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

SF-3050 GNSS Product User Guide – Rev I
G-172
GAGAN (GPS Aided Geo Augmented Navigation) an Indian satellite system that
provides a set of corrections for the GPS satellites, which are valid for the Indian region.
They incorporate satellite orbit and clock corrections.
geoid the gravity-equipotential surface that best approximates mean sea level over the
entire surface of the earth. The surface of a geoid is too irregular to use for GPS
readings, which are measured relative to an ellipsoid. Conventionally surveyed positions
reference a geoid. More accurate GPS readings can be obtained by calculating the
distance between the geoid and ellipsoid at each position and subtracting this from the
GPS altitude measurement.
GIS (Geographical Information Systems) a computer system capable of assembling,
storing, manipulating, updating, analyzing and displaying 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 change in the
correction parameters. The transmitted IODC will be different from any value transmitted
by the satellite during the preceding seven days.
JPL Jet Propulsion Laboratory.
Kbps kilobits per second.
L-Band the group of radio frequencies extending from approximately 400MHz to
approximately 1600MHz. The GPS carrier frequencies L1 (1575.4MHz) and L2 (1227.6
MHz) are in the L-Band range.