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6.6 WHAT IS THE RANGE FOR AIS RECEIVERS?
S
ince AIS uses similar frequencies as a marine VHF radio, it has similar radio
reception capabilities - which are basically line of sight. This means that the
higher the VHF antenna is mounted, the greater the reception area will be.
Reception from Class A vessels that are 20 or even 30 miles away on open
water is not uncommon as their antennas are mounted high off the water. Class
B transponders use lower power for transmissions; therefore, you can expect
Class B vessels to be acquired when they are 5 to 10 miles away.
NOTE
For additional information on AIS visit the USCG website:
<http://www.navcen.uscg.gov/marcomms/ais.htm>
6.7 Accuracy of COG
The error in the COG (the path of the antenna position over ground) due to the
actual ship’s speed over ground shall not exceed the following values:
Speed range (knots)
Accuracy of COG output to user
0 to ≤1 knot
Unreliable or not available
>1 to ≤17 knots
±3°
>17 knots
±1°
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