[TG] [TG11] AIS 650 stops displaying targets

[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