One GPS antenna for two or more GPS receivers

HawkX66

Well-Known Member
Jul 27, 2020
1,344
SE Virginia and NH
Boat Info
"Tread Knot"
1997 Sea Ray Sundancer 290DA

2020 F350 6.7L
Engines
454 L29 Carb w/ Bravo III
I'm installing a GPS speedometer in addition to my chart plotter. I've been researching how to connect two devices to one antenna, but it seems to be an expensive proposition. Has anyone come up with another reliable solution?
Here is one I found, but it's $350 and I don't know if it's too high tech a solution for the problem or even right. This one seems more for indoor applications versus marine environment also.

https://www.gpsnetworking.com/products/aldcbs1x2

In the end putting a GPS antenna on either side of the boat isn't a big deal, but I'd rather have one if possible.

Thanks.
 
What GPS equipment are you using? If nmea 2000, they will share the data with all devices on the network. IE Garmin nmea 2000 antenna >> Garmin MFD>> GPS Speedometer?.

Also, every GPS MFD I have ever seen has a speedometer in it. Why would you want a stand alone? You can enable the speedo on almost any view. Raymarine, Garmin, others...
 
Seeing is better than explaining sometimes... I have a Raymarine chart plotter and a dash speedometer that's GPS.

IMG_20201020_151106.jpg
 
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Also, it's an "HV" with Sonar, not the S. Same thing only different. ;-)
 
Gotcha, sorry for any confusion on my end, but those Element units have a built in antenna so the only one you would need is for your GPS speedo. I would think that one needs an external antenna. You would only need one.
 
Gotcha, sorry for any confusion on my end, but those Element units have a built in antenna so the only one you would need is for your GPS speedo. I would think that one needs an external antenna. You would only need one.
I'll have to look into that. I thought my Element had an external one also. Hmmm... You might have just solved my "dilemma". Thanks for the comments.
 
The m330 uses a small "puck" antenna usually with an SMA type connector.
These little pucks are usually amplified, so DC power is feed up the same cable.
Trying to share such an antenna or a similar external antenna (also amplified) from the Multi Function Display/Chart Plotter would likely be electrically more complicated then you think. (without damaging either GPS receiver).

The dash speedo/GPS I cant see the make but likely also uses a small puckk style, they just need to see the sky

I dont see it worthwhile trying to combine the two
 
The m330 uses a small "puck" antenna usually with an SMA type connector.
These little pucks are usually amplified, so DC power is feed up the same cable.
Trying to share such an antenna or a similar external antenna (also amplified) from the Multi Function Display/Chart Plotter would likely be electrically more complicated then you think. (without damaging either GPS receiver).

The dash speedo/GPS I cant see the make but likely also uses a small puckk style, they just need to see the sky

I dont see it worthwhile trying to combine the two
Like you said, it's a little more electrically complicated. Reading up on my systems after the previous comments I figured out what I'd do. The speedo is an Autometer Pro-Comp marine. It needs the puck. The VHF is NMEA 0183, so I could get an adapter cable (nmea 0183 to 2000) and hook it to my MFD which is nmea2000. I think that's all I'd need to do since the Raymarine has an internal GPS antenna. I don't know if I'm going to worry about hooking up the VHF to my MFD. It sounds kind of cool for the AIS and DSC, but I'm not sure if I'd actually need it. Time will tell for that...
 
the m330G has a built in GPS reciever that's the "G" in the model, it will have a puck and a small SMA antenna connector as well as the large VHF Coax connector.
the m330 does not have internal GPS

both support the NEMA 0183 tx/rx

So yes the M330 VHF should be able to use the NEMA GPS data from the Raymarine for things such as transmitting location via DSC (very important for the Distress function)
And the Raymarine should be able listen to the M330 NEMA data for incoming AIS and DSC information.
 
the m330G has a built in GPS reciever that's the "G" in the model, it will have a puck and a small SMA antenna connector as well as the large VHF Coax connector.
the m330 does not have internal GPS

both support the NEMA 0183 tx/rx

So yes the M330 VHF should be able to use the NEMA GPS data from the Raymarine for things such as transmitting location via DSC (very important for the Distress function)
And the Raymarine should be able listen to the M330 NEMA data for incoming AIS and DSC information.
Mine is the M330G. It has the puck. I was just saying that if I wanted to use the GPS enabled services on the VHF without using a second antenna puck, I could probably just plug it into my MFD using a NMEA 0183 to 2000 converter cable. Maybe, maybe not. If I decide to connect the two I'll do a little more research on it.
For now it looks like I'm ok with my original issue which was not wanting two GPS antennas. It turns out my MFD has the internal one so I'll only need one for my speedo.
 

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