CRFS‘ advanced spectrum monitoring solutions enabled a client operator to transform its ISR missions at sea and across hostile borders. The mission was achieved through the use of an integrated combination of ground- and air-based RF sensing solutions. Operating in vast and contested environments where traditional monitoring methods fall short, the client leveraged CRFS’ technology to achieve enhanced situational awareness, improved target acquisition, and reliable detection of electromagnetic activity across complex operational theatres.
Problem: Protecting large geographical areas from hostile threats
Governments conduct ISR missions to maintain situational awareness, often over vast international and maritime areas where data collection is challenging. Spectrum monitoring is a key part of ISR, enabling forces to identify who is using the electromagnetic spectrum, what they are transmitting, and where they are located. Traditional ground- or sea-based monitoring is limited by geography and the radio horizon. Deploying RF sensors on airborne platforms significantly expands coverage and detection capability. Recognizing this advantage, a Ministry of Defence partnered with a drone manufacturer and CRFS to integrate airborne RF sensors, overcoming coverage limitations—particularly in large naval operational environments with limited assets.
Solution: Ground & air sensors working together
The client operator deployed a number of RFeye assets, including the Direction Finder (DF) Arrays, at appropriate locations on high ground. DF Arrays are high-performance, fixed-site systems designed for spectrum monitoring and locating radio frequency (RF) signals using angle of arrival (AoA) techniques. They use multiple antennas and advanced signal processing techniques to precisely locate the direction of a signal, even in complex and noisy environments.
The airborne deployment required innovation and integration work. Existing MALE (mid-altitude, long endurance) drones were fitted with RFeye Nodes as an ISR payload. When fitting a drone payload, many critical considerations typically challenge the integrator: size, weight, power, environmental operating range, and backhaul data rates.
The RFeye Node was an ideal choice. Small and weighing approximately 3kg, the RFeye Node requires very modest powering and does not negatively affect the drone’s operational endurance. It is capable of withstanding extreme environments, happily operating at the freezing temperatures experienced at 3000 feet (1000 meters) with no performance degradation.
RFeye Nodes operate in narrow backhaul environments. The unit is a complete RF front-end, and processing is performed on-board. Therefore, the data connection is extremely ‘thin,’ maximizing the available bandwidth to deliver required data in real time.
Results
The military operator increased its spectrum coverage range by combining fixed land-based RFeye Arrays and flexible air-based RF Nodes. Multiple sensors allowed the military operator first to build a detailed picture using ground-based assets before sending RFeye Nodes to 3000 feet, operating many hundreds of kilometers, increasing both the signal horizon and line of sight.
The combined mix of ground-based DF and air-based RF sensors enabled both AoA and TDoA geolocation of a range of signal types, meaning the operator can now perform ISR missions over a wide area (thousands of kilometers). Last, as the process is passive surveillance, any hostile forces operating in that area remain completely unaware.
The military end-user took its operation capability from being clever to supremely intelligent.
Equipments Used