Use an Existing Marine VHF for AIS

[ami keren]

Can I use an existing marine VHF useing channel 87/ 88 for AIS?
Ami

[Jon Hacking]

Hi Ami - & Welcome to Cruisers Forum!

You certainly can't do so legally. I suppose a radio & computer guru could coble something together, but you risk jamming up the whole system & threatening marine traffic safety.

Why bother? AIS receivers were under $190 when I bought mine 4 years ago. And Transceivers are now under $495. I think it's the best thing since GPS.

[jerrymc]

Yes, it is possible, if you're well versed with electronics, in particular, the workings of a VHF receiver & willing to tear apart your VHF & tinker with it, but it may be more trouble than it's worth, considering you can buy a Class B receiver for about $200.

This link explains how to tap the discriminator output of a VHF radio..it even has schematics for many well-known brands: Discriminator Output

[David M]

I wouldn't risk the FCC fines of potentially bringing down the AIS system. Peoples lives are at stake now with AIS working, especially in harbors with lots of commercial traffic including high speed ferries. VTS also uses AIS for identifying and informing commercial vessels.

Also, If you have an AIS transceiver then please leave it off if you are not using it. People who ignorantly or selfishly do this are cluttering up the system....especially yachts sitting at their marina. The SF Bay has plenty of them now, unnecessarily hogging and clogging the system. Don't force the authorities to make separate sytems for yachts and for commercial vessels where commercial vessels can tune yachts out just so they can use the system. That just might happen if this abuse continues.

Please spread the word to anyone you know who might be abusing the AIS system.

Stepping off my soapbox.

[jerrymc]

QUOTE=Jon Hacking;755074]Hi Ami - & Welcome to Cruisers Forum!
You certainly can't do so legally. I suppose a radio & computer guru could coble something together, but you risk jamming up the whole system & threatening marine traffic safety.
GPS.[/QUOTE]
Wrong! There is nothing illegal about modifying an existing VHF radio that already receives channels 87/88 so that you can decode the incoming signals. If you read the OP's question, it has to do with RECIEVING ais signals.

Originally Posted by David M

I wouldn't risk the FCC fines of potentially bringing down the AIS system.

And, pray tell, how would one "bringing (sic) down the AIS system" by receiving AIS signals, through a radio that is equipped to receive them?

Methinks you fellas oughta read posts & responses before jumping to conclusions or lecturing.

[Jon Hacking]

Originally Posted by ami keren

Can I use an existing marine VHF using channel 87/ 88 for AIS? - Ami

Wow, JerryMC - for a newbie on CF, you're pretty aggressive. I suggest you tone it down a bit. There's no part of the above that suggests Ami wants to use it only for receiving. I think David's (& my) posts were completely appropriate. Perhaps you were making an assumption?

[Jon Hacking]

Originally Posted by David M

...If you have an AIS transceiver then please leave it off if you are not using it. People who ignorantly or selfishly do this are cluttering up the system... Don't force the authorities to make separate systems for yachts and for commercial vessels ...

David, I'm a bit surprised at this. We haven't cruised the US but here in Malaysia they have AIS repeaters running for 200nm from Singapore to Port Klang, up the very crowded Malacca Straits. I can see ~1,000 ships on AIS. But both MaxSea & OpenCPN seem to handle this "clutter" OK.

When I'm navigating, I'm only interested in AIS targets (both class A & B) that are near me or going to be near me. My software doesn't seem too fussed with targets that are further away or anchored/moored. Are we in danger of exceeding the limits of AIS? Or is it more a problem with folks receivers?

Are there really moves afoot to create separate systems? Most merchant sailors I've talked to say they want to see ALL boats out there.

I've seen folks complaining & posting AIS screen shots of yachts sitting in marinas, but the complaints seem hollow & unfounded as there are few other AIS targets shown. Is there a real problem, or is it just a perceived problem?

If the system isn't about to break down, there are valid social reasons to keep our AIS on at anchor. OK, not what AIS was designed for but still useful to let friends know where we are. We only xmit for a few msec every 3(?) minutes when we're at anchor. That may "clutter" someone's screen, but it's hardly a bandwidth concern.

[dacust]

Originally Posted by Jon Hacking

Wow, JerryMC - for a newbie on CF, you're pretty aggressive. I suggest you tone it down a bit. There's no part of the above that suggests Ami wants to use it only for receiving. I think David's (& my) posts were completely appropriate. Perhaps you were making an assumption?

