16-1
16. NAVIGATION SENSORS
16.1 CCRS
This chart radar employs a Consistent Common Reference System (CCRS) for the ac-
quisition, processing, storage and distribution of sensor information. The CCRS en-
sures that all parts of the system uses the same source and values, e.g., speed
through water, 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 disaffirmed.
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.
Processor Unit
Processor Unit
SENSOR
ADAPTER
Sensors
CCRS
CCRS
CCRS
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