User's Manual

Table Of Contents
ED 3100 G 140 / 04 (2011-11)
Operating Instructions
III-3 Permanent Area for Navigation
III Main Applications.fm / 10.11.11
III-45
NACOS Platinum
Set Estimated...
The actual position can be entered manually by means of the on-
screen keyboard.
After a position sensor failure the last valid data received from the
sensor are automatically present in the input fields. Be sure to
correct the data input if the last valid data taken over from the
sensor are no longer valid.
Position Monitoring
In addition to the selectable position plot of the 2nd position sensor (see 2nd Past Track) for display in
ECDIS mode, the system provides an automatic position monitoring between the selected sensor and any
other connected position sensor.
In the position instrument you select the main position sensor to be used in the entire system for display
and control purposes. These sensor data are compared to the data received from the secondary available
position sensor. For this purpose the best available secondary sensor will automatically be selected by
the system.
Assumed you have two sensors GPS1 and DGPS2 connected to the system, there are several different
states of the position monitoring process:
1. GPS1 is selected: DGPS2 is used for comparing its position data to the selected position.
2. DGPS2 is selected: GPS1 is used for comparing its position data to the selected position.
3. DR Mode is selected: DGPS2 is used for comparing its position data to the estimated position of the
dead reckoning calculation.
4. Any position (GPS1, -2 or DR Mode) is selected, but none of the secondary sensors is available
(switched off, defective or producing invalid data):
The alarm Redundant Position Lost will be given.
Monitoring Limits
The limits used for the position monitoring process are generated by the system automatically (i.e. there
is no possibility for the operator to have an influence on it). The following table gives an overview about
the dependencies based on the theoretical sensor accuracy.
Table III / 5 Monitoring Limits
Position accuracy Example Limit
1)
1)
To avoid unnecessary alarms, an additional speed dependent
lowest limit is used to filter out the natural position noise.
very good DGPS very small
good GPS small
low Loran high