NavCom SF-3050 Rev.B - Manual (Page 191)

SF-3050 User Guide – Rev B
geographically referenced information, i.e. data
identified according to their locations. GIS technology
can be used for scientific investigations, resource
management, and development planning. GIS
software is used to display, edit, query and analyze
all the graphical objects and their associated
information.
Global Positioning System (GPS) geometrically,
there can only be one point in space, which is the
correct distance from each of four known points. GPS
measures the distance from a point to at least four
satellites from a constellation of 24 NAVSTAR
satellites orbiting the earth at a very high altitude.
These distances are used to calculate the point’s
position.
GLONASS (Global Orbiting Navigation Satellite
System) the Russian Federation’s GNSS system,
managed by the Russian Space Forces (Russian:
VKS). GLONASS uses the same concepts for
positioning as GPS.
GMT see Greenwich Mean Time.
GNSS Global Navigation Satellite System.
GPS see Global Positioning System.
GPS time a measure of time. GPS time is based on
UTC, but does not add periodic ‘leap seconds’ to
correct for changes in the earth’s period of rotation.
As of September 2002 GPS time is 13 seconds
ahead of UTC.
Greenwich Mean Time (GMT) the local time of the
0° meridian passing through Greenwich, England.
HAE see altitude, and ellipsoid.
IODC Issue of Data, Clock - The IODC indicates the
issue number of the data set and thereby provides
the user with a convenient means of detecting any
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