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Old 09-07-2013, 18:01   #1
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EMF Interference affecting Chartplotter signal

I have had fitted a D400 wind generator and two 80w solar panels.
I took my Catalina 445 out for a trip around the bay and noticed the chart plotter (Furuno Navnet 3D) picture shifting wildly, initially I guessed it was loss of GPS signal. This has never happened in the two years prior.
I have written to the UK manufacturer of the D400 and they came back with a possible shielding problem.
The suggestion is the cabling from the D400 and/or solar panels by emitting EMF is affecting the data cable from the Chart plotter.
The shielding suggested was aluminium pipe grounded to the ship.

Has anyone got a view on this?
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Old 09-07-2013, 19:46   #2
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Re: EMF Interference affecting Chartplotter signal

I don't think your solar panels are contributing - they are just passing DC current. I don't know enough about the D400 to say where the EMI may be occurring.

Have you tried putting ferrites on the power leads of the Furuno and D400? Also, the power cable for the Furuno has a shield that should be tied to ground at one end.

I don't think it is a problem with the Furuno - it does sound more like a GPS problem. When it is happening, what does the GPS page on the Furuno tell you about the satellite number and signal quality and the HDOP?

Mark
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Old 09-07-2013, 19:58   #3
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Re: EMF Interference affecting Chartplotter signal

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Originally Posted by colemj View Post
I don't think your solar panels are contributing - they are just passing DC current. I don't know enough about the D400 to say where the EMI may be occurring.

Have you tried putting ferrites on the power leads of the Furuno and D400? Also, the power cable for the Furuno has a shield that should be tied to ground at one end.

I don't think it is a problem with the Furuno - it does sound more like a GPS problem. When it is happening, what does the GPS page on the Furuno tell you about the satellite number and signal quality and the HDOP?

Mark
Most solar arrays use a switching regulator to prevent overcharging. The regulator could be an interference source. Connecting the regulator close to the battery bank could help.

There have been situations where a reflection off helicopter rotor blades have disrupted digital radio transmissions. You might repeat the test with the wind generator stopped.
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Old 09-07-2013, 20:05   #4
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Re: EMF Interference affecting Chartplotter signal

Yes, the controller could be putting out RFI, but I can almost guarantee that it would not be interfering with the Furuno. Not only are controllers generally mounted a good distance away from chartplotters, but the frequencies are wrong for interference.

Easiest thing to do would be disconnect the solar and see if the problem still exists.

I'm still betting on something happening with the GPS. Either interference or the wind gen blocking part of its visible sky. The Furuno GPS monitor will tell if something is happening there.

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Old 09-07-2013, 20:14   #5
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Re: EMF Interference affecting Chartplotter signal

Was the wind blowing? If you shut down the wind generator does the picture change? If no current is flowing would there be any EMF? This is sometimes the kind of stuff you get with exposed terminal boards and poorly spliced wires.
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Old 09-07-2013, 20:39   #6
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Re: EMF Interference affecting Chartplotter signal

My VHF's, handheld and fixed, were not usable and jammed by RFI from the solar panel controller. The RFI was bad enough that any VHF within 100' was jammed. Replaced the charge controller and the problem has gone away. As bad as the RFI was, I never saw any problem on my Standard Horizon CP3000 chart plotter.
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Old 09-07-2013, 21:41   #7
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Re: EMF Interference affecting Chartplotter signal

If that windgen set is new I would contact the manufacturer, tell them that Furuno thinks it is putting out RFI, see what they have to say. If they can't cure the problem simply and quickly, I'd send the whole kit back, if there was any return period on it. RFI is nonsense today, manufacturers often allow it simply because it would cost more to "do it right" and prevent it at the source.

Whether it is the windgen or the solar controller (if there is a controller?) put the burden back on that supplier, if they can't solve it fast, send it back.
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Old 09-07-2013, 22:39   #8
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Re: EMF Interference affecting Chartplotter signal

Thank You all for those excellent suggestions.
i will go through a troubleshooting process by isolating components and see what transpires. standby for an update in a few days.
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