[TG] [TG11] AIS 650 stops displaying targets

[timgoodyear]

I have an AIS 650 interfaced to an es127 via SeatalkNG and to a Standard Horizon GX2000 via NMEA0183. Both used to work very well, but I have seen numerous occasions in the last few weeks (coming from Panama to Florida) where all AIS targets disappear from display on both devices and don't reappear for several minutes or hours. The boat's AIS data continues to be transmitted during that time (as reported by other vessels). Any ideas on how to fully diagnose / correct the issue, or is it time to replace the unit?

MFD and AIS are on latest software.

Connecting to the AIS 650 with ProAIS2 is normally fine, but I get "USB Device not recognized" on the PC when I plug in the USB cord when it is not displaying targets.

Cycling power on the AIS unit generally causes targets to be displayed again when it powers up.

Thank you,

Tim

Tim Goodyear
SV Mojito
Currently Key West, FL

[Tom - Raymarine - Moderator]

Hello Tim,

Some questions:

• Does the AIS appear in the eS127's SeatalkNG device list (Home > Setup > Maintenance > Diagnostics > Select Device), at the time the problem is happening?
• What does the AIS's LED show, at the time the problem occurs?
• Does the AIS work with the PC over USB the rest of the time?
• If you disconnect the STNG, does the NMEA0183 work?
  

The AIS is designed to be connected over either SeatalkNG or NMEA0183 but not both at the same time, so it's possible - especially if you have two-way NMEA0183 - that this is causing the AIS's software to crash, or similar.
Alternatively, perhaps you have a power-supply issue where the AIS's supply voltage is dipping when it tries to transmit and this is causing an internal networking failure.

It's not a common issue I've come across personally, so this is a bit speculative.

Regards,
Tom

[timgoodyear]

Hi Tom,

Thank you for the response - I had a chance to try out some things on the way from FL to SC.

<Does the AIS appear in the eS127's SeatalkNG device list>
- Yes, it appears in the device list, and the diagnostics information looks fine (if minimal)
<What does the AIS's LED show, at the time the problem occurs?>
- I still need to work on this one; the AIS is installed behind a panel that is a pain to remove when offshore. I will relocate the AIS unit to be accessible before we set off on another offshore leg on Wednesday
<Does the AIS work with the PC over USB the rest of the time?>
- Yes, no problems with connecting at other times
<If you disconnect the STNG, does the NMEA0183 work?>
Per the second question, I can't easily make that happen at present, but will devise an environment where I can later this week

The AIS is connected over SeatalkNG and is sending data over 0183 to a Standard Horizon GX2000 for display. It isn't connected to receive 0183 data. This setup had been working fine for two years, but is no longer reliable. I see the issue when motoring (battery voltage at 13.6V or above) or sailing (typically 12.4V minimum after an overnight passage). I'll try the voltage measurement as well.

My only other thought is an intermittent antenna issue, but every time I test with ProAIS2, the SWR is good, and I don't have receive / transmit problems with the VHF using the same antenna. I have a second antenna on a stern arch - obviously with less overall range than masthead. It seems to be worse all round (range and clarity) than the masthead.

Any other thoughts / diagnosis tips?

Many thanks,

Tim

[Tom - Raymarine - Moderator]

Hello Tim,

The only other thing I can think to suggest at the moment is that you record some of the NMEA2000 traffic during an instance of the problem, to see whether it's communicating at all. We can read the log for you if you send it in.

Other than that, the failure of the AIS to be correctly detected over USB at the time the problem occurs suggests an internal fault, if it's not a supply problem - remembering that supply reaching the AIS may be a lot lower than at the batteries or distribution panel.

One other possibility - it could conceivably be a grounding problem, if either the Standard Horizon or the PC (PC's power supply from an invertor?) weren't isolated.

Regards,
Tom

[timgoodyear]

Hi Tom,

I have the AIS unit exposed now, with a second VHF antenna handy to swap as a test, and the SeatalkNG and NMEA0183 connections available. I will check lights etc on our next passage.

I will record the AIS traffic on the es127. Is there any point in recording the ProAIS2 serial data if I leave that connected?

ProAIS2 is saying the AIS power supply voltage is 13.5V when at the dock; the battery charger shows 13.5V, the battery monitor 13.48V, with the rest of the instruments on (but not the Autopilot that's on a separate breaker). SWR is reported at 1.7.

The PC is operating on battery when we're offshore - I will check the RF Ground on the VHF.

Thanks for the pointers - I will let you know what we see.

Regards,

Tim

[timgoodyear]

I had a lot of time to think about this in the Gulf Stream recently. My biggest fear with the issue was not having AIS at night, but it always seemed to work OK somehow. So... I tried turning the solar controllers off, and sure enough more targets appeared and I was able to see full details of ships earlier. I tried it a few times, and solar appears to bethe culprit.

