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.