European Geostationary Navigation Overlay Service

European Geostationary Navigation Overlay Service
Name	European Geostationary Navigation Overlay Service
Caption	Coverage area of the EGNOS service.
Country	European Union
Operator	European Union Agency for the Space Programme
Type	Satellite-based augmentation system (SBAS)
Status	Operational
Coverage	Europe
Constellation size	3 geostationary satellites
Precision	< 1.5 m (horizontal)
First launch	2005
Website	[https://egnos-user-support.essp-sas.eu/ EGNOS User Support Website]

European Geostationary Navigation Overlay Service. It is a satellite-based augmentation system developed by the European Union to improve the accuracy and integrity of GPS signals for aviation and other critical applications over Europe. Managed by the European Union Agency for the Space Programme, the system broadcasts correction and integrity information via a network of geostationary satellites. EGNOS is a key component of the European GNSS program, paving the way for the fully independent Galileo system.

Overview

The primary purpose of EGNOS is to enhance the performance of existing global navigation satellite systems, primarily the United States' GPS, for safety-of-life services. It achieves this by providing wide-area differential corrections and integrity monitoring, which significantly reduces errors caused by factors like ionospheric delay and satellite clock inaccuracies. The system is certified for use in aviation under Safety-of-life standards, enabling precision approach operations at many airports. Its development and operation are governed by regulations from the European Commission and implemented by industrial partners like the European Space Agency and Thales Alenia Space.

Technical description

The EGNOS architecture comprises three major segments: the ground segment, the space segment, and the user segment. The ground infrastructure includes a network of precisely surveyed Ranging and Integrity Monitoring Stations across Europe and beyond, which collect GPS data. This data is processed at several Mission Control Centres, such as the one in Toulouse, to generate the correction and integrity messages. The space segment consists of three geostary orbit satellites: Inmarsat-3F2, Inmarsat-4F2, and SES Astra 5B, which broadcast the EGNOS signal on the L1 band. The system complies with international standards set by organizations like the International Civil Aviation Organization and the Radio Technical Commission for Aeronautics.

Service area and performance

The EGNOS service area primarily covers the member states of the European Union, as well as neighboring regions including parts of North Africa and the Middle East. The system provides two main services: the Open Service, freely available, and the Safety-of-Life Service for critical applications. Performance is characterized by high accuracy, with horizontal positioning typically better than 1.5 meters, and stringent integrity guarantees, alerting users within seconds if the system should not be used for navigation. The availability of the service exceeds 99% throughout its core coverage area, which includes major flight routes over the North Atlantic and the Mediterranean Sea.

Development and history

The initial development of EGNOS began in the 1990s through a tripartite agreement between the European Commission, the European Space Agency, and Eurocontrol. The system entered its initial operational phase in 2005, with the Safety-of-Life Service for aviation declared operational in 2011 after extensive testing and certification. Key milestones included the commissioning of ground stations in locations like Reunion and South Africa, and the launch of dedicated navigation payloads on satellites like the SES Astra 5B. The program has undergone continuous evolution, with the EGNOS V3 program now underway to modernize its infrastructure and ensure compatibility with Galileo and modernized GPS.

Integration with other systems

EGNOS is designed to be interoperable with other international satellite-based augmentation systems, such as the United States' Wide Area Augmentation System and Japan's Multi-functional Satellite Augmentation System. This global interoperability is coordinated through forums like the International Committee on Global Navigation Satellite Systems. Furthermore, EGNOS is a fundamental precursor and complement to the Galileo system, with future versions being fully integrated. The system also supports the European Rail Traffic Management System and interfaces with ground-based augmentation systems at major airports like Paris-Charles de Gaulle Airport.

Applications and users

While initially driven by aviation requirements for instrument landing system approaches, EGNOS applications have diversified significantly. It is crucial for maritime navigation in congested waterways like the English Channel and for agriculture, enabling precision farming techniques across the European Union. Other key users include surveying professionals, emergency services such as the Italian Fire Department, and unmanned aerial vehicle operators. The Open Service also supports a wide array of consumer applications in smartphones and vehicle tracking systems throughout Europe.

Category:Satellite navigation Category:European Space Agency Category:Global Positioning System