Let us enlighten
you about LED lighting!
Potential interference of VHF-FM Radio and AIS Reception.
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
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:
off LED light(s).
the VHF radio to a quiet channel (e.g. Ch. 13).
the VHF radio's squelch control until the radio outputs audio noise.
the VHF radio's squelch control until the audio noise is quiet, only slightly
above the noise threshold.
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.)
the radio does not output audio noise, then the LED lights have not raised the
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, 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.
My heart sank when this notice crossed my desk. We had just finished replacing all of our mast lights with LED lighting; even adding anchor and deck lights to our Mizzen. We have two fixed mount VHF units and AIS, and installed an antenna on each mast – all at not inconsiderable expense. The good news: when doing the above test we got no noise despite turning everything on. The brand, selected for us by Astilleros Lagos in Vigo, Spain was Aqua Signal.
SAFETY ALERT - LED LIGHTING INTERFERENCE VHF FREQUENCIES
see original alert here
United States Coast Guard
Inspections and Compliance Directorate
August 15, 2018
Safety Alert 13-18
Note: It is neither stated nor implied that any of the above products display the above mentioned issues