User's Manual

Table Of Contents
NACOS Platinum
ED 3100 G 140 / 04 (2011-11)
Operating Instructions
III-3 Permanent Area for Navigation
III Main Applications.fm / 10.11.11
III-40
Course over Ground - COG
1)
The value for course over ground is calculated
- by use of the heading and the log sensors (a bottom-track-log for example) or
- computed from the measured values of a sensor and additional information (a water-track-log and
the values for drift and set for example).
- It can also be computed from the difference of own-ship positions within a specified time (normally
delivered by a position sensor in a specific telegram).
The method the COG is computed depends on the sensors selected. For example, in case of the speed
log its longitudinal and transversal speed values together with the heading value are used to calculate
the true course vector over ground. The system decides itself and chooses the best and most accurate
way to compute the COG. In any case the indicated COG is based on the data received from the speed
sensor shown behind the SOG value.
The COG/SOG instrument in the Permanent Area displays course and speed over ground as a data
pair describing the direction and the length of the speed vector over ground.
Speed over Ground - SOG
1)
AUTO
Means that the speed over ground sensor is chosen by the system automatically.
The best available sensor will be used. If a failure occurs on the actual sensor,
the backup sensor is chosen and a warning is given.
Manual Sensor Selection
Log x
The selected speed log is used as system sensor for ground speed. If the selected
log is a single axis log, it is advisable to enter set and drift to correct for tidal
currents.
GPS x
Position sensors may be selected as input for SOG values. See also hint on page III-37 for details.
REF TGT
REF TGT
speed input can only be selected on radar systems and if, as a minimum, one tracked target
is selected as a reference target (shown as on the PPI, see chapter A - 7 on page A-55 for
details.)
STW
Sets the SOG to the same value as STW. In this case it is advisable to enter set and drift to correct for
tidal currents.
If set and drift are not set or initialized, it may happen that the COG/SOG data will be made invalid.
1)
The selected COG/SOG vector for speed over ground is used as the data source for Ground Stabilisation of
the targets in the radar PPI/chart area.
R1