Vhf splitter for ais transceiver

[gettinthere]

Looking to add an ais transceiver. Using the existing vhf antenna makes sense.
The transceiver splitters are all priced around $250 to 300.
There is a glomax receive only for $30.
How much difference is there between the 2 systems? Will the glomax not work at all or is it a matter of signal degradation? In some technology situations I've seen a "cant work" only because of technical certification. If there is only negligible signal loss, then for me that may be just fine. As an example, a 25 mile vs 24 mile range would be acceptable to me. But 30 vs 5 would not.
So whats the difference between the two?

 

[dlochner]

An AIS transceiver needs a powered splitter. The splitter will disconnect the VHF from the Antenna when the AIS is transmitting and disconnect the AIS when the VHF is transmitting.

The inexpensive passive splitters just prevent the VHF from transmitting into the receiver. They are fine for receive only AIS or FM radios, but will fry the VHF and AIS if they are used with an AIS transciever.

 

[gettinthere]

The glomax is powered but the other aspects of your note sound right for passive. I wonder if its the same for cheap powered splitters.

 

[dlochner]

Between the VHF and the AIS, you'll have north of $1,000 invested. I'd wouldn't want to go cheap on something designed to protect that investment.

The Glomax Website says it is for AIS receiver only applications.

VHF AIS RADIO Splitter • Accessories • Glomex Marine Antennas USA

RA201 is a splitter 12 Vdc that allows the use of just one VHF antenna to simultaneously receive VHF, AM/FM and AIS radio signals.

www.glomex.us

 

[Brian D]

Not going to say either way to do or not do this. But think about this.

If you combine the AIS and VHF into one antenna, one of the two will be disadvantaged. A Class A AIS system operates with 12.5 watts of RF power and sends it position report ever 2 to 10 seconds while under way. At anchor it will send a position report every 3 minutes.

Granted, the AIS burst is probably a short one, but none the less, if you are receiving a distress signal on Channel 16 and your AIS is sending position reports, you might lose some important information.

Next, will the other device sense that there is RF on the line and not transmit? Or, will it also transmit at the same time as the other one? This I don't know. But hopefully the splitter has a way of way of rejecting high level RF (called isolation) to prevent one device from damaging another device.

When I was working in the Satellite field I would set up test benches with splitter combiners so remote terminals could talk to a control terminal (called a closed loop system because it was all on RF cables and not over the air). Because these were very low power systems it was no problem. But once high power RF (in this case several watts) then we had to incorporate in bound blocking filters (pass filters).

There is a lot to go into a properly working splitter/combiner, since that is really what you are trying to install. So make sure the specs are sound because damage to one or both systems is highly probable.

Personally, the best course of action is separate antennas with 3' separation.

JMHO

 

[SEMPERAVANTI41]

What are your thoughts on, AMEC CAMINO-108S Class B AIS Transponder with integrated splitter

 

[jssailem]

Have not used the AMEC Camino. No experience with its functions.
I found it offered on the site (AMEC CAMINO-108S Class B AIS transponder) where I purchased my Vesper XB8000. I have been very pleased with the Vesper unit. It has worked flawlessly for the past 5 years.

I use the wifi feature of the Vesper to connect to laptops, iPhones, and iPads. The data is in my SeatalkNG backbone and is available to Raymarine MFD or Chartploter over the network.

 

[Rodd]

Gents-
I too am thinking of adding AIS wifi transponder. I was looking at the EmTrak unit (with built in splitter), also on the Milltech site. Anyone have thoughts on this one?
Also, will these units take 0183 data wired in separately from different transducers? Or do i need to buy a multiplexer before feeding data into the AIS wifi network?

 

[dlochner]

Also, will these units take 0183 data wired in separately from different transducers? Or do i need to buy a multiplexer before feeding data into the AIS wifi network?

This will depend on the unit you buy. The Vesper Marine XB8000 serves as a 0183 to N2K bridge and has wifi and USB outputs.

 

[jssailem]

Rodd your answer to the 0183 data is maybe...
The EM Trak unit you are considering has 2 ports for 0183 data.
You can attach two "transducers/sensors" producing 0183 data to the unit. This info can be displayed on the chart plotter as shown in the diagram from the EM Track manual.

 

[CarlN]

I would go with the Vesper splitter. Amplifies the signal as well as splits it. And yes - with a poor splitter you could be talking the difference between 5 miles and 30 miles. Or 0 miles and 30 miles. And a splitter is the right choice for a single masted boat. Both VHF and AIS will perform far better with their antennas at the masthead but you can't put two up there without interference. While the first splitters 20 years ago had issues that's long been addressed in newer ones like the Vesper. While there is a theoretical issue of sharing an antenna I've never noticed a difference in real life between a VHF with or without a splitter.

