Operation Manual

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User Manual
♦ RTCM = Radio Technical Commission for Maritime Services
The data format created by the Radio Technical Commission Maritime to trans-
mit Differential GPS corrections.
♦ SNR = Signal to Noise Ratio
It is the ratio between the magnitude of a radio signal and the magnitude of
the noise (that is, the interferences). The SRN is expressed in decibels and it
is associated to the GPS satellites signal quality.
♦ SOG = Speed Over Ground
The current velocity at which the vessel is travelling, relative to a ground
location. The SOG is normally provided by the GPS sensor.
♦ SPD = Speed Through Water
The speed of the vessel relative to the water.
♦ Spot Sounding
It is the depth of the water in a specific and charted position. It is represented
on the map by its own value expressed in the current depth unit.
♦ 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 positions are determined by precise timing of the intervals between
reception of pulses transmitted by pairs of stations in the selected chain. Be-
tween any two stations a ship must be located somewhere along a line of
possible positions where the measured Time Difference, TD, between arrival
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 (see also Pair).
♦ Tide
The periodic rise and fall of the surface of oceans, bays, etc., due principally to
the gravitational interactions 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 world-wide. This function can calcu-
late the tide heights for any past or future date and as a by-product of this
calculation will also display the Maximum and Minimum Tide height and time
for the day selected plus the times of Sunrise and Sunset. At some chart
levels, the chart plotter will display a new Tide Diamond Symbol for every Port
or tide point in the database covered by that particular C-CARD.
♦ Tracks + Routes
Recommended and established routes for ships at sea, including traffic sepa-
ration schemes, deep water routes.
♦ TRN = Turning
The difference between COG and BRG. If COG is 80° and BRG is 75°, TRN is 5°
Left.
♦ TTG = Time To Go
The estimated time needed to reach your destination, based on your current
speed and the distance to destination.
♦ TWD = True Wind Direction
Direction of the Wind relative to a fixed point on the earth.
♦ TWS = True Wind Speed
Velocity of the Wind relative to a fixed point on the earth.
♦ Underwater Objects
Objects like obstruction, wreck, cable…