Periodic Reporting for period 1 - SATERA (Space-based composite Ads-b and multilaTerarion systEm validation thRough scalable simulAtions)
Periodo di rendicontazione: 2024-07-01 al 2025-06-30
Air traffic surveillance is essential to keep skies safe and flights efficient. Today, most surveillance systems rely on ground-based radars and ADS-B (Automatic Dependent Surveillance–Broadcast) receivers, which work very well over land. However, in oceanic and remote areas, building and maintaining this infrastructure is difficult or impossible. As a result, aircraft flying in these regions must follow wider separation rules, limiting airspace capacity, hindering optimal routing, and leading to higher fuel consumption and increased emissions. This situation is at odds with Europe’s goals for greener aviation, better airspace use, and seamless global connectivity.
To extend surveillance into these regions, space-based ADS-B systems have been deployed. These use satellites in low Earth orbit (LEO) to receive position data from aircraft, route them through an intersatellite network, and downlink the data to ground systems when feasible. This represents a major step forward. However, these systems depend entirely on GNSS (Global Navigation Satellite Systems)—such as GPS or Galileo—which can be affected by jamming, spoofing, or signal errors. GNSS vulnerabilities are particularly relevant in today’s unstable geopolitical environment. This dependency is further aggravated by the lack of an independent method to verify aircraft positions, which is a key limitation for adopting tighter safety standards or performance-based surveillance (PBS) in non-radar areas.
This is where SATERA comes in. The project aims to develop and demonstrate a new type of space-based surveillance system that combines traditional ADS-B with Enhanced Multilateration (E-MLAT). This involves equipping satellites with receivers capable of extracting Time of Arrival (ToA), Frequency of Arrival (FoA), and Angle of Arrival (AoA) from aircraft signals to calculate positions independently of GNSS. This extra layer of information enables cross-checking and enhances the integrity and trust of surveillance data.
SATERA will design and test this concept through a combination of fast-time simulations (FTS) and laboratory experiments, aiming to reach Technology Readiness Level 2 (TRL2). The system’s performance will be evaluated against standards such as EUROCAE ED-142A, focusing on metrics like update rate, latency, and horizontal accuracy.
By enabling dual and independent surveillance channels from space, SATERA supports the SESAR (Single European Sky ATM Research) vision of safer, smarter, and more sustainable air traffic management—especially in airspace without ground-based surveillance infrastructure. The project will contribute to reduced aircraft separation, improved routing efficiency, lower environmental impact, and provide valuable input for future regulation and deployment of space-based solutions across Europe and beyond.
To extend surveillance into these regions, space-based ADS-B systems have been deployed. These use satellites in low Earth orbit (LEO) to receive position data from aircraft, route them through an intersatellite network, and downlink the data to ground systems when feasible. This represents a major step forward. However, these systems depend entirely on GNSS (Global Navigation Satellite Systems)—such as GPS or Galileo—which can be affected by jamming, spoofing, or signal errors. GNSS vulnerabilities are particularly relevant in today’s unstable geopolitical environment. This dependency is further aggravated by the lack of an independent method to verify aircraft positions, which is a key limitation for adopting tighter safety standards or performance-based surveillance (PBS) in non-radar areas.
This is where SATERA comes in. The project aims to develop and demonstrate a new type of space-based surveillance system that combines traditional ADS-B with Enhanced Multilateration (E-MLAT). This involves equipping satellites with receivers capable of extracting Time of Arrival (ToA), Frequency of Arrival (FoA), and Angle of Arrival (AoA) from aircraft signals to calculate positions independently of GNSS. This extra layer of information enables cross-checking and enhances the integrity and trust of surveillance data.
SATERA will design and test this concept through a combination of fast-time simulations (FTS) and laboratory experiments, aiming to reach Technology Readiness Level 2 (TRL2). The system’s performance will be evaluated against standards such as EUROCAE ED-142A, focusing on metrics like update rate, latency, and horizontal accuracy.
By enabling dual and independent surveillance channels from space, SATERA supports the SESAR (Single European Sky ATM Research) vision of safer, smarter, and more sustainable air traffic management—especially in airspace without ground-based surveillance infrastructure. The project will contribute to reduced aircraft separation, improved routing efficiency, lower environmental impact, and provide valuable input for future regulation and deployment of space-based solutions across Europe and beyond.
