Coast Guard Warns of Radio Interference from LEDs

Posted by Darrell Nicholson at 06:33AM - Comments: (6)


LED lightsBack in 2010, Practical Sailor and others raised the alert that a conversion to LED navigation lights can have some unintended consequences, including distorted color shifts (see PS January 2016 “USCG Issues Alert on Uncertified Nav Lights” and PS October 2017  “Converting an Anchor Light to a Tricolor Light” ). And we’ve long been concerned about LED lights, both interior and exterior, interfering with VHF and AIS radio transmissions (see PS February 2010 “Practical Sailor Tracks Down the Best LED Tri-color Light” see PS June 2014, “LED Interior Lights Part 2”). 

The problem with radio interference has recently gotten the attention of the U.S. Coast Guard, which released the following Marine Safety Alert on August 15, 2018. 

“The U.S. Coast Guard has received reports from crews, ship owners, inspectors and other mariners regarding poor reception on VHF frequencies used for radiotelephone, digital selective calling (DSC) and automatic identification systems (AIS) when in the vicinity of light emitting diode (LED) lighting on-board ships (e.g., navigation lights, searchlights and floodlights, interior and exterior lights, adornment).

"Radio frequency interference caused by these LED lamps were found to create potential safety hazards. For example, the maritime rescue coordination center in one port was unable to contact a ship involved in a traffic separation scheme incident by VHF radio. That ship also experienced very poor AIS reception. Other ships in different ports have experienced degradation of the VHF receivers, including AIS, caused by their LED navigation lights. LED lighting installed near VHF antennas has also shown to compound the reception.

"Strong radio interference from LED sources may not be immediately evident to maritime radio users. Nonetheless, it may be possible to test for the presence of LED interference by using the following procedures:

1. Turn off LED light(s).

2. Tune the VHF radio to a quiet channel (e.g. Ch. 13).

3. Adjust the VHF radio’s squelch control until the radio outputs audio noise.

4. Re-adjust the VHF radio’s squelch control until the audio noise is quiet, only slightly above the noise threshold.

5. Turn on the LED light(s).

-- If the radio now outputs audio noise, then the LED lights have raised the noise floor. (Noise floor is generally the amount of interfering signals / static received beyond the specific signal or channel being monitored.)

-- If the radio does not output audio noise, then the LED lights have not raised the noise floor.

“If the noise floor is found to have been raised, then it is likely that both shipboard VHF marine radio and AIS reception are being degraded by LED lighting.

"In order to determine the full impact of this interference, the Coast Guard requests those experiencing this problem to report their experiences to Coast Guard Navigation Center. Select “Maritime Telecommunications” on the subject drop down list, click "Contact Us" in the menu bar then briefly describe the make and model of LED lighting and radios effected, distance from lighting to antennas and radios effected, and any other information that may help understand the scope of the problem.

“This Safety Alert is provided for informational purposes only and does not relieve any domestic or international safety, operational, or material requirement. Developed by the U.S. Coast Guard, Spectrum Management and Telecommunications Policy Division. Distributed by the Office of Investigations and Analysis. Questions may be sent to

The Coast Guard’s complete notice, Safety Alert 13-18 can be found along with other Safety Alerts at the "Safety Alerts and Lessons Learned" web page at the US Coast Guard website. 

Comments (6)

I understand your idea behind the testing, but you didn't finish and have given people a black or white conclusion.

Okay, VHF 13, squelch turned down as low as possible while preventing noise. You turn on the LED and you hear noise. How much noise? Are we talking (1) notch on the squelch? Or are we talking having to turn up the squelch all the way?

I manage sailboat races professionally and spend a lot of time on the water. I am on the radio constantly for up to 6 hours at a time when managing races. There are a lot of things not on my boat that cause me to have to increase the squelch threshold. Some a little and some a lot.

I also worked at West Marine for 14 years and you'd be amazed at what I saw people do, which leads me to the equipment used like the fact that you didn't mention anything about the VHF cable. Did you test using RG-58CU, RG-8X or RG-213? Or...did yo test with RG-59U? You'd be surprised at the number of people who think they can use RG-59U cable. How old is the cable? What about the radio? New high end radio or 30 year old low end radio? The list goes on.

