Background
Air traffic surveillance and airborne collision avoidance systems are critical to the safety and efficiency of aviation in Europe. These systems primarily rely on two frequencies – 1030 MHz and 1090 MHz. 1030 MHz is used by secondary surveillance radars (SSRs), multilateration systems, and collision avoidance systems to interrogate aircraft transponders for essential data such as identification, localization, and status. In response, transponders transmit their replies to the interrogations on the 1090 MHz frequency. For backward compatibility, the newer ADS-B technology also uses 1090 MHz to automatically broadcast surveillance information. In short, these two critical frequencies are the backbone of air traffic control.
The spectrum is vulnerable to threats such as over-interrogation of aircraft transponders or RF interference, which may result in a degradation or even loss of surveillance. This issue can have a particularly negative impact on the European ATC system — directly affecting airspace capacity and posing a substantial risk to its safety and efficiency.
Background
Air traffic surveillance and airborne collision avoidance systems are critical to the safety and efficiency of aviation in Europe. These systems primarily rely on two frequencies – 1030 MHz and 1090 MHz. 1030 MHz is used by secondary surveillance radars (SSRs), multilateration systems, and collision avoidance systems to interrogate aircraft transponders for essential data such as identification, localization, and status. In response, transponders transmit their replies to the interrogations on the 1090 MHz frequency. For backward compatibility, the newer ADS-B technology also uses 1090 MHz to automatically broadcast surveillance information. In short, these two critical frequencies are the backbone of air traffic control.
The spectrum is vulnerable to threats such as over-interrogation of aircraft transponders or RF interference, which may result in a degradation or even loss of surveillance. This issue can have a particularly negative impact on the European ATC system — directly affecting airspace capacity and posing a substantial risk to its safety and efficiency.
The Challenge
European countries operate independent radar infrastructures that each interrogate air traffic within their view. As a result, aircraft transponders are over-interrogated, risking malfunction or unexpected behavior. When coupled with the high traffic density in Central Europe, it creates a major strain on these frequencies. 1090 MHz, in particular, becomes congested during peak traffic hours, causing transmissions to interfere with each other. This prevents successful reception, which forces radars to use higher interrogation rates to maintain the target update probability — further worsening the situation.
In 2011, the European Commission issued the Commission Implementing Regulation (IR) No 1207/2011 which requires member states to prevent excessive interrogations of aircraft transponders. Despite this regulation, in June 2014, some central European ANSPs experienced partial or total loss of detection of multiple targets within their coverage — impacting traffic flow and increasing delays. An investigation by the European Union Aviation Safety Agency (EASA) and EUROCONTROL determined the disruption was due to over-interrogation — transponders received too many interrogation signals on the 1030 MHz band and shut down to prevent overheating, seriously impairing ATC in that airspace.
To prevent future incidents, EASA’s recommendations included enforcing regulation 1207/2011 and stating that member states must monitor and record 1030/1090 MHz usage to ensure interrogations operate within Minimum Operational Performance Standards.
While this event prompted European ANSPs into action, they were hindered by a lack of tools to effectively monitor and manage the congestion. In response, the EC revised IR 1207/2011, extending the deadline for compliance from 2015 to 2020, giving ANSPs more time to find the right solution.
The Challenge
European countries operate independent radar infrastructures that each interrogate air traffic within their view. As a result, aircraft transponders are over-interrogated, risking malfunction or unexpected behavior. When coupled with the high traffic density in Central Europe, it creates a major strain on these frequencies. 1090 MHz, in particular, becomes congested during peak traffic hours, causing transmissions to interfere with each other. This prevents successful reception, which forces radars to use higher interrogation rates to maintain the target update probability — further worsening the situation.
In 2011, the European Commission issued the Commission Implementing Regulation (IR) No 1207/2011 which requires member states to prevent excessive interrogations of aircraft transponders. Despite this regulation, in June 2014, some central European ANSPs experienced partial or total loss of detection of multiple targets within their coverage — impacting traffic flow and increasing delays. An investigation by the European Union Aviation Safety Agency (EASA) and EUROCONTROL determined the disruption was due to over-interrogation — transponders received too many interrogation signals on the 1030 MHz band and shut down to prevent overheating, seriously impairing ATC in that airspace.
To prevent future incidents, EASA’s recommendations included enforcing regulation 1207/2011 and stating that member states must monitor and record 1030/1090 MHz usage to ensure interrogations operate within Minimum Operational Performance Standards.