Actually I thought jerrymcs post was appropriate. The OP did not say if they were planning to transmit, but you and David both replied as if they HAD said that. I think the appropriate response would have been to say "You didn't say if you plan to transmit or only receive, but, if you were thinking of transmitting, WARNING..."

-dan

[David M]

Originally Posted by Jon Hacking

David, I'm a bit surprised at this. We haven't cruised the US but here in Malaysia they have AIS repeaters running for 200nm from Singapore to Port Klang, up the very crowded Malacca Straits. I can see ~1,000 ships on AIS. But both MaxSea & OpenCPN seem to handle this "clutter" OK.

When I'm navigating, I'm only interested in AIS targets (both class A & B) that are near me or going to be near me. My software doesn't seem too fussed with targets that are further away or anchored/moored. Are we in danger of exceeding the limits of AIS? Or is it more a problem with folks receivers?

Are there really moves afoot to create separate systems? Most merchant sailors I've talked to say they want to see ALL boats out there.

I've seen folks complaining & posting AIS screen shots of yachts sitting in marinas, but the complaints seem hollow & unfounded as there are few other AIS targets shown. Is there a real problem, or is it just a perceived problem?

If the system isn't about to break down, there are valid social reasons to keep our AIS on at anchor. OK, not what AIS was designed for but still useful to let friends know where we are. We only xmit for a few msec every 3(?) minutes when we're at anchor. That may "clutter" someone's screen, but it's hardly a bandwidth concern.

I am referring to boats not underway tied up to docks transmitting to what amounts to unnecessary clutter on the screen. I was also not referring to boats at anchor.

I wish every vessel out there was transmititng AIS, when they are underway or at anchor.

[ami keren]

I plan only to receive,
Ami

[yachtvalhalla]

Originally Posted by ami keren

I plan only to receive,
Ami

Hi Ami and welcome to the forum.

Thanks for the clarification but I knew intuitively what you meant. And agree with the answer that it's probably not worth it. Receivers are affordable enough and don't fall for the suggestion to use your existing VHF antenna with a splitter .. works electronically but not in practice. (Why? Because if you need to talk with a ship that may well be of concern to you then you are blocking the critical AIS data that might help you understand the situation while you are talking).

And please don't be put off by people who like to rant ... some of them seem to search for ways to show their ignorance.

So fire away the questions ... there really are no dumb questions, only sometimes you get dumb answers.

Happy sailing,

Terry

[ami keren]

The idea is to use in delivey, my 5w portable vhf, for AIS, in open CPN, on my leptop.
Ami

[nohal]

Ami...
after reading Discriminator Output and looking inside my handheld VHF, I just bought the 120EUR AIS receiver at Radar Gadgets - ADS-B aircraft radio receiver - Virtual Radar Looks like a toy but works acceptably and fits in any pocket.
I normally like playing with the solder, but in this case it was not worth it... For any solution you choose, remember the "the higher the antenna, the better" stuff.

Pavel

[jerrymc]

Originally Posted by Jon Hacking

Wow, JerryMC - for a newbie on CF, you're pretty aggressive. I suggest you tone it down a bit. There's no part of the above that suggests Ami wants to use it only for receiving. I think David's (& my) posts were completely appropriate. Perhaps you were making an assumption?

Jon:

You're right..I was overeacting to what I felt were negative responses to the OP's simple inquiry. A better answer would have been the reference below from Automatic Identification System - Wikipedia, the free encyclopedia

Computing and networking

Several computer programs have been created for use with AIS data. Some programs (such as ShipPlotter and gnuais) use a computer to demodulate the raw audio from a modified marine VHF radio telephone when tuned to the AIS broadcast frequency (Channel 87 and 88) into AIS data. Some programs can re-transmit the AIS information to a local or global network allowing the public or authorized users to observe vessel traffic from the web. Some programs display AIS data received from a dedicated AIS receiver onto a computer or chartplotter. Most of these programs are not AIS transmitters, thus they will not broadcast your vessel's position but may be used as an inexpensive alternative for smaller vessels to help aid navigation and avoid collision with larger vessels that are required to broadcast their position. Ship enthusiasts also use receivers to track and find vessels to add to their photo collections.[4]

[ami keren]

I decide to buy
MarineGadget Radar - AIS Receiver
thank's

Ami