[Public-List] Fwd: led masthead light

[Joseph Balderson]

A friend commented on the led/vhf/ais interference issue


---------- Forwarded message ---------
From: Eric Crawford <eericcrawford at gmail.com>
Date: Mon, Aug 27, 2018, 8:01 AM
Subject: Re: led masthead light
To: Joe Balderson <joebinc at gmail.com>


Got this from the CCA the other day describes how to test for it.

[image: Safety Alert: LED lights may interfere with VHF-FM and AIS
reception]
<https://facebook.us19.list-manage.com/track/click?u=525f1e4a25cf3f056ef7d0926&id=2318b152dd&e=9866bdbb6a>

AUGUST 16, 2018 — LED lighting may offer energy savings advantages, but a
new U.S. Coast Guard Safety Alert (13-18) warns that it can potentially
interfere with VHF-FM radio and AIS reception.

The Safety Alert says the 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 was 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. Readjust 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.)
   6. If the radio does not output audio noise, then the LED lights have
   not raised the noise floor.
   7. 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 (
https://www.navcen.uscg.gov/?pageName=contactUs
<https://facebook.us19.list-manage.com/track/click?u=525f1e4a25cf3f056ef7d0926&id=0a1dc9370f&e=9866bdbb6a>).
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.


On Sun, Aug 26, 2018 at 8:35 PM Joseph Balderson <joebinc at gmail.com> wrote:

> the alberg croud is emailing a lot about the led masthead lights
> interfering with there vhf radios. I haven't experienced anything of the
> kind.
> Have heard of such a thing?
>


-- 
Eric Crawford
Crawford Marine
7520 Waverly Island Rd
Easton, MD 21601
eericcrawford at gmail.com
(410) 310-6303