While this event prompted European ANSPs into action, they were hindered by a lack of tools to effectively monitor and manage the congestion. In response, the EC revised IR 1207/2011, extending the deadline for compliance from 2015 to 2020, giving ANSPs more time to find the right solution.
The Solution
EUROCONTROL recognized the challenge and undertook significant efforts to find an appropriate central solution to this pan-European problem. In 2020, SeRo Systems was selected by EUROCONTROL to provide the platform that collects, processes, and visualizes the vast amount of data collected by a Europe-wide network of 1030/1090 MHz receivers. By leveraging SeRo’s high TRL surveillance data collection and processing architecture, we were able to accelerate the development and implementation process, starting data collection just 2 months after the contract was awarded and delivering the full European Monitoring of Interrogators and Transponders (EMIT) system 4 months later.
EMIT monitors the European airspace to ensure the integrity and resilience of Communication, Navigation, Surveillance (CNS) infrastructure. Designed to provide comprehensive system-wide monitoring, EMIT enables automated detection and analysis of CNS anomalies. Data from the receiver network is collected and processed through SeRo’s servers and database, and the web-based interface allows users to access near real-time and historical data to analyze the performance and behavior of transponders and interrogators. Since its launch in August 2020, EMIT has helped the European air traffic surveillance community not only monitor and manage frequency congestion but also detect and investigate incidents as well as avionics, transponder, and ground radar issues.
Through collaboration and innovation, SeRo and EUROCONTROL are helping maintain the integrity of the CNS infrastructure and delivering safe and efficient operations to support the evolving requirements of the European airspace.
The Solution
EUROCONTROL recognized the challenge and undertook significant efforts to find an appropriate central solution to this pan-European problem. In 2020, SeRo Systems was selected by EUROCONTROL to provide the platform that collects, processes, and visualizes the vast amount of data collected by a Europe-wide network of 1030/1090 MHz receivers. By leveraging SeRo’s high TRL surveillance data collection and processing architecture, we were able to accelerate the development and implementation process, starting data collection just 2 months after the contract was awarded and delivering the full European Monitoring of Interrogators and Transponders (EMIT) system 4 months later.
EMIT monitors the European airspace to ensure the integrity and resilience of Communication, Navigation, Surveillance (CNS) infrastructure. Designed to provide comprehensive system-wide monitoring, EMIT enables automated detection and analysis of CNS anomalies. Data from the receiver network is collected and processed through SeRo’s servers and database, and the web-based interface allows users to access near real-time and historical data to analyze the performance and behavior of transponders and interrogators. Since its launch in August 2020, EMIT has helped the European air traffic surveillance community not only monitor and manage frequency congestion but also detect and investigate incidents as well as avionics, transponder, and ground radar issues.
Through collaboration and innovation, SeRo and EUROCONTROL are helping maintain the integrity of the CNS infrastructure and delivering safe and efficient operations to support the evolving requirements of the European airspace.
Specifications
Volume of Data Collected: Since initiating data collection in March 2020, our system has collected an impressive 3.15 trillion signals. This can be broken down into 2.28 trillion downlink and 870 billion uplink signals.
Growth Rate: The figure above illustrates the consistent growth of the network and the volume of data we manage. Currently, our system adds nearly 5 billion signals to the dataset every day.
Peak Traffic Capabilities: At peak traffic hours, our advanced system collects, processes, stores, and visualizes a staggering 90,000 signals every second. These signals are captured by the EU-wide network of receivers and are subsequently streamed to our system through a secured internet connection.
Deduplication Algorithm: Our backend uses our proprietary deduplication algorithm. This algorithm groups data points received from various receivers that belong to a single transmission. This ensures that our system fully exploits the network redundancy (as visualized in the attached figure below) to provide the most precise and comprehensive overview of both the spectrum and transponder load.
Online Analysis: Once the data is preprocessed, our system generates a range of metrics. These metrics are key to EMIT's users, offering them the tools to automatically detect and analyze over-interrogations and other issues associated with the 1090 and 1030 MHz frequencies.
Data Archiving & Access: For in-depth analysis and retrospective insights, EMIT has incorporated an archive function. Users can conveniently download raw data, ensuring they have all the resources they need for comprehensive analysis and reporting.
Sensor Operations: EMIT automatically monitor sensor status and notifies operators about problems with their installations such as internet connectivity or GPS synchronization issues.
For more information, please contact us.
