Coast Guard Safety Alert: LED lights interfere with VHF & AIS radios

[svmobert]

Originally Posted by sasirles

Is the failure intermittent? Is it partial or complete? My VHF and AIS appear to be operating correctly, but maybe they aren't and I have just not recognized it.

If you read the CG docs on it. It's basically a loss of signal strength. The level of continuous noise received by the radio at all times that the LED is on, and the radio (either automatically, or manually via squelch) is set to stay quiet, only bypass the squelch for signals stronger than that noise level. This means that as the noise level increases, your RX range decreases. And that noise may also cause interference in your transmission so others have a harder time hearing you.

So it's not a complete failure, it's reduced performance.

[Cpt Pat]

Originally Posted by sasirles

Is the failure intermittent? Is it partial or complete? My VHF and AIS appear to be operating correctly, but maybe they aren't and I have just not recognized it.

The production of RFI from the lamps could change with supply voltage because the duty cycle on the internal switching power supplies changes. But I'd say, intuitively and without hard backup evidence, that generally it's a "go no-go" situation. They are either bad or good.

[leftbrainstuff]

You want to look for EMI and EMC. The I looks at interference of the device to other devices. The C for compatibility looks at resistance to interference.

We don't put anything electronic on our boat that isn't adequately certified for both EMC and EMI.

It's getting harder to get certified products. We've had a few devices we've returned. Don't expect orgs like the USCG to keep up with the certification listing of new products.

Now that nearly all Mil Specs have been cancelled basically any vendor can sell anything and certify it with anyone. Even comms equipment, like the Chinese HF devicea slip thru the FCC.

Also don't forget the wider system impacts. Don't route comms wiring with power leads for example. Alao don't use anything intended for residential usage. Light dimmers for example.

[Cpt Pat]

Originally Posted by Sea-TechSystems

If you read the CG docs on it. It's basically a loss of signal strength. The level of continuous noise received by the radio at all times that the LED is on, and the radio (either automatically, or manually via squelch) is set to stay quiet, only bypass the squelch for signals stronger than that noise level. This means that as the noise level increases, your RX range decreases. And that noise may also cause interference in your transmission so others have a harder time hearing you.

So it's not a complete failure, it's reduced performance.

I had an LED deck light on my boat - for a very short time before I ripped it out and sent it back - that wiped out reception of very nearby transmitters (the Harbor Master 300 feet away), and it even wiped out FM broadcast stations transmitting with 100,000 watts 20 miles away. My AIS didn't receive boats with Class B AIS transponders that were 0.5 nm away, and my own Class B transponder using carrier-sense (CSTDMA) protocol stopped transmitting because it couldn't find an "unused" time slot.

I'd call that a complete failure.

[Cpt Pat]

Originally Posted by Sea-TechSystems

And that noise may also cause interference in your transmission so others have a harder time hearing you.

A noisy LED shouldn't have any impact on your ability to transmit - unless it's so noisy that it wipes out reception miles away at the receiver - which is very unlikely.

Originally Posted by leftbrainstuff

Also don't forget the wider system impacts. Don't route comms wiring with power leads for example.

All good advice in your full post. Unfortunately, in some cases, that separation is impossible to achieve. For instance, when power for a masthead light (tri-color, anchor light, steaming light) has to be passed inside a sail mast along with the antenna coax cable. Coax cables don't have 100% shielding, and RF on the shield can induce a signal at the antenna and the radio. One could run the coax outside the mast, but I've never seen it done.

What's really daunting about this problem is that there are no fully effective countermeasures besides replacing the LED with one that doesn't spew RF in the VHF band. Shielding and suppression will help, but its only mitigation - not elimination.

Some people may accept LEDs that emit just a small amount of interference, but before they accept a "slightly noisy" LED, they need to test across the entire marine VHF band. The interference is often worse in some parts of the band than others.

[Captain Anthony]

Thank you for this information. I will be replacing all of my old incandescent bulbs with LED's this spring. I intend to keep following this thread.

[Cpt Pat]

Originally Posted by Chotu

The coax for the VHF antenna cable is enough?

No. The noise will be picked up by the antenna and sent down the coax just like a desired signal.

[Cpt Pat]

Originally Posted by astokel

Here's a video that explains how you can test to see if your LEDs are bad.

Excellent video. Thanks for sharing that. One caveat: the newer radios that have phase-locked loop (PLL) receivers will not de-squelch from random noise. Instead, you will hear weak signals vanish or be covered by noise. Newer Standard Horizon radios behave this way - which is usually desirable because you don't have to continually readjust the squelch in areas of random noise.

Using a handheld radio though is a great way to home in and identify which LED in a group is bad (or worst).

[roland stockham]

It is not just LED lights. With so many electrical devices on boats these days the potential for radio interference is high. Check it every season. Don't assume it is OK because you bought 'reputable' US devices, I have an LED spot on the truck that that is made by a top US manufacturer that would be unacceptably noisy on a boat.

[Cpt Pat]

Originally Posted by brownr377

In europe marine electronic equipment has an extremely low EMI limit in the VHF band, no such regulation exists in the US.

Yes. I feel that is the root of the problem.

[roland stockham]

Originally Posted by brownr377
In europe marine electronic equipment has an extremely low EMI limit in the VHF band, no such regulation exists in the US.


That explains why I have no problem, all my stuff is European certified. My test is to tune to a low power AM station then turn on everything and see if I get any noise. Never thought to try it on FM though. On thing I have found is that having a separate radio ground that is only used for that (e.g. grounds radio chassis and aerials only) and a separate battery for the electronics cuts radio noise a lot.

[Lost Horizons]

Originally Posted by Gypsyjon

There are plenty of LED bulbs available that do not release RF.

Check out Dr. LED site. They are expensive but work.

I had a Dr. LED product in the anchor light that generated RF noise. Yes, it was expensive junk.

[john61ct]

Originally Posted by roland stockham

One thing I have found is that having a separate radio ground that is only used for that (e.g. grounds radio chassis and aerials only)

Well the one and only true ground on a boat is the one connected to the water right?

So by "another separate" one, you mean sharing a common negative return isolated from the previous "true ground"?

Would that be called a floating ground?

> That explains why I have no problem, all my stuff is European certified.
For USians then, easy solution is buying our LEDs from European marine-oriented sources?

I assume not necessary for the radio gear, right?

[Cpt Pat]

Originally Posted by john61ct

I assume not necessary for the radio gear, right?

With regard to this specific issue, you are correct. Generally, FCC certification is pretty solid on radio gear. I worked with a (now defunct) company that would send a "lab queen" to the testing lab, and then market a cheaper version. Products can slip through the cracks. They thought the FCC would never retest a production version of the product. They were wrong. That's why they are now defunct.

It's sad that our lack of regulations in the US may encourage a "Buy European" result. But the US manufacturers are free to get CE certification.

I would be very suspicious of any brand of marine LED that didn't obtain that certification.

[Cpt Pat]

Originally Posted by Lost Horizons

I had a Dr. LED product in the anchor light that generated RF noise. Yes, it was expensive junk.

Please, if you have the time and inclination, inform the USCG of your issue with the Dr. LED product. It'll be a service to all mariners. https://www.navcen.uscg.gov/?pageName=contactUs