The controllers are Victron Smart Solar MPPt controllers. They are located far from the VHF and antenna, but the wires from the solar panels to the controllers run past (2’) from the splitter and AIS650, and in the same conduit as the antenna cable for about 15’.

I will re-route the cabling from the PV panels away from the VHF antenna, but was wondering whether you had any other thoughts on this? Could the MPPT controllers themselves be interfering from 12’ away?

Many thanks,

Tim

[Tom - Raymarine - Moderator]

Hello Tim,

The output from the controllers may well be a PWM signal rather flat DC voltage, which could be expected to cause interference in poorly-shielded cables running close together depending on the frequency, amplitude etc., but I wouldn't expect this on the upstream (PV) side of the controllers. Similarly though, I would not expect good-quality controllers - and I have no reason at all to doubt Victron products, I believe they are certainly good-quality - to emit any problematic radiated noise, especially that would be strong enough to cause problems at that sort of range.

I've heard of excessive noise being picked up on antenna cabling where there was a break in the shielding, even when other devices around weren't emitting an abnormal amount of noise, but I think that in this case there's a good chance that you have a ground loop. There is good information on ground loops at:

https://en.wikipedia.org/wiki/Ground_loop_(electricity) (introductory)
https://web.mit.edu/jhawk/tmp/p/EST016_G...andout.pdf (detailed)

Neither of these are aimed at boats, and there are many, many resources out there, but you might have a ground loop in your system if, for example, the your AIS antenna's shield is connected, at the mounting point, to some metalwork which is also connected to the solar system. The antenna's shield might therefore end up providing an unintentional path back to supply negative or a sea earth. This is just an example, but I'd suggest one of the following:
- doing some reading and then taking a good look at the installation and measuring to see what has continuity (non-infinite resistance) to what, starting with the antenna's mounting
- testing by replacement: trying a different power cable path for the chargers (cable run loosely outside the boat), emergency VHF antenna mounted somewhere else with a different cable run, temporarily moving the AIS off the main vessel supply onto a standalone battery (no return path for noise that way) etc.
- next time you're somewhere you have the chance, engaging a marine electronics expert to look over the system.
Just don't start disconnecting or connecting grounding points unless you really know what you are doing. There are lots of different types of grounding systems and some of them are there for either safety (AC ground, lightning ground) or corrosion-protection.

Regards,
Tom

Regards,
Tom

[timgoodyear]

Hi Tom,

Thank you for the response - I will read up your references on ground loops and re-examine the system - all good ideas. I have come across others with issues with Victron solar controllers - link to a thread on their forum below, but it didn't always have this issue, so I'm sure it is something on the installation.

https://community.victronenergy.com/ques...ment-22700

Not that it's helped me too much on this issue yet, but I am ABYC Electrical / NMEA Installer certified.

Thanks!

Tim

[Tom - Raymarine - Moderator]

Hello Tim,

That's interesting.
Since you're in the business: what I would be advising one of our technical dealers here in Australia to do, if they came to us with this problem, is suggesting that they put their portable oscilloscope on the power supply (this isn't a joke, we now push all technical service dealers in Australia to carry a low-cost oscilloscope in their toolkit: I use a Bitscope BS05 with x10 or x100 probes), but more importantly - since the feeling seems to be that the problem is airbourne RF interference - to use a low-cost RTL-SDR spectrum analyser to check for radio interference at 162MHz.

RTL-SDR is our standard tool for looking at all sorts of RF problems. It's a combination of very low-cost USB hardware (~$25), a VHF/AIS antenna and free or very cheap computer software (Win/Mac/Linux/Android but not iOS) to 'listen in' to the same band that your AIS is listening to (~162MHz.) You should be able to run the SDR with the solar system off, then power it on and see whether there's a big change in background noise level. You should be able to see received AIS messages as well as the noise. SDR is an amazing tool for this sort of thing, if you put in a little effort to getting to grips with what it's showing you.

There's a good bit of background info on https://www.rtl-sdr.com/about-rtl-sdr/, you can get suitable low-cost dongles from Ebay and the like.

Attached is a screenshot from my Android phone using the low-cost RF Analyzer app, showing a sequence of AIS signals on the two channels either side of 162MHz in the middle, an FM radio broadcast on the far left and a VHF radio call (a taxi company) on the right. In between all this is just background noise. In your situation i'd expect you to see AIS signals like these when the solar wasn't running and then the AIS transmissions being lost in a higher background noise level when they were. If you get the chance to do this, I'd be interested to see some images.

Good luck with it,
Tom

[Kr7]

I have similar situation with AIS 700 and Axiom7. But i think it started after i upgrade firmware to current version - 1.06.02.

When i start to sail i see lot of targets, in time that i sail i see they are dissappearing. After i connect laptop with ProAIS and push "Connect" button, targets are back in a moment (1-2 minutes). After i wait - they are start to dissapearing again.

Here are two pictures of my ploter - 18:23 and 18:30 after i have connected laptop and click 'connect'.