LED lighting is increasingly popular in the commercial sector, especially for nighttime fishing. But those lights —as well as LEDs used for navigation, searchlights and interior lighting — can adversely affect VHF frequencies as well as AIS and DSC signals, according to the U.S. Coast Guard.
“Radio frequency interference caused by these LED lamps was found to create potential safety hazards,” said a Coast Guard Marine Safety Alert released in August.
In one port, the maritime rescue coordination center wasn’t able to contact a ship by VHF radio. The same vessel had poor AIS reception.
“LED lighting installed near VHF antennas has also shown to compound the reception,” read the alert.
The recently released Marine Electronics Journal’s November/December issue said the Global Maritime Distress and Safety System task force recently began investigating the LED issue “but so far has identified no solutions.”
For the same story, the journal spoke with Brian Rodgers, president of Shadow-Caster, a manufacturer of LED lighting in Dunedin, Fla., about the issue.
He said the problem is with “some of the ‘switching’ power supplies that are used inside these lighting fixtures. LED lighting fixtures that use linear and passive-type power supplies do not create any more noise than a traditional incandescent bulb. However, ‘switching’ power supplies, which literally switch to convert power at a very fast rate and cause electromagnetic interference in the AM and VHF ranges, are the culprit here.”
Rodgers adds there are standards for measuring and controlling EMI and the marine industry needs to enforce those standards for lighting products with “switching” power supplies.
You don’t always know if you are getting LED interference on a VHF radio — if you are, there’s also probably AIS interference. However, the Coast Guard’s Marine Safety Alert has a short section describing how to test for LED interference.
It’s worth checking out first before tossing those LED lights overboard.