Meridian Data Transplant CF LP GPS Receiver User Manual

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GIS (Geographic Information System) 
a computer based system that is capable of collecting, managing and analyzing 
geographic spatial data. This capability includes storing and utilizing maps, 
displaying the results of data queries and conducting spatial analysis. 
 
Hot Start 
Start mode of the GPS receiver when current position, clock offset, approximate 
GPS time and current ephemeris data are all available. 
 
L1 frequency 
1575.42 MHz GPS carrier frequency which contains only encrypted P code, used 
primarily to calculate signal delays caused by the ionosphere. 
 
Latitude 
A north/south measurement of position perpendicular to the earth's polar axis. 
 
Longitude 
An east/west measurement of position in relation to the Prime Meridian, an 
imaginary circle that passes through the north and south poles. 
 
Multipath 
Multipath is the reception of a signal both along a direct path and along one or 
more reflected paths. Multipath signals result in an incorrect pseudorange 
measurement. 
 
NMEA (NATIONAL MARINE ELECTRONICS ASSOCIATION) 
A U.S. standards committee that defines data message structure, contents, and 
protocols to allow the GPS receiver to communicate with other pieces of electronic 
equipment aboard ships. 
 
Selective Availability (SA) 
Selective Availability is a process whereby the U.S. Department of Defense dithers 
the satellite clock and/or broadcasts erroneous orbital ephemeris data to create a 
pseudorange error to prevent adversaries from using the extremely accurate GPS 
positioning data.   
 
SPREAD SPECTRUM 
The received GPS signal is wide bandwidth and low power. The L-band signal is 
modulated with a pseudo random noise code to spread the signal energy over a 
much wider bandwidth than the signal information bandwidth. This provides the 
ability to receive all satellites unambiguously and to give some resistance to noise 
 
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