NavCom SF-2050 Rev.D - Manual (Page 58)

SF-2050 User Guide - Rev. D
earth at a very high altitude . These distances are used
to calculate the point’s position .
GMT see Greenwich Mean Time.
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 .
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.
L1 carrier frequency the primary
L-Band carrier used
by GPS satellites to transmit satellite data. The
frequency is 1575.42MHz. It is modulated by C/A code ,
P-code or Y-code, and a 50 bit/second navigation
message.
L2 carrier frequency the secondary
L-Band carrier used
by GPS satellites to transmit satellite data. The
frequency is 1227.6MHz. It is modulated by P-code or
Y-code, and a 50 bit/second navigation message.
Glossary-56