SX BLUE GPS iSXblue II+ GNSSTM, Руководство пользователя

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SXblue Series User Manual 92
GPS antenna. Certain precautions will minimize GPS antenna sensitivity to these
reflected signals. Operating away from large reflective structures such as buildings
or using special antennas and GPS equipment can help to reduce the impact of
multipath. For most consumer-level applications, a small amount of multipath is
tolerable.
GPS Receiver Quality
The quality of a GPS receiver has a dramatic influence on positioning accuracy.
Consumer-based GPS products, such as many affordable handheld and fixed-
mount receivers, typically operate with an accuracy of 3 to 5 meters horizontally
95% of the time. The accuracy of a particular product depends on the specific
receiver’s performance characteristics. Higher accuracy GPS receivers are able
to achieve sub-1 meter horizontal accuracy 95% of the time using real-time DGPS
transmissions. The SXblue receiver falls into this latter category.
Space Based Augmentation Systems (SBAS)
The US Federal Aviation Administration has developed a Wide Area Augmentation
System (WAAS) for the purpose of providing accurate positioning to the aviation
industry. In addition to providing a high quality and accurate service for this
industry, this service is available free of charge to all other civilian users and
markets in Central and North America. This service falls into the greater category
of Space Based Augmentation System (SBAS).
Upon the successful completion of a 21-day test on August 24, 2000, the Federal
Aviation Administration of the United States of America announced that its Wide
Area Augmentation System (
WAAS ) would be running 24 hours per day, seven
days per week from then on. Testing has shown since that this signal is accurate
and reliable. Since the date it was commissioned (July 10, 2003), WAAS has
undergone a few changes in its satellite constellation and coverage (PRN 122 and
134 phased out and replaced by PRN 135 and 138 at new locations; and with the
addition of ground monitoring stations in Canada and Mexico in September 2007).
In summer 2010, PRN 133 has been added to the constellation and in late
December 2010, PRN 135 was recovered after being out of control for a few
months, bringing the total number of operational satellites to three.
Other government agencies have followed the pace and developed compatible
SBAS systems for their respective geographic regions. In Europe, the European
Space Agency, the European Commission, and EUROCONTROL have jointly
developed the European Geostationary Overlay System (
EGNOS ). EGNOS is now
fully deployed and in its pre-operational phase. The system will undergo
certification for safety-of-life applications before becoming fully operational.
Furthermore, on June 28, 2007, the European Space Agency and the Agency for
Security of Air Navigation in Africa and Madagascar have signed a cooperation
agreement with the objective of using satellite navigation to improve air traffic
safety over the African continent.