Si-text trawl plot 12, User Manual, Page: 112 / 118

114 User Manual
OSGB = Ordnance Survey of Great Britain
A coordinate system describing only Great Britain. Generally used with GBR36 datum, which also
describes only Great Britain. This coordinate system cannot be used in any other part of the world.
Port Info
The Port Info function is a combination of a new Port Info database containing all the relevant Safety
and Navigational information normally found in good pilot books and a new presentation software
which displays special Port Facility Symbols.
Ports & Services
Areas along shore with facilities for mooring, downloading and uploading of ships, generally sheltered
from waves and winds. Port installations are piers, wharves, pontoons, dry docks, cranes... .
Route
Sequence of Waypoints connected by segments. Among the available Routes, only one is the active
Route, which is shown by a straight line and arrows to indicate the direction. The first Waypoint of the
active Route is surrounded by a circle (see Par. 4.1.1).
RTCM = Radio Technical Commission for Maritime Services
The data format created by the Radio Technical Commission Maritime to transmit Differential GPS
corrections.
SET
Direction of drift.
Simulation
Used in order to use your chartplotter without input data. It generates a display with a moving vessel,
so that you can practice using the controls in safety.
SNR = Signal to Noise Ratio
The ratio of the magnitude of a signal that of the noise (interference).
SOG = Speed Over Ground
A calculation of the rate of movement of the ship over the ground.
Speed
The current velocity at which you are travelling, relative to a ground location.
SPS = Standard Positioning Service
The civilian-access signal broadcast by the GPS satellites.
STR = Steering
The difference between COG and CTS. If COG is 25° and CTS is 30°, then STR is 5° Right.
TD = Time Difference
Loran-C positions are determined by precise timing of the intervals between reception of pulses trans-
mitted by pairs of stations in the selected chain. Between any two stations a ship must be located
somewhere along a line of possible positions where the measured Time Difference, TD, between ar-
rival of pulses from those stations would be observed. The TD is measured from the time of reception
of the master station signal to the time of reception of the slave station signal.
Tide
The periodic rise and fall of the surface of oceans, bays, etc., due principally to the gravitational interac-
tions between the Moon and Earth.
Tide Info
The Tide Info feature is the combination of a new tide heights database that will be included within
new C-CARDs and new features which calculate the tide graph for all primary and secondary ports