The SATERA project has progressed as planned, with all scheduled deliverables submitted on time and key technical activities successfully completed. Work to date has focused on defining the surveillance concept, designing the system’s core components, and laying the foundation for its validation at TRL2.
1. System concept and requirements definition
An initial version of the Operational Services and Environment Definition (OSED) has been delivered, outlining the concept of operations, use cases, and performance expectations based on EUROCAE ED-142A.
2. Space segment design (receivers and antennas)
The on-board receiver architecture has been defined, enabling extraction of ToA, FoA, and AoA observables. In parallel, several ADS-B antenna configurations were designed and evaluated to ensure reliable reception in diverse orbital geometries.
3. Constellation and communications
Different LEO constellation designs have been analysed to support multilateration and maximise coverage. Communication protocols, simulators, and security strategies (e.g. routing, encryption, hashing) were also assessed to ensure safe and efficient data exchange between satellites and ground stations.
4. Validation tools and algorithms
A tool based on the Cramér-Rao Lower Bound (CRLB) was developed to estimate achievable positioning accuracy. A System Evaluation Tool was implemented to support upcoming Fast-Time Simulations (FTS). Initial localisation and tracking algorithms based on ToA were developed, including Extended Kalman Filter (EKF), Unscented Kalman Filter (UKF), and H-infinity filters.
These achievements lay the groundwork for the upcoming validation phase and demonstrate steady progress toward validating the feasibility of a composite space-based ADS-B + E-MLAT system for airspace without ground-based infrastructure.
1. System concept and requirements definition
An initial version of the Operational Services and Environment Definition (OSED) has been delivered, outlining the concept of operations, use cases, and performance expectations based on EUROCAE ED-142A.
2. Space segment design (receivers and antennas)
The on-board receiver architecture has been defined, enabling extraction of ToA, FoA, and AoA observables. In parallel, several ADS-B antenna configurations were designed and evaluated to ensure reliable reception in diverse orbital geometries.
3. Constellation and communications
Different LEO constellation designs have been analysed to support multilateration and maximise coverage. Communication protocols, simulators, and security strategies (e.g. routing, encryption, hashing) were also assessed to ensure safe and efficient data exchange between satellites and ground stations.
4. Validation tools and algorithms
A tool based on the Cramér-Rao Lower Bound (CRLB) was developed to estimate achievable positioning accuracy. A System Evaluation Tool was implemented to support upcoming Fast-Time Simulations (FTS). Initial localisation and tracking algorithms based on ToA were developed, including Extended Kalman Filter (EKF), Unscented Kalman Filter (UKF), and H-infinity filters.
These achievements lay the groundwork for the upcoming validation phase and demonstrate steady progress toward validating the feasibility of a composite space-based ADS-B + E-MLAT system for airspace without ground-based infrastructure.
SATERA has already delivered several results that go beyond the capabilities of current operational space-based surveillance systems, which rely solely on GNSS-based ADS-B without independent position verification:
1. A novel receiver architecture has been defined for small satellites to extract ToA, FoA, and AoA measurements from ADS-B signals.
2. Multiple antenna configurations have been designed and evaluated for optimised ADS-B reception in LEO.
3. A synchronisation strategy has been proposed to enable space-based E-MLAT—one of the main technical challenges.
4. A CRLB tool has been implemented to estimate achievable positioning accuracy in varying conditions.
5. Initial tracking and localisation algorithms have been developed using ToA data, including EKF, UKF, and H-infinity filters.
6. A modular System Evaluation Tool has been created to simulate the end-to-end surveillance system under realistic traffic and geometry conditions.
These results represent the first steps towards GNSS-independent, dual-source surveillance from space—an important advancement beyond current GNSS-only solutions.
1. A novel receiver architecture has been defined for small satellites to extract ToA, FoA, and AoA measurements from ADS-B signals.
2. Multiple antenna configurations have been designed and evaluated for optimised ADS-B reception in LEO.
3. A synchronisation strategy has been proposed to enable space-based E-MLAT—one of the main technical challenges.
4. A CRLB tool has been implemented to estimate achievable positioning accuracy in varying conditions.
5. Initial tracking and localisation algorithms have been developed using ToA data, including EKF, UKF, and H-infinity filters.
6. A modular System Evaluation Tool has been created to simulate the end-to-end surveillance system under realistic traffic and geometry conditions.
These results represent the first steps towards GNSS-independent, dual-source surveillance from space—an important advancement beyond current GNSS-only solutions.