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International Civil Aviation Organization

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Global Navigation Satellite System (GNSS) Overview and Spectrum Implementation International Civil Aviation Organization Spectrum Seminar Cairo, Egypt – PowerPoint PPT presentation

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Title: International Civil Aviation Organization


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
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
GNSS Ranging and Timing
  • Approach tarrival ttransmitted distance
    from satellite
  • Assumes straight path of radio frequency signals
  • Earths 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 Navigations MissionSBAS/GBAS
Implementation
SBAS/GRAS
GBAS
6
L1, L2
Satellite Based Augmentation System (WAAS used as
example)
FAA288-021
7
Ground Based Augmentation System (GBAS)
Architecture
Pseudolite
Pseudolite
GBAS Reference Station (Integrity Accuracy Availab
ility)
Processor GNSS Receiver VHF Transmitter Monit
or 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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