NorthStar 951X Operator's Manual page 190

GPS
Global Positioning System. A navigation system using signals
from earth-orbiting satellites. The system is capable of provid-
ing high accuracy under all weather conditions.
great circle
Shortest possible path between two points on the surface of a
sphere.
GRI
Group Repetition Interval. The characteristic identifying
period of signals emitted by each loran transmitting chain. The
identifier 9960 (Northeast US) indicates that the gap between
the start of any two adjacent master signals is 99,600 microsec-
onds long.
latitude
Imaginary lines on the earth's surface running East/West and
expressed in degrees (0-90) north or south of the Equator.
Used in conjunction with the North/South lines of longitude to
determine position.
leg
The path between adjacent waypoints of a route.
longitude
Imaginary lines on the Earth's surface running North/South
and expressed in degrees (0-180) east or west of the Prime
Meridian (a line running from the North to South Pole, passing
through Greenwich, England).
Loran-C
Acronym for LOng RAnge Navigation. System of land-based
radio transmitters emitting precisely-timed pulses which are
received and translated into position "fixes."
magnetic variation
The difference between magnetic North and true North. Since
the difference varies according to geographic location, the
Northstar 951/952 automatically calculates magnetic variation
and uses it to display bearings as magnetic north. The varia-
tion at any location changes slowly over a period of years, and
the unit compensates, according to the current calendar year.
master
The primary loran transmitter in a "chain" of at least three sta-
tions which initiates the series of coded pulses emulated by
the secondaries.
Phantom Loran
Northstar's exclusive loran-simulation feature that mathemati-
cally converts GPS lat/lon coordinates to loran TDs—in real
time, as you travel—enabling you to display your current posi-
tion as TDs.
Page 180 951/952 Operator's Manual Rev. B