Furuno FAR21x7 & BB FAR28x7 Operator's Manual BB FAR28x7 Operator's Manual page 187

4. AIS OPERATION
When the fusion criteria is met, the ARP symbol is erased and only the AIS
symbol is displayed. Further, "ARPA FUSION" appears at the bottom right corner
of the display at the time of conversion and the ARP target no. appears next to
the AIS symbol. An ARP target whose speed is less than 1 kt is converted to an
AIS target if it meets all criteria other than course.
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