I have a "Classic" E-120 with a Raymarine
AIS 500 unit. The AIS unit has a built in spilter and I use my mast head antenna
for optimal range. The software
is easy to use and provides you with an additional tool for navigation
, especially around busy ports
As you are probably aware, IMO and USCG regulations
require most boats over 65 feet to have transmitting AIS (Class A) and more and more recreational boat
under 65 feet are also using Class B AIS units.
The AIS system basically transmits two messages in binary form that your AIS interpets. This is done on two different frequencies. One string is the basic boat information, like name, call sign and dimensions, which transmits less frequently and the other is the dynamic information like position and speed over ground, which transmits regularly.
The most obvious difference between the two classes
of AIS, for our purpose is transmit power and how many times a minutes the unit transmits. Class A transmits at 12 watts and Class B transmits at 2 watts. How often the Class A unit transmits is directly related to the vessel's speed over ground. The Class B unit on the other hand normally only transmits every 30 seconds, reguardless of speed over ground.
Receive distance depends on the enviroment and height of your antenna
. Things like the boat rolling in heavy seas decreases the range dramatically. In calm waters, my AIS Class B transmitts about 8-12 miles and receives about 50 miles of complete AIS infomration and up to 100 miles with partial AIS infomration
As bazzer mentioned, the AIS works at 38,400 BPS, which is not the same speed as most marine DSC
radios. I bring this up because when I first tried AIS, I went with a Nobletech Receiver, which worked off NEMA 0183. Because of the difference in baud rates, the NEMA did not allow the ICOM
radios to use their DSC
functions at this high speed baud rate.
Using the Raymarine AIS units (Receive Only or Class B) elliminates the NEMA this problem, since the unit will use Seatalk
to interphase the AIS unit and the NEMA can be used for other things like your DSC radios.
I think the newer E Series Widescreens have multiple NEMA outputs, which should also correct the conflict, if you can control the baud rates individually