NorthStar 961 Reference Manual page 379

Glossary
statute mile
See mile.
TDs
Time Differences. The measured amount of time—in millionths
of a second—between those loran signals received from the
master and those from the secondary station. These
measurements of relative times of arrival are used to
determine position, according to the Loran-C system.
tide The vertical rise and fall of water caused by the gravitational
pull of the moon and sun.
track
A sequence of position measurements, or a desired line of
travel, defined one second at a time; that is, defined by
actually travelling from point A to point B. Your track is a
continuous record of everywhere your vessel has been.
transducer
A device, often mounted through the hull, which sends and
receives ultrasonic beams that determine seabed conditions
and locate fish. See also echo sounder.
trip A sequence of waypoints, including past, active, and future
ones.
waypoint
A particular position, defined by its coordinates of latitude and
longitude, or distance and bearing, or Loran-C TDs, which is
used as an intermediate or final destination; it can also be
selected by marking fish on the LIVE-DATA screen of the echo
sounder.
XTE
See cross-track error.
961/962 Operations and Reference Manual, Rev. A Page G-7