[RFI] LED Traffic Light RFI

EDWARDS, EDDIE J eedwards@oppd.com
Fri, 27 Sep 2002 14:37:44 -0500

YES!  I posted a similar question here last Dec.  We started having problems with these LED lights in Omaha, NE last year, and the traffic engineer laughed at first when I called to let them know about it since I only knew about QRM to/from VHF ham bands (and possibly our company's pagers on VHF as well).  We also had reports from hams that they could control the left turn signal using 2 meters!  No need to wait to turn, just key up and GO!

Then when the city's contractor for radio systems (local mobilecom shop) called to tell them about it, they got real serious since they were getting it on the fire & sheriff VHF freqs as well.  

They found that certain mfr's switching power supplies are noise junk generating broadband noise.  I don't remember the mfr's name, but only one of them was bad I think so they switched out to the other brand.  If you need specific names, I can call our traffic engr here and ask.

de ed -K0iL
-.-. --.-  -.-. --.-  -.. .  -.- ----- .. .-..  .-.-.  -.-
Ed Edwards, Communications Engineer
2-Way & Paging Systems
Omaha Public Power District
Phone: (402) 552-5425
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> -----Original Message-----
> From:	William G. McDowell [SMTP:k4cia@mindspring.com]
> Sent:	Friday, 27 September, 2002 2:01 PM
> To:	rfi@contesting.com
> Subject:	[RFI] LED Traffic Light RFI
> Has anyone experienced RFI from these new LED traffic lights?   I live about
> 800' from an intersection that has several of them.  A broad band RF
> emission is radiated when the red and green lights are illuminated.  The
> noise stops when yellow (caution) is lit as the lights change.  Sounds just
> like line noise on the receiver but its coming from the lights.  I've
> confirmed this by using a portable SW near the intersection.
> Any advice appreciated.  Have called a state traffic light engineer but did
> not get a return call yet.
> Yet another obstacle to overcome in this quest for semi-quiet bands.
> 73
> Bill, K4CIA
> Raleigh NC
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