There are 2 intersections I pass through every day on the way to and from
work, where the Kansas City 146.82 repeater is completely blanked out by
noise, even though I've got a full strength signal from the repeater. I've
never noticed whether the effect occurs on other repeaters or not, but it's
interesting that the frequency reported below is the same.
I've never correlated the interference with the changing of the traffic
lights, instead attributing it to noisy overhead power lines nearby; it
seems to be worse during periods of wet weather. I'll try to pay closer
attention this week and see if I detect any trends.
-Marty NW0L
martyt@pobox.com
At 03:05 PM 10/7/2001 , Ed - K0iL wrote:
>Has anyone else