GPS World

Tag: Didier Flament

  • Augmented satnav meeting focuses on future development

    The 6th Satellite-Based Augmentation Systems Interoperability Working Group (SBAS IWG) took place Feb. 5-7 in Delhi, India.

    During the meeting, SBAS developers and operators were joined by users of the systems, with representatives of airlines, aircraft makers and avionics manufacturers. About 50 people in total attended the meeting.

    “Satellite-based augmentation systems deliver the necessary accuracy, integrity, availability and service continuity for aircraft to be able to rely on them though all phases of flight, from cruising in the air to being guided down for landing,” said navigation engineer Didier Flament, head of the European Space Agency’s (ESA) EGNOS and SBAS division, representing ESA at the SBAS IWG.

    The meeting covered the Southern Positioning Augmentation Network (SPAN), which had been born since IWG’s previous gathering six months ago. SPAN, a regional SBAS program, covers Australia and New Zealand.

    The meeting also covered the progress of the four SBAS currently under definition or development: China’s Beidou SBAS, BDSBAS, represented by the China Satellite Navigation Office; South Korea’s KASS, represented by the Korea Aerospace Research Institute; the African and Indian Ocean SBAS, represented by the Agency for Aerial Navigation Safety in Africa and Madagascar; and the Russian Federation’s System for Differential Corrections and Monitoring (SDCM), represented by Russian Space Systems, RSS.

    Current systems are mostly based around the U.S. GPS system (except for SDCM using Russia’s Glonass and BDSBAS using China’s Beidou) but plans are being laid to move to a dual-frequency, multi-constellation version making use of Europe’s Galileo, China’s Beidou and Russia’s Glonass satnav systems later this decade, IWG said.

    Finally, the meeting touched on SBAS research and development, including applying SBAS to Europe’s railways.

    Today, there are 10 satellite-based augmentation systems for satnav that are either in operation or active development, IWG added. The group is working to ensure that the future evolutions of all these systems will operate on a similar basis with common technical requirements, allowing the easy transition of continent-crossing air traffic from one system to another.

  • Upgrades to monitoring stations support EGNOS

    Upgrades to monitoring stations support EGNOS

    Upgrades to the monitoring stations underpinning Europe’s EGNOS satnav augmentation system will support its evolution, said the European Space Agency.

    The current 40 Ranging and Integrity Monitoring Stations (RIMS) sites across Europe and beyond are the bedrock of the European Geostationary Navigation Overlay Service (EGNOS), supplying highly accurate and robust satnav information that can be relied on for safety-critical purposes.

    Thales EGNOS V3 RIMS rack.

    Once a second, these stations gather raw satnav data to transmit information on signal quality and range measurements to the GPS satellites, allowing EGNOS to identify and remove any error in the signals.

    The resulting corrections are then passed to users via a trio of geostationary satellites, delivering a several-fold increase in precision plus “integrity” — a guarantee of navigation service — for safety-of-life applications.

    The result is that the EGNOS-augmented signals are guaranteed to meet the extremely high performance standards set out by the International Civil Aviation Organisation standard, adapted for Europe by Eurocontrol, the European Organisation for the Safety of Air Navigation.

    The signals from space can therefore be relied on routinely for safety-critical tasks, such as vertically guiding aircraft during landing approaches.

    “These current RIMS V2 stations have some inherent limitations, which we’ve sought to tackle in this upgraded V3 design,” said Didier Flament, ESA’s EGNOS programme manager.

    Airbus EGNOS V3 RIMS rack.

    “For instance, our current stations work only with GPS frequencies L1/L2 P(Y), while the future post-2020 EGNOS system will be operating on a multi-constellation basis, additionally employing modernized GPS signals, notably on both the L2 (L2C) and L5 frequency bands, as well as other signals from Galileo, on the similar E1 and E5 frequency bands.

    “Our experience working with RIMS has emphasized the significance on performance of factors such as signal scintillation — caused by the ever-changing ionosphere, the electrically active layer of the upper atmosphere — as well as other environmental threats such as interference and multipath signal reflection.

    “So this upgraded design increased robustness to these factors, based on more stringent development and operating standards, along with innovative radio-frequency environment monitoring.

    “It also includes upgraded receiver technology to accurately monitor potential GPS and Galileo signal distortion — ‘evil waveform’ signal anomalies — in full compliance with international standards.”

    The RIMS V3 stations will be based in the same or similar secure location as today’s stations — typically airports or space-based telecommunication sites.

    Dual tracking antenna concept incorporated in EGNOS V3 RIMS design.

    The individual RIMS antennas themselves can be relatively compact, about 50 cm high, with links to receiver and computing equipment.

    Most of the RIMS V2 station antennas are currently surrounded by dedicated protection structures that limit the impact of interference and multipath local effects.