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Glossary
nautical mile (nm )
An international unit equal to 6,076.115 feet (1,852 meters)
used officially in the U.S. since 1959. A nautical mile is about
800 feet more than a statute mile.
NMEA
National Marine Electronics Association. The industry group
that has established standards for exchanging data between
electronic navigation equipment. NMEA 0183 is the standard
that's currently in wide use. It specifies the format for sen-
tences containing specific types of data.
NOAA
National Oceanic and Atmospheric Administration.
NOS
National Ocean Service.
paper plotter
A traditional navigation device that uses a paper chart and a
needle to determine position.
Phantom loran
Northstar's exclusive loran-simulation feature that converts
GPS position information into Loran-C TDs—while you navi-
gate with GPS or DGPS.
PPNM
Pulses Per Nautical Mile.
precipitation static
Precipitation-induced electrical charge that can build up on
antenna surfaces, creating poor radio reception. Also known as
P-Static.
queueing waypoints
The process of specifying a trip one or more waypoints in
advance—as you're navigating.
radar
A device or system that emits radio waves for navigational
purposes.
radar plotter
A navigation device tracking radar data as well as waypoints.
rhumb line
A constant, true direction to your destination, which appears
as a straight line on a Mercator grid. Compare with great cir-
cle.
route
A group of two or more pre-defined waypoints that form a con-
nected path to and/or from specific locations. In its simplest
form, a route can be a straight line to a single waypoint.
satellite
An object orbiting the earth. GPS satellites are controlled by
ground stations, and transmit signals that can be used to cal-
culate position and speed.
SA
Selective Availability. The intentional degradation of the GPS
signal by the U.S. Department of Defense.
961 Operations and Reference Manual Rev. D
Page G-5
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