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Hi everyone --can l pick your brains please--I have an issue with my AIS. It is a Nais 400 (B&G) and is linked to my B&G Chart plotter--It has worked extremely well , 2x RNI and multiple coastals/races around the harbour.

The  chart plotter is showing all contacts and providing readings as it should be , and its not on silent mode. What isnt happening is that other receivers aren't seeing me--I have checked this with friends who have  AIS receivers and on marine traffic etc .

When trying to isolate any thing that may affect signal receipt/transmission the appropriate lights come on (on the unit )and then just settles down with only the amber/standby light showing (continuously )-- my thought is that it's not receiving a GPS signal /position to transmit-- everything else appears to be working well-

Does anyone else have any similar experience/ideas/solutions 

Andrew 

(Duty Free )

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We had same issue leading upto RNI and it was the gps aerial was faulty.

If you plug in with laptop and download software you will be able to see if it was picking up satellites.

Ours was picking up satellites but very weak signal so no proper fix on them, swapped aerial out after talking with navico and it worked straight away.

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Most commonly found issue is the antenna. Can be a poor crimp, plu259 plugs are notorious for losses. Receiving ok does not mean your antenna is ok. The antenna and the coax both degrade. If it's over 10 years old I'd replace the antenna and the coax. I actually have one at home ,  with coax, awaiting install on Island Time.

As above though, if the unit has no GPS fix it won't transmit. This can be seen from the software with a PC, the diags in the app are useful.

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Would the chart plotter still have a fix if this is the case ?

not up on b&g but my ray gear has a screen showing satellites and signal strength 

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3 hours ago, Jon said:

Would the chart plotter still have a fix if this is the case ?

not up on b&g but my ray gear has a screen showing satellites and signal strength 

Yep, chart plotter has its own, built in gps. The ais has (usually) its own gps antenna. The gps display on the Raymarine or B&G display is the one they are using - can be internally- usually, or external for some boats, esp steel ones.

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2 hours ago, lateral said:

Same subject but bit of a drift.

Are most gps processors in the AIS unit and the antenna is passive just an aerial? Can you use a active antenna that outputs gps sentenced thru the data input wire of the AIS as a back up if your antenna goes south? Thing is plotter and active gps would have to share ground. Can’t see that working. Perhaps rs232/422/485 converter?

The earlier matsutec doesn’t  have a db9 as do later ones. Can’t see why the data I/O can’t send 0183 back to AIS from Zeus 2/ networked gps and just flag the passive aerial/dome.

Havent played around yet, just got my cables and mmsi done. Will try it and see what happens.

 

Yes, can be done. Most, but not all, AIS units use active antennas...

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14 hours ago, Island Time said:

Yep, chart plotter has its own, built in gps. The ais has (usually) its own gps antenna. The gps display on the Raymarine or B&G display is the one they are using - can be internally- usually, or external for some boats, esp steel ones.

Yep now I think of it I do have two external go’s antennas, one must be for ais.

Andrew (Duty Free) should try a new antenna first then

 

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On 2/07/2021 at 7:58 AM, Jon said:

Yep now I think of it I do have two external go’s antennas, one must be for ais.

Andrew (Duty Free) should try a new antenna first then

 

Yep just installed my b & g ais unit and seem to remember seeing in the manual it won't take GPS info from a plotter/other source, only from its own antenna. Definitely sounds like duty free is worth trying a new antenna. 

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10 hours ago, raz88 said:

Yep just installed my b & g ais unit and seem to remember seeing in the manual it won't take GPS info from a plotter/other source, only from its own antenna. Definitely sounds like duty free is worth trying a new antenna. 

Are they a powered antenna ?

could have just lost power ? Or connection  to base if power fro that, be worth checking

 

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Part of the ais standard is that they are supposed to run fully independently of the network, although some don't meet the standard ( cheap Asian mostly,  like matsutec)

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Thanks everyone --the antenna was where I had come to--need to download proAIS2 diagnostic to check this out but may need a new antenna--

IT --do you supply/sell  these 

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