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USCG Alert: LED lights may interfere with VHF/AIS


By DariaBlackwell - 18 Aug 2018

The U.S. Coast Guard is alerting mariners to the potential for LED lights to interfere with the reception of marine VHF radios and AIS receivers. Issued yesterday, Marine Safety Alert 13-18 notes an incident where a ship could not be hailed by VHF radio and other incidents where ships reported very poor AIS or VHF radio reception due to LED navigation lights.

Fortunately there is a simple test that may tell you if LED lights on your vessel are causing interference. From the Marine Safety Alert:
- Turn off LED light(s).
- Tune the VHF radio to a quiet channel (e.g. Ch. 13).
- Adjust the VHF radio’s squelch control until the radio outputs audio noise.
- Re-adjust the VHF radio’s squelch control until the audio noise is quiet, only slightly above the noise threshold.
- 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.

The Coast Guard want to know more about this problem and if you experience radio interference from LED lights on your boat, the request that you notify the Coast Guard Navigation Center. Learn more by reading Marine Safety Alert 13-18.
By DariaBlackwell - 18 Aug 2018

More on the subject here: http://forum.gcaptain.com/t/led-lights-interfering-with-vhf-dsc-ais/48943/7
By Dick - 18 Aug 2018

Hi Daria,
I am not sure what the USCG are referring to, but it sounds very like the report and discussion on the Attainable Adventures Cruising’s web site back in 2012. The report was on Lopo light’s LED tricolour and its interference with VHF communication. The reporter went through 4 Lopo lights in 5 years with Lopo light trying to solve the interference problem and failing: the sailor then went to another brand of tricolour when unable to solve the problem (if memory serves). Other discussants reported similar problems. Also (from memory) other LED tricolour lights did not seem to be reporting RF interference. My AquaSignal Series 40 LED tricolour does not cause RF interference on Alchemy.
Did the USCG report the brand of LED lights causing interference: or indicate that it was a few brands?
As an aside, I noticed that, although there was a number of reports about Lopo lights causing problems over the years and Lopo light acknowledged the problem and suggested remedies yet,I saw no mention of this fact in any of the commercial magazines that cover our sport/recreation. To me this is an unconscionable kowtowing to their advertising world and a complete abdication of the media’s responsibility to report and to protect its readers from shoddy goods and practices.
My best, Dick Stevenson, s/v Alchemy
By simoncurrin - 19 Aug 2018

We have experienced minor interference from the saloon LED’s and in particular from the first generation ones from around 2006. Since then we have been replacing them with modern ones that cause much less of a problem.

Dick I am surprised any Lopolight lasted long enough to cause interference! We switched over years ago as repeated Lopos - all readily replaced free of charge - failed to last a season.