Table of Contents
Advertisement
Glossary
Version
7.5
Operator's Manual
based on mathematical models. Local deviations in propagation
speed arc not included. The calculated positions may therefore
differ from positions obtained from dedicated Decca receivers by
several hundred meters.
DEFAULT
A condition that the navigator assumes automatically if no other
condition is initiated by the operator.
DEVIATION (COMPASS)
Magnetic compass reading error due to local magnetic field influ-
ences.
DGPS
See DIFFERENTIAL GPS.
DIFFERENTIALGPS (DGPS)
A method ofrefining GPS position solution accuracy by modifying
the locally computed position solution with correction signals from
an external reference GPS CDU (monitor).
DILUTION OF PRECISION(DOP)
A figure ofmerit for the quality ofGPS-derived position and clock
bias estimates, based on the geometry ofthe selected satellite con-
stellation. The smaller the DOP, the less the magnification of the
range measurement error into position and clock bias errors. Gen-
erally, the more spread out the satellites, the lower the DOP. The
most common DOPs are as follows:
HDOP - Horizontal dilution ofprecision.
GDOP - Geometric dilution ofprecision.
PDOP - Position dilution of precision.
VDOP - Vertical dilution ofprecision.
EARTH FLATTENING COEFFICIENT
See COEFFICIENT OF EARTH FLATTENING.
ECDIS (Electronic Chart Display and Information System)
207
Advertisement
Table of Contents
