fuses the capabilities of separate discrete machine learning algorithms to provide significant performance improvements and superior false positive rejection. The Citadel system will then either output a mitigation signal for the target drone system or issue a smart jamming signal localized to the control frequency/s identified.

Citadel’s technology is designed to comply with 18 USC 2511 (Electronic Communications Privacy Act) in relation to sampling radio frequency spectrum data and does not use packet headers to identify drone signals or any other identifier that could uniquely identify a specific drone or controller. Citadel assists with enforcing Temporary Flight Restrictions (TFRs), used by the FAA to restrict flights in certain areas. Some have become more permanent, like those around Disneyland, or are event based, such as when the President visits a location. The FAA publishes TFRs as necessary, but there are also unpublished TFRs for sporting events, wildfires and emergency situations outside of FAA publishing.

In March 2019 the company launched it Titan C-UAS system. “Designed and developed alongside U.S. warfighters and security experts, the Titan provides the user real-time information, identifying and classifying an approaching unmanned aerial vehicle or swarm, and selectively applying precise countermeasures to induce the UAV to land or return to its home base. Citadel Defense uses machine learning, artificial intelligence, and software defined hardware technology to rapidly address new threats – making sure the effectiveness of protecting people and assets is always ahead of the ever-evolving threat.”

In May 2020 Citadel released new software incorporating ‘deepfake neural networks’ to protect against adversarial attacks on protected airspace. The technology is designed to help US and allied forces combat growing enemy tactics that attempt to confuse existing security intelligence equipment as electronic warfare escalates. The company has incorporated ‘Generative Adversarial Networks’ into its Titan C-UAS solution.

In October 2021 The company has launched new solutions including Titan Drone Finder (DF), Titan Tactical Assault Kit (TAK), and Titan Multi-Sensor (MS) to address emerging requirements.


In March 2020 Liteye Systems announced a partnership with Citadel Defense to enhance their counter drone solutions.

In March 2021 Citadel Defense teamed with Syzygy Integration to develop a custom counter drone application for the Department of Defense (DoD) and federal government agencies. The application accelerates situational awareness and co-ordinated responses to uncooperative drone activity around critical infrastructure, National Special Security Events (NSSE), military bases, and the border

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