Furuno FCR-2107 series, Operator'S Manual

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15. Navigation Sensors
15-3
"Pri no alert" and "Sec no alert" can be chosen from the DPGS box if you want to disable the alert "727 DGPS pos.
source change". These selections are intended for the area where the differential coverage is fading. One example is
if you sail along coastline but you are so far away that the differential signal changes its status very often.
The system generates the alert "738 Datum mismatch" (alert numbers are from 738 to 743 depending on the position
receiver) if output datum of a chosen position sensor (status other than Off) is changed from WGS-84 to another
datum or if chosen position sensor does not send datum message. Additional text "datum" appears, in red. Further,
lat/lon values for the position sensor turn red. If the position sensor is also used for system position, Kalman filter
and your ship's position (Lat/Lon values and datum used) are indicated in red. If output datum of a chosen position
sensor is changed from no datum message or another datum to WGS-84 and the operator has used the selection
Primary or Secondary, then the system generates the alert "744 Datum change" (alert numbers are from 744 to 749
depending on position receiver).
Note: The ability to check datum of position is a relatively new feature for position receivers. It was introduced in
standard IEC 61162-1 Ed2, published in July 2000. Only EPFS (for example GPS or DGPS) which has "IEC 61162-
1 Ed 2 (2000-7)" indicated in their type approval certificate can support the ECDIS to detect datum mismatch.
The system generates the alert "407 Position discrepancy" if there is discrepancy in position. Together with this
alert, the system shows the text "Discrepancy" in red in the Position page for a position sensor which has position
discrepancy active.
Enable: Check to align chart, using the "drag and drop" feature.
Chart alignment: Alignment is automatically chosen if the user has defined position offset by using the chart align
feature. The offset values are given in nautical miles and degrees. If position alignment is used, the user is reminded
of it every 30 minutes by the alert "411 ChartAlign: over 30 min".
Dead rec: The system automatically chooses dead reckoning if there are no valid and chosen position sources and if
there are valid and chosen speed and course sources. If the system has chosen dead reckoning, then the user can
enter a new position for the ship in the Lat and Lon fields.
Kalman filter: The Kalman filter calculates estimated position using all valid and chosen position, speed and course
sensors. Choose On to activate this feature.