 

[jlp0217]

I don't understand why someone would pay $250 for a splitter when an antenna and cable sells for $135 on this site. I mounted my AIS antenna on my dinghy davits ~8 feet off the water. It works fine - I can see AIS traffic at ranges much farther than I am interested in them. Maybe if I was crossing oceans at night I would want the little extra range a masthead antenna provided, but then I'd likely just swap the two antennae and get more range for the AIS and less for the VHF

 

[dlochner]

I don't understand why someone would pay $250 for a splitter when an antenna and cable sells for $135 on this site. I mounted my AIS antenna on my dinghy davits ~8 feet off the water. It works fine - I can see AIS traffic at ranges much farther than I am interested in them. Maybe if I was crossing oceans at night I would want the little extra range a masthead antenna provided, but then I'd likely just swap the two antennae and get more range for the AIS and less for the VHF

AIS is about seeing and being seen. With the antenna on the rail range is reduced for both reception and transmission. The AIS transmitter is a paltry 2 watts which is less than a handheld VHF. AIS Class B signals will get stomped on by the Class A transmitters so every edge you can give the AIS is to your advantage.

Also, some just don't want the clutter of extra antennas.

Each to their own.

 

[CarlN]

People new to AIS usually don't understand that AIS' primary benefit is to be sure large ships see you. Like it or not, the deck officer on a 800ft ship pays more attention to his AIS display than radar because if something goes wrong, the saved AIS tracks will determine who was a fault.

I find that I don't pick up boats with AIS antennas on a rail or arch farther than 3 miles - but sometimes it's 1 mile. I assume the backstay and other nearby metal is making a mess of the signal radiation. My masthead AIS antenna (through a Vesper splitter) has a range of over 15 miles (I've confirmed this by hailing passing ships).

And as to the cost difference - a good powered splitter like the Vesper takes minutes to install. Properly running coax to a rail mounted antenna or arch can take hours. If you have it professionally done, the job will cost more than the splitter.

 

[DinghySailor]

I think I've found the relevant thread for my question. I'm about to purchase the Vesper Cortex package. The hub has a built-in splitter to accommodate the masthead antenna for the existing VHF, which I intend to keep as a backup. I'll be upgrading the antenna to the Shakespeare AIS 5215-AIS 36". Am I correct in assuming that the coax up the mast will not need replacing? Any recommendations?

 

[JoeWhite]

I would install its own antenna and prevent damage to your VHF. Dedicated antenna does not require power to operate and no electronics to go bad.

 

[dlochner]

I think I've found the relevant thread for my question. I'm about to purchase the Vesper Cortex package. The hub has a built-in splitter to accommodate the masthead antenna for the existing VHF, which I intend to keep as a backup. I'll be upgrading the antenna to the Shakespeare AIS 5215-AIS 36". Am I correct in assuming that the coax up the mast will not need replacing? Any recommendations?

Yes and no. Coax cable has a life span especially when exposed to the marine environment. If your coax is older, then replacing it with a good low loss cable will enhance the performance of the radio. See the link below for more information. Last year I replace my 28 year old coax with Time LMR 400 Ultra Flex. There was a noticeable improvement in range and signal clarity.

AIS operates in roughly the same band as VHF, so only one antenna is necessary if there is an appropriate splitters, not all splitters are are equal. Vesper had a good stand alone splitter that I have used for many years and it works well. So, if I understand you correctly, you want to connect your current VHF to the Cortex as a backup. If the Vesper manual an Garmin say that's OK, then go ahead.

Easy VHF Terminations - Marine How To

If You Don't Know How to Solder..... If you really don't know how to solder a VHF PL259 connector there are other options as you'll see below. This one is laughable, except that when this owner needed his VHF it was no joke or laughing matter that it failed to transmit. The previous owner or...

marinehowto.com

 

[leo310]

I installed a AIS system that came with a splitter but, looking at that safety is number 1 I installed a second vhf antenna on the solar arch. Reason for this is if de-masted I'll still have the AIS and could use it for the VHF radio. Yes range is less but 10-20 miles still give me lots of information.

 

[DinghySailor]

Yes, I'm leaning toward a second antenna, but it would need to be either on a new antenna pole mounted on transom or off the bimini assembly (no arch), which is fairly stout. I'm concerned about transceiver / receiver range with a lower antenna and also signal disruption from rod backstay, etc.

 

[jssailem]

Your AIS like your VHF signal is line of site. Depending on where you sail, you are likely to be getting your relayed data from the satellites transmitted by shore to your AIS receiver. Transmissions will be line of sight. Not so much communication with the 6 foot off the water boats but to the 100ft plus in the air commercial boats, they can hear you.

Try this line of sight calculator (Line of Sight Calculator | Online Line of Sight Calculator App/Software Converter – CalcTown ) to figure out how high to put your antenna. I like the results with my antenna at the top of the mast.
14.8m Antenna Hgt...
Line of sight distance 13.7 km
Radio horizon Service Range 15.8km

Dave's advice on the Coax will help your VHF and AIS systems.