Originally Posted by Jim Cate
This is a bit unclear to me... The AIS units with which I am familiar all have built in GPS units with internal antennae. I believe that this is a requirement for FCC and other approval. Most have the option of adding an external antenna if the installation is below decks, especially on metal boats where signal attenuation in the decking is severe.
My el-cheapo Matsutec AIS gizmo has an external GPS antenna. Good and bad really. Bad, another antenna to locate in such a way that it won't get damaged and can actually SEE the satellites, good in that it allows a bit of flexibility in placing the device itself, which incorporates a smallish colour LCD display.
For the OP, assuming you are asking where to put a similar device with a display, I chose to put mine side by side with my plotter for three reasons:
1. It allowed easy comparison of the AIS "radar" with what I can see on the plotter. (Although the AIS data is also displayed on the plotter, see point 3, I do not like to assume this will always be the case.)
2. The plotter is in a convenient location to the helm
, ipso facto, the AIS display becomes likewise.
3. Setting up a NMEA
connection between the AIS unit and the plotter was made simpler by their proximity.
FWIW, my external GPS antenna works perfectly from INSIDE the fibreglass deckhouse. This was unexpected (to me), and made life a bit easier. GPS receivers
have got a lot better in the last few years.
FWIW-2: I chose to use a separate antenna for the AIS, it's a contentious issue here on CF, but I don't like the idea of VHF splitters.