Furuno FMD3100, Operator'S Manual

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18-1
18. NAVIGATION SENSORS
18.1 CCRS
This ECDIS employs a Consistent Common Reference System (CCRS) for the acqui-
sition, processing, storage and distribution of sensor information. The CCRS ensures
that all parts of the system uses the same source and values, e.g., speed through wa-
ter, heading, etc. The illustration below shows the CCRS diagram.
The CCRS process NMEA0183 and IEC 61162-1 sentences. No other types of data
(video signals, etc.) are processed.
Check for validity, legitimacy
The system checks received sentences for validity and legitimacy.
Validity check : A sentence's checksum, status (A/V), Mode indicator and setting val-
ues are checked. (If checksum error is found, the sentence is dis-affirmed.)
Legitimacy check : The range and accuracy of a sentence is checked.
If the check for both is OK a valid flag results. If either is invalid, the invalid flag is given.
Types of CCRS
There are two types of CCRS: System and Local. The System CCRS integrates all
navigation devices. In the Local CCRS each navigation device operates independent-
ly.
Representative sensors
If the system has multiple like sensors, the CCRS selects the representative sensor.
Generally, the system uses common representative sensors; however, independent
representative sensors (local representative sensors) can also be used.
CCRS
SENSOR
ADAPTER
Sensors
CCRS CCRS
PCU PCU