The CGC Communicator Newsletter Web Posting

RFI FROM "LED" TRAFFIC SIGNALS

In CGC #751, Don Johnson, an RF technician at Bext, identified certain traffic signals with LED lamps as being potent sources of RFI. Although his comments concerned ham radio frequencies that were between the AM and FM broadcast bands, an observer in Poway found LED RFI in the FM broadcast band, meaning that some TV frequencies (esp. Channels 2-6) could be impacted as well.

Keep in mind that this research is in an early stage, and we should not assume that we are dealing with a large problem yet. The following e-mail from the FCC's Office of Engineering Technology reiterates Don's concerns, then recommends a specific course of action. Your help is needed.

If you file LED RFI observation with Mr. Zears as recommended by FCC/Washington, please also copy Don Johnson by sending mailto:WD6FWE@aol.com.


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From: Generic Office of Engineering Technology [mailto:oetech@fccsun27w.fcc.gov]
Sent: Friday, August 25, 2006 12:18 PM
To: donald@bext.com
Subject: Response to Inquiry to FCC (Tracking Number 847449)

Inquiry:
I have noticed recently that there is a large amount of noise being emitted by the stoplights that have LEDs (light emitting diodes) in them. As they are making enough noise to completely cover a signal that I was listening to, I was wondering if they may be possibly considered illegal radiators. The noise is broadband from at least the 80 meter band up past the 6 meter band. The noise can be heard as far as 100 yards from some of the lights. I realized what was causing it one day as I drove past one of the warning blinker lights and heard/saw my s-meter go from s1 to s8 each time the light came on and the station that I was listening to sad covered by the noise. As there are more and more of these lights being installed everywhere the problem needs to be addressed and solved. When the lights are only one block apart (about 150 yards most places) the noise never goes back to the noise floor. The stoplights noise could make it hard for emergency communicators to rear each other under marginal conditions or if they are using handheld radios. Don Johnson WD6FWE

Response:
Please contact the FCC's San Diego District Office at 858-496-5111 (or bill.zears@fcc.gov). Provide as much detail as you can, including a few specific intersections where you have observed the problem, the frequency range of the emissions, and how long you have noticed the emissions (recognizing that you may have noticed the emissions long before you realized what the source was).
Thanks for your inquiry.

Posted by Steve Blodgett
Earthsignals.com