History

More than twenty years of research in radar, navigation and localization

The Radar and Navigation Group at the University of Rome Tor Vergata has been active for more than twenty years, developing research at the intersection of radar systems, signal processing, localization, air traffic surveillance and satellite navigation. From its early work on high-resolution airport radar and surveillance systems, the Group has progressively expanded its activities toward multilateration, GNSS, resilient navigation, cybersecurity and, more recently, navigation beyond Earth.

The Group’s research has always combined theoretical analysis, algorithm development, system design and experimental validation, with a strong emphasis on real-world data and collaboration with universities, research institutions and industrial partners.

From radar processing to airport surveillance

The origins of the Group’s research activity are closely connected with radar systems and air traffic surveillance. Early research focused on high-resolution radar for airport surface surveillance, including signal processing, detection, CFAR techniques, plot extraction and target tracking.

These activities contributed to the development of advanced Airport Surface Movement Guidance and Control Systems (A-SMGCS) and included experimental validation using recorded radar data. Research in this period addressed challenging problems such as target detection in complex airport environments, multipath effects, target heading estimation and the processing of high-resolution radar measurements. Publications from the mid-2000s document this transition from radar theory and algorithms toward complete surveillance processing chains.

Multilateration and Mode-S surveillance

A major research direction subsequently emerged around secondary surveillance radar, Mode-S and multilateration (MLAT).

The Group developed algorithms for time-of-arrival estimation and target localization, investigated the fundamental accuracy limits of distributed sensor networks, and studied efficient techniques for the design and deployment of airport multilateration systems. This work covered both standard and Wide Area Multilateration, including algorithms for localization, synchronization, geometry optimization and integrity monitoring.

This research established localization as one of the Group’s central scientific themes: extracting accurate position and timing information from distributed radio sensors became a common thread connecting radar, surveillance and navigation research.

GNSS and satellite navigation

In parallel with radar and multilateration research, the Group developed a strong research activity in Global Navigation Satellite Systems (GNSS).

Research addressed GPS, Galileo and multi-constellation receivers, with particular attention to integrity monitoring, interference detection, localization algorithms and safety-critical navigation applications. The Group also investigated Software Defined Radio approaches and signal-processing techniques for monitoring GNSS signals and mitigating interference.

The combination of radar, multilateration and GNSS research created a common methodological framework based on time, frequency, phase and angle measurements, statistical estimation and sensor fusion.

ADS-B, resilient surveillance and cybersecurity

During the 2010s, the Group’s research increasingly focused on ADS-B and the security and resilience of cooperative air traffic surveillance.

Research addressed ADS-B signal processing, Mode-S transponder identification, RF fingerprinting, message anomalies, jamming and garbling. New approaches were developed for detecting and mitigating interference, including multichannel reception, blind source separation and signal-signature analysis.

The research subsequently moved beyond conventional interference mitigation toward cybersecurity and resilient surveillance, investigating attacks against ADS-B and crowdsourced surveillance networks, aircraft identification and the use of sensor clocks and statistical methods for anomaly detection.

This evolution reflected a broader shift in the Group’s research philosophy: navigation and surveillance systems must not only be accurate, but also robust, resilient and capable of detecting anomalous or malicious behavior.

From terrestrial to space-based navigation

The Group’s expertise in localization, multilateration, GNSS and distributed sensing naturally led to a new research direction: navigation using satellite-based and space-based sensors.

Research investigated the use of high-altitude and satellite platforms for aircraft surveillance and localization, including space-based ADS-B and multilateration. More recently, this work has evolved into the development of GNSS-independent aircraft localization using LEO satellites, combining satellite-based measurements, synchronization and multilateration techniques.

The current SATERA project represents this line of research, focusing on the validation of space-based composite ADS-B and multilateration systems through scalable simulations.

Lunar navigation and navigation beyond Earth

A further evolution of the Group’s research began with the study of navigation systems for lunar exploration.

Since 2021, the Group has investigated the performance and architecture of future lunar satellite navigation systems, including constellations based on ELFO and halo orbits, autonomous orbit determination, time synchronization, differential corrections and inter-satellite measurements.

This research has progressively expanded from performance analysis to more autonomous navigation architectures. Recent work has addressed autonomous orbit determination and synchronization, inter-satellite ranging, lunar surface effects and the integration of additional measurements and sensors to improve navigation performance. Publications on lunar navigation have appeared in venues including Acta Astronautica, Remote Sensing, Sensors, ION GNSS+ and the International Astronautical Congress.

The Group is currently involved in several activities related to lunar navigation, including MOON2, MOON3, ALB (Advanced Lunar Beacon) and Moonlight, with research extending toward future lunar navigation infrastructure and autonomous positioning and timing services.

A continuous research evolution

Although the Group’s research areas have expanded considerably over time, its scientific identity has remained consistent.

The same fundamental questions have guided the work throughout its history:

How can measurements from distributed sensors be processed to determine where an object is, how accurately it can be located, and how reliable that information is?

This question has been addressed in progressively different environments:

1. airport radar, for detecting and tracking aircraft and vehicles;
2. Mode-S and multilateration, for distributed localization and surveillance;
3. GNSS, for global positioning, navigation and timing;
4. ADS-B and cybersecurity, for resilient cooperative surveillance;
5. LEO satellites, for GNSS-independent aircraft localization;
6. lunar satellite constellations and beacons, for navigation beyond Earth.

This continuity between radar, localization and navigation remains at the core of the Radar and Navigation Group’s research.

Research today

Today, the Group brings together expertise in radar systems, signal processing, localization, GNSS, air traffic surveillance, cybersecurity and space navigation.

Current research combines analytical modelling and performance assessment with simulation, experimental measurements and real-world data.

Recent projects span both terrestrial and space applications, including SATERA, Moonlight, Advanced Lunar Beacon, building on a long history of collaborations with industry, universities, research institutions and national and European research programmes.

With this background, the Radar and Navigation Group continues to develop technologies for accurate, autonomous and resilient positioning, navigation and surveillance—from the airport surface to the Moon and beyond.