Second GPS Antenna?

[Two Skippies]

Thank you everyone for your very helpful replies.
I think I have gleaned enough info now to go ahead with my installation.
FWIW, my AIS Transceiver is an Em-Trak Class B with WiFi. The instructions say I can use an external GPS antenna, which I have.

I can set it up with NMEA2000, so I think I'll go with the existing GPS antenna attached to the chartplotter and see how good the signal is.

If its not good enough, at least I now have plan B.

[Cat36Mahalo]

I think there is confusion on what internal and external mean....

From my reading of the documentation In the case of em-trak internal means
Internal to the case of the unit, like a cell phone
External means the GPS antenna is connected to the unit by a cable (not N2K)

This means NOT your chart plotters GPS!!

[evm1024]

As Cat36... noted it is confusing - but even more than he indicates. Context is important.

Part of the confusion is calling an GPS receiver a GPS antenna and the converse.

For example my Camino AIS has an external GPS antenna that feeds an internal GPS receiver. It is also able to get accept GPS sentences from its internal GPS receiver or from an external GPS receiver or other GPS sentence source.

My main ships GPS receiver is a Puck type that incorporates a GPS antenna and receiver in one 3" diameter sensor. It originally came from a Standard Horizons 5" chart plotter CP180). I still have the SH plotter because it is low power and it allows me to control the GPS receiver.

I also have another Standard Horizons chart plotter (CP190i) that has an internal GPS antenna and an internal GPS receiver. I usually use that in the dinghy but it is able to supply GPS sentences to other devices or the whole boat.

There is also the main Raymarine chart plotter. It does not have any GPS of its own. It relies on getting GPS sentences from one of the GPS receivers.

Lastly I have a stand alone SR-161 AIS receiver that can operate without a GPS or can accept GPS sentences from a GPS receiver. This feature allows you to save one port you your chart plotter but nothing else.

Or and don't forget the 2 or 3 handheld GPS receivers that have internal GPS antennas and even one with an external antenna (Garman GPS45) that is pretty much obsolete.

I'm not even going to start on cell phone GPS.

[smac999]

Originally Posted by Two Skippies

Thank you everyone for your very helpful replies.
I think I have gleaned enough info now to go ahead with my installation.
FWIW, my AIS Transceiver is an Em-Trak Class B with WiFi. The instructions say I can use an external GPS antenna, which I have.

I can set it up with NMEA2000, so I think I'll go with the existing GPS antenna attached to the chartplotter and see how good the signal is.

If its not good enough, at least I now have plan B.

I'm pretty sure your AIS is not going to get GPS from the nmea 2000. you need to install and connect the GPS antenna to the AIS that it came with.

[Two Skippies]

Thanks again to all the respondents.
I am gaining knowledge by the minute!
Plan now is to install the lot, then connect the GPS Antenna that I purchased separately, to the AIS.
Doing this effectively means I will have (up to) 3 GPS Antennae working. IE: The original attached to the boat, the one internal in the AIS, and the antenna I am going to add to the AIS.
Then I will work on the configuration of each unit.

[CaptTom]

Originally Posted by Two Skippies

Then I will work on the configuration of each unit.

Without researching your particular unit, let me just say that some have more robust configuration settings than others. You may or may not be able to select which GPS source each device uses. Multiple sources may or may not confuse things.

Likewise, if you have multiple AIS receivers (more likely nowadays with receivers built into VHF radios, alongside a "normal" AIS transceiver) you may find your MFD (or radio) gets confused and decides you're always about to collide with yourself.

[chuckr]

I can only tell you what we did so many years ago and it has been working well for a lot of year.


We have a RayMarine chartplotter and added a ACR AIS with it's own gps and antenna. I do not believe in a splitter on the vhf. I want each to function on it's own. The AIS gps feeds the chartplotter also.


I added a 2nd gps to feed the vhf, a chartplotter in the salon, the ssb and our epirp.


By the way our AIS gps in on the top of our bimini between the solar panels along with the AIS antenna.


the vhf antenna is at the top of the mast. the 2nd gps is on a rail in the cockpit.