Next, are we talking in a bay where anyone you'd want to hear is within a few miles? Or are we talking offshore where you'd be pushing the limits of the VHF bandwidth?

My point is, so there may be some noise, but at what level does this additional noise become a problem? Is it worse than other factors that reduce the effectiveness of a vessel's VHF or AIS system? Even if there is perceptible noise on the VHF it doesn't mean there will automatically be a reduction of the AIS performance, but you didn't mention that. There is so much to be considered and you didn't mention most of it.

In reality each boater must test for themselves the amount of noise and how it affects their VHF and AIS systems to determine if it is a problem on their vessel or not.

I know the boating public from my perspective of 14 years in marine retail I can bet you that most who read your article and can pick up ANY perceptible noise will be rushing out to find the latest and greatest when it might be unnecessary.

Posted by: jzarwell | September 7, 2018 11:41 AM    Report this comment

"My generator and even the alternator on my engine caused interference on MW SSB. Jon. KF6FKF"

The rf from your alternator and generator is likely an unfiltered component of the DC supply side and John; as a Ham Radio operator you should well understand the causes of spark emitted interference and how a few well placed toroids and capacitors to ground on the power side of the cicuit generally solves that problem.

Comparing Generator and Alternator supply noise is a non-sequitur.

Posted by: rav555 | August 30, 2018 9:46 AM    Report this comment

What this piece does not comment on is the unintentional RF interference is NOT radiated by the LED semi-conductor but rather the frequency conversion electronics that DRIVE the diode. The FCC calls this a Unintentional Emitted Interference.

What you want to purchase are FCC Part 15 Certified devices. If in fact you have a device that interferes with your RF device then the FCC must be notified so they can enforce their regulation with heavy fines or outright embargoes on importation.

The FCC takes Unintentional and Intentional RF interference EXTREMELY SERIOUSLY.

Google Intertek + FCC Part 15.

While the US Coast Guard is certainly the authority regarding Maritime equipment. The FCC has jurisdiction over ALL RF emitting devices whether they are intentional emitters or unintentional emitters; this Regulatory Authority extends also to ALL RF Emitting devices including and not limited, computers, TV sets, microwave ovens, LED LIGHTS, HF, VHF, UHF Transceivers, mobile phones, WIFI and bluetooth devices, garage door openers, etc, etc, etc ad infinitum.

And lastly, if you as a consumer place into service an RF emitter and that emitter interferes with Licensed and regualated Radio servcies then YOU as a consumer are in violation of FCC Part 15. While it is likely you will not be fined, you would be well advised to remove those devices and return them to the manufacturer as ILLEGAL RF devices.

You will notice that on the back of EVERY RF emitter in your home, auto or boat there is an FCC Type certification sticker. RF emitters that do not have this Certification are illegal in the United States.

Google FCC Declaration of Conformity Logo and you will see that an FC (inscribed sencond C) is shown. Look on the bottom of your laptop and you will see the same Logo along with EU and other Certifications.

As the consumer it is your responsibility to purchase conforming products.

Posted by: rav555 | August 30, 2018 9:41 AM    Report this comment

My generator and even the alternator on my engine caused interference on MW SSB. Jon. KF6FKF

Posted by: | August 30, 2018 9:37 AM    Report this comment

1) Excellent suggestion!
2) In many locations SeaTow offers automated VHF radio checks on either ch 26 or 27 or 28. Jon.
3) I recently discovered that USCG no longer monitors 2182 Kc. Jon KF6FKF

Posted by: | August 30, 2018 9:34 AM    Report this comment

I bought a #51 anchor light from Amazon and several IMTRA Marine Lighting
brand cabin lights. Without exception, any led product marked as 10-30 vdc caused significant RFI on all frequencies between AM broadcast and VHF. It took several orders to find simple resistor ballasted led lamps.
Anchoring next to someone that has switching type led lighting makes HF 2-30 MHz unusable. Pure sine wave power inverters are probably worse sources of RFI (just like some marine led lighting), except significantly more power.

Posted by: wa9vez | August 30, 2018 9:29 AM    Report this comment

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