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International Civil Aviation Organization Spectrum Seminar Cairo, Egypt June 4-6, 2006

Global Navigation Satellite System (GNSS) Overview and Spectrum Implementation. International Civil Aviation Organization Spectrum Seminar Cairo, Egypt June 4-6, 2006. Basic GNSS System. Core Constellations GPS GLONASS Galileo (under development) Augmentation Systems

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International Civil Aviation Organization Spectrum Seminar Cairo, Egypt June 4-6, 2006

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  1. Global Navigation Satellite System(GNSS) Overview and Spectrum Implementation International Civil Aviation Organization Spectrum Seminar Cairo, Egypt June 4-6, 2006

  2. Basic GNSS System • Core Constellations • GPS • GLONASS • Galileo (under development) • Augmentation Systems • Aircraft-Based Augmentation System (ABAS) • Space-Based Augmentation System (SBAS) • Uses geostationary satellites • India, Japan, Europe, US • Ground-Based Augmentation System (GBAS) • Ground-Based Regional System (GRAS)

  3. a c b Satellite Navigation … Basically Multilateration Multilateration: By knowing your distance from at least 3 points of known-position, you can determine your own position. For Satellite Navigation: a, b & c are satellites, and a fourth is needed to solve for clock variations.

  4. Actual Path Earth’s Ionosphere Assumed Path GNSS Ranging and Timing • Approach: tarrival – ttransmitted~ distance from satellite • Assumes straight path of radio frequency signals • Earth’s ionosphere actually disrupts/bends that path • Augmentations correct for that bend using dual-frequency measurements • Currently not possible directly in aircraft; some signals not protected.

  5. Satellite Navigation’s MissionSBAS/GBAS Implementation SBAS/GRAS GBAS

  6. Satellite Based Augmentation System (WAAS used as example) L1, L2 FAA288-021

  7. Ground Based Augmentation System (GBAS) Architecture Pseudolite Pseudolite GBAS Reference Station (Integrity Accuracy Availability) Processor GNSS Receiver VHF Transmitter Monitor Status Pseudolite

  8. Planned GNSS Modernization • Addition of satellite constellations • Galileo, additional GLONASS satellites • Improves user availability • Addition of civil signals • 1164-1215 MHz band • Facilitates user ionospheric corrections • Possible broadcast of integrity signal • May limit need for external augmentations • Increased power, improved coding • Better resistance to interference

  9. GNSS Frequency Bands

  10. Spectrum Issues • GNSS signals are very weak • ~ 50,000 times weaker than the minimum specified edge-of-coverage DME signal • Aviation spectrum managers must be constantly watching to ensure spectrum incursion from in-band/adjacent band systems does not cause interference. • One example: ITU Footnotes 5.355 and 5.359 • Allow fixed service in GNSS bands in some countries • Countries encouraged to remove their names from the footnotes.

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