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FirstGPS Starter Kit User Guide
85
Glossary
Global Positioning
System (GPS)
A system involving the use of satellite technology to
calculate an accurate three-dimensional position. A GPS
system consists of a space segment (up to 24 NAVSTAR
satellites in six different orbits), the control segment
(five monitor stations, one master control station and three
upload stations), and the user segment (GPS receivers).
NAVSTAR satellites carry extremely accurate atomic
clocks and broadcast coherent simultaneous signals.
Horizontal DOP
(HDOP)
See Dilution of precision.
ICD-GPS-200 GPS Interface Control Document, ICD-GPS-200, IRN-
200B-PR-00J, Rev. B-PR, U.S. Air Force, July 1, 1992.
Search for this document on the Web site:
http://www.space.com.af.mil/usspace/gps_support/
gps_documentation.htm.
IF Intermediate frequency.
IODE Issue of data (ephemeris).
LO Local oscillator.
MPM Measurement Platform Module.
NMEA A standard established by the National Marine Electronics
Association (NMEA), that defines electrical signals, data
transmission protocol, timing, and sentence formats for
communicating navigation data between marine
navigation instruments.
PDOP A measure of the quality of the GPS position. PDOP
values below 7 are satisfactory (the ideal PDOP value is
one, and values from 2 to 4 are good). See Dilution of
precision.