Intermittent AIS issue ...any ideas on how to solve ?

[MikeCC]

Easiest is to hook up a laptop to AIS and get the diagnostics screen information. It's likely to use the ProAIS2 software, widely available to download if you don't have already. The AIS diagnotics will show you what GPS signals it is getting and also SWR for the antenna setup. Will save a lot of time compared to physical elimination.

 

[Bilgediver]

Easiest is to hook up a laptop to AIS and get the diagnostics screen information. It's likely to use the ProAIS2 software, widely available to download if you don't have already. The AIS diagnotics will show you what GPS signals it is getting and also SWR for the antenna setup. Will save a lot of time compared to physical elimination.

This is an old thread Mike and the OP did not respond much before.

 

[greeny]

Don’t you just hate intermittent electric problems

never got to bottom of issue but it faded into background as seemed to be transmitting fine when I used the boat, and or requested a AIS check as well as a radio check from our friendly and helpful jersey coastguard

it was working and transmitting and I could see us when we set off for a day trip on Sunday, indeed I did an AIS with CG and I could see us on marine traffic as we left.

it stopped just as we got back after 12 hours out and has doggedly refused to send out a signal since ...we were in the harbour entrance but still underway when it stopped sending a signal

I have checked AIS unit and signal splitter and both appear to be operating ok (based on little indicator lights)

I AM getting AiS inputs from other boats onto the chart plotter, but possibly not at full range.

I have connected AIS directly to aeriel bypassing splitter and getting nothing on the transmission front

I am increasingly thinking an aerial issue, but my radio checks with CG are fine

my next step is to borrow an emrgency VHF aerial and attach it and see if that makes any difference.

any other bright ideas ?

Post 7

 

[Bathdave]

Post 7

whilst I appreciate any input, With respect I think you’re missing the point

neither the coastguard or my friends boat were picking up the transmission either so it clearly isn’t a marine traffic issue

and by the way I magically started transmitting today immediately I turned it on, my friendly coastguard could see me (and he couldn’t yesterday ) and yes,..so can marine traffic

I will try MikeCC suggestion

 

[jwfrary]

Have you checked the transponders always getting a GPS position, if it doesn't then it will stop transmitting!

 

[Daverw]

I’ve just had a similar issue, found bad center core connection that raised swr and reduced power and also broken outer shield in GPS coax leading to poor intermittent GPS receive, when GPS poor AIS stopped transmitting, soldered antenna, cut out damaged coax and now back normal

 

[Bathdave]

I’ve just had a similar issue, found bad center core connection that raised swr and reduced power and also broken outer shield in GPS coax leading to poor intermittent GPS receive, when GPS poor AIS stopped transmitting, soldered antenna, cut out damaged coax and now back normal

Have you checked the transponders always getting a GPS position, if it doesn't then it will stop transmitting!

Thanks both ...this isn’t something I had focussed on, I will review this

 

[greeny]

whilst I appreciate any input, With respect I think you’re missing the point


With respect - this is what you said -
"I am increasingly thinking an aerial issue, but my radio checks with CG are fine

my next step is to borrow an emrgency VHF aerial and attach it and see if that makes any difference. "

read post 7 - what did I suggest?
Do as you please - your choice

 

[lustyd]

It's likely that the unit can receive very local stuff without an antenna so sometimes these tests aren't that useful. Similarly, with the CG they have huge antennas all over the place so that's not a good sign your set is working, try a smaller target like a marina or coast watch station. VHF at 25W will often work on a duff cable enough to look fine, but as others have said the inside of that cable is very probably powder rather than metal at this point. You could try replacing all of the connectors before changing the cable as an easy option - don't forget the join at the mast foot, often hidden above the ceiling panels.
Everything you describe here though screams duff cabling. If it were me I'd replace the cable regardless of testing at this point, despite the effort involved. Presumably you fitted AIS as a safety feature, so it ought to be a priority.

 

[Bathdave]

It's likely that the unit can receive very local stuff without an antenna so sometimes these tests aren't that useful. Similarly, with the CG they have huge antennas all over the place so that's not a good sign your set is working, try a smaller target like a marina or coast watch station. VHF at 25W will often work on a duff cable enough to look fine, but as others have said the inside of that cable is very probably powder rather than metal at this point. You could try replacing all of the connectors before changing the cable as an easy option - don't forget the join at the mast foot, often hidden above the ceiling panels.
Everything you describe here though screams duff cabling. If it were me I'd replace the cable regardless of testing at this point, despite the effort involved. Presumably you fitted AIS as a safety feature, so it ought to be a priority.

Thanks LustyD

the problem with an intermittent problem is, when it’s working it’s working and it’s hard to isolate the problem..

i have tried most of the suggestions on here...it wasn’t transmitting on Monday and I was not able to get an emergency aerial yet to try to see if that solved it

by Tuesday, and ever since, it has been transmitting and receiving fine.

I picked up the point made by MikeCC and downloaded ProAIS and Connected it up, but it’s all showing hunky dory

I picked up your point that the unit may pick up stuff without an aerial (which hadn’t occurred to me) so I disconnected aerial while unit was working okay and realised that I could still see boats close by despite the absence but ones further away dropped off.

so I’m pretty confident that it is an aerial cable or its connectors so I will check and replace all those.

 

[Daverw]

Is it possible to temporarily use your vhf antenna to test fir a day or so. This will eliminate one thing, you may need a pl259 to TNC adapter though. When you used ProAis did it report a good SWR

 

[Bathdave]

Is it possible to temporarily use your vhf antenna to test fir a day or so. This will eliminate one thing, you may need a pl259 to TNC adapter though. When you used ProAis did it report a good SWR

Thanks ...I’m not sure I really understand your first point

re the SWR the figure I got on ProAis was 1.6:1 ..I have no idea what this means but a quick review via google gave me the impression this was a ‘good’ result

 

[Daverw]

What I meant was if you are not sure about the AIS antenna you could connect your vhf one to give it a try, SWR of 1.6:1 is ok, 1:1 is lowest but you will never get this in the real world, Ive tuned mine to 1.2:1 but I have the gear to do it.
just to add that I found the swr reported on ProAis a bit out

 

[Bathdave]

What I meant was if you are not sure about the AIS antenna you could connect your vhf one to give it a try, SWR of 1.6:1 is ok, 1:1 is lowest but you will never get this in the real world, Ive tuned mine to 1.2:1 but I have the gear to do it.
just to add that I found the swr reported on ProAis a bit out

Ok thanks now I understand ...I explained earlier in the thread I have one masttop aerial and a signal splitter

i plan to get an emergency VHF aerial and try that but while everything is working on it doesn’t really achieve or prove anything ..I need it to stop working to see if an aerial change fixes it

the fact that even when my AIs is not working but my radio IS has deflected me from thinking the aerial is the problem but the fact the transmission power of the radio is much higher than the AiS transmitter has been picked out by someone in this thread

 

[Daverw]

Yes I understand the splitter fitted that is more of a reason to connect direct and see if it’s the splitter not helping. They do add to signal loss and can hide issues, of course you cannot use the vhf whilst testing.