Em-Track vs Digital Yacht AIS Transmitters

[zachduckworth]

Hi,
I am debating getting an Em-Track B 952 and a Digital Yacht AIT 5000 B+.

These two are very similar in specs and price. The Em-track has an internal gps with option for external, the DY modrl has only the external, but it comes with it. I am also interested in how they transfer data.

I already have a self-built AIS receiver system that runs on an rPi with a Glomex active splitter. The splitter feeds AIS data into the rPi which is running OpenCPN and Signal K. In fact, I have two rPi computers, each set up identically except one interfaces with a touch screen and the other with a non-touch screen. Once I start transmitting AIS from the masthead I will set up a stern pulpit mounted VHF antenna that will be completely independent to recieve the AIS via my Glomex and display the data on my two rPi units.

I do not have NMEA on my boat; it came with Seatalk instruments which are all currently not in use. Eventually I’ll update them but not anytime soon.

That said, the Em-Track unit has a 12-point power cable but I can’t figure out how it plugs into the ships power. Do I need to connect it to a NMEA backbone to power it? That would be frustrating. Same question for the Digital Yacht unit. Ideally I would just run the power supply back to my switch board and plug in there with some in-line fuses built in. Is this possible with either unit or am I stuck installing a NMEA backbone to broadcast AIS? Thanks!

[rslifkin]

I have the Em-trak B951 on my boat. The "power" cable has leads for power in as well as a few other things, but the unit takes power from the leads in that cable, not from the NMEA2000 bus. It can output data via NMEA2000, NMEA0183, or USB (and the B952 adds WiFi for that purpose as well).

I've been using mine with the internal GPS antenna and it works well. In my install, the only connections are power, antenna, and NMEA2000. In your case, you'd skip the NMEA2000 and can use either USB or WiFi to get the AIS information to OpenCPN. You wouldn't need to use your existing receiver anymore, as the Em-trak unit both transmits and receives. Although you could also use your existing receiver to receive and ignore the signals received by the Em-trak unit.

[Dockhead]

I'm using the EmTrak and like it.

You don't have an option for an external GPS -- the connector is for an external antenna, which you shouldn't need unless you have the unit buried deep or in a steel hulled boat.

It's not powered from AIS.

The manual has a perfectly clear wiring diagram!

[zachduckworth]

Ok, I see now regarding the Em-Track power, thanks for the info. And the USB would be cool for plugging into the RPi, plus I’d have Wifi (the RPi also has a wifi). I’d still like to have the two receiver units for redundancy. I was not clear that the active splitter could send and receive AIS data, so that clears that up, thanks for the info!