T&T: AIS

[Steven Dubnoff]

>1. I presume that an AIS system requires at least one or possibly two
>additional VHF antennas. How many to be exact?

It requires one antenna.  Alternatively, you could use a splitter:

http://www.milltechmarine.com/VHF_splitter.htm



>2. I understand that most recreational boats will use a passive Class B
>receive-only type of AIS. Is an active mode desirable (or permissible)
>and if so, how much does it cost versus receive only mode?

Actually, there are two classes of transmit/receive AIS units (A and 
B), plus receive only units.  There are currently no FCC certified 
Class B units on sale in the US, so if you want to transmit, you will 
need an expensive class A unit.

My advise is to get a receiver (less than 200 bucks).  It is not yet 
clear whether big ships will even bother to look at Class B units.



>3. Does the AIS receiver interface with a PC-based chartplotting system
>or can it work directly with a dedicated chartplotter. If so, which
>types? Is the interface by USB or 232 serial cables?

It depends. If you are using a dedicated chartplotter, it will need 
to be a new one.  PC stuff changes faster.  Coastal Explorer has fine 
AIS support.  Most of the receivers have RS-232 output.  The fine 
SeaCAS unit talks USB.

For lots of reading about AIS, see:

http://www.panbo.com/archives/cat_ais.html

Best,

Steve




Steve Dubnoff
1966 Willard Pilothouse
www.mvnereid.com
sdubnoff at circlesys.com