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OK so why is some AIS illegal in NZ and some not?

 

How can you tell which is which?

 

What's the most likely biggest danger in using one, driving into ship or getting a shitty letter from a little grey man in a polyester suit?

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The issue is the nature of the AIS system. Basically, the standards outline how the units should "share" the allocated frequencies. They should "listen" for a quiet period before transmitting. This is known in the IT world as time division multiplexing. It is critical that ALL units in the area behave as the standards define - If you have a unit that does not behave as the standards outline, it is possible for one unit to disrupt the entire AIS system within range of the faulty/non compliant system. This is a serious issue, not just theoretical! 

 

So, how can you tell? The supplier/manufacturer should be asked to supply a compliance certificate. Make sure that the certificate lists the correct make and model, and at least one of these standards (some are FCC - USA, some are European. I have been given "certificates" for different model numbers, and the wrong standards from Asian manufacturers trying to bypass the (expensive) certifications.

 

IEC 62287, IEC 60945, IEC 61108, IEC 61162, ITU-R M.1371, ITU-R M.825, ITU-R M.1084

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Oh, the biggest danger. Depends, a BIG fine from Radio Frequency Services, and/or hitting something you should have seen, but did not because your unit was jamming both your signal AND theirs, as it had not closed it's transmission correctly... :-( that is worst case of course! 

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Damn right Grant, a dodgy unit is a detriment to everyone. To be completely up front, it is very unlikely that you would get one that actually worked, that is not compliant. However, you never know - who would have thought to put melamine in milk? The certification process it to try to prevent this happening. Honest, reliable companies know they must be certified....

Unfortunately I make the very lowest margin from the Vesper Marine units, so feel free to buy from anywhere. The USA dealers get better buy prices than I do. Doing myself out of business again  :roll: !

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Ah ha, now you say that I do remember seeing a description of how AIS worked and there was limited space, hence that multiplexing thing you mention.

 

I know what you mean about dodgy asian paperwork, you want to see what some do with Certs (supposedly) on our type gear. Rampant dodginess and some is being used in NZ as I write..... by people who do know better.

 

 

Unfortunately I make the very lowest margin from the Vesper Marine units, so feel free to buy from anywhere. The USA dealers get better buy prices than I do. Doing myself out of business again  :roll: !

I know that well as well. The funny thing is I've been buying motorbike and boat bits lately and I'm finding most has been cheaper in NZ than it is buying offshore. I think some just think it's cheaper to shop offshore so don't even bother sussing locally. So I've adopted a ask the locals what they can do, including what can I do to help them possibly do better, before heading offshore. Most are more than happy to be asked and most are happy to work with me to find a way to make it work for both of us. It works. I have got a few bits from offshore but 99% of those things aren't available in NZ.

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Having been looking hard at the options in recent days it is a minefield of information. One has to read the fine print of whether they are just receivers, or are actually sending out your position as well. Not always obvious at first glance. Yes the true send and receive units are still not cheap.

 

If you were stuck on a sea anchor in a storm, having your position beamed out to all around you would be a very good thing...

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