Trimble Inc. 55800 Manual De Usuario
Glossary
1 68 SPSx50 Modular GPS Receiver User Guide
VRS
(Virtual Reference Station)
A VRS system consists of GPS hardware, software, and communication links. It uses
data from a network of base stations to provide corrections to each rover that are
more accurate than corrections from a single base station.
data from a network of base stations to provide corrections to each rover that are
more accurate than corrections from a single base station.
To start using VRS corrections, the rover sends its position to the VRS server. The VRS
server uses the base station data to model systematic errors (such as ionospheric
noise) at the rover position. It then sends RTCM correction messages back to the
rover.
server uses the base station data to model systematic errors (such as ionospheric
noise) at the rover position. It then sends RTCM correction messages back to the
rover.
WAAS
(Wide Area Augmentation System)
WAAS was established by the Federal Aviation Administration (FAA) for flight and
approach navigation for civil aviation. WAAS improves the accuracy and availability of
the basic GPS signals over its coverage area, which includes the continental United
States and outlying parts of Canada and Mexico.
approach navigation for civil aviation. WAAS improves the accuracy and availability of
the basic GPS signals over its coverage area, which includes the continental United
States and outlying parts of Canada and Mexico.
The WAAS system provides correction data for visible satellites. Corrections are
computed from ground station observations and then uploaded to two geostationary
satellites. This data is then broadcast on the L1 frequency, and is tracked using a
channel on the GPS receiver, exactly like a GPS satellite.
computed from ground station observations and then uploaded to two geostationary
satellites. This data is then broadcast on the L1 frequency, and is tracked using a
channel on the GPS receiver, exactly like a GPS satellite.
Use WAAS when other correction sources are unavailable, to obtain greater accuracy
than autonomous positions. For more information on WAAS, refer to the FAA website
at http://gps.faa.gov.
than autonomous positions. For more information on WAAS, refer to the FAA website
at http://gps.faa.gov.
The EGNOS service is the European equivalent and MSAS is the Japanese equivalent
of WAAS.
of WAAS.
WGS-84
WGS-84 is an abbreviation for World Geodetic System 1984. WGS-84 has superseded
WGS-72 as the datum used by GPS since January 1987.
WGS-72 as the datum used by GPS since January 1987.
The WGS-84 datum is based on the ellipsoid of the same name.