NorthStar 961 Reference Manual page 375

DGPS
echo sounder
ephemeris
fathom
great circle route
961/962 Operations and Reference Manual, Rev. A
Differential Global Positioning System. A technique developed
by the U.S. Coast Guard for correcting basic GPS position data
to increase its accuracy from 20-30 meters (65-100 feet) to 1-3
meters (3-9 feet). The 961XD/962XD uses DGPS, which
requires the ability to receive additional radio signals. See also
GPS.
An instrument that uses sound waves to gather information
about the water directly beneath a vessel, including water
depth, bottom type, and whether there is anything (such as
fish) between the vessel and the bottom.
Data that's used to calculate exact satellite positions,
continually updated and derived from information relayed to
the 961/962 in each satellite's data stream.
ETA
Estimated Time of Arrival at the next waypoint, as calculated
using your present SOG and the distance to the waypoint.
ETE
Estimated Time Enroute to the next waypoint, as calculated
using your present speed and distance to the waypoint.
A depth measurement that equals six feet of water.
GPS
Global Positioning System. Developed by the U.S. Department
of Defense, GPS is a satellite navigation system that computes
your position by using signals from a system of 24
earth-orbiting satellites. Tracking the location of the satellites
is a GPS receiver, which loads this data, and uses it to calculate
your position. This system provides high accuracy anywhere
in the world, at any time of day, under all weather conditions.
However, civilian accuracy is limited to about 20-30 meters
(65-100 feet) with the turning off of Selective Availability. The
961X/962X uses GPS. See also DGPS.
The shortest possible path between two points on the surface
of a sphere.
GMT
Greenwich Mean Time.
GRI
Group Repetition Interval. The identifying time period of
signals emitted by each loran transmitting chain. The code
identifier 9960 (Northeast U.S.) indicates that the gap between
the start of any two adjacent master signals is 99,600
microseconds. GRI code varies depending on geographic
Glossary
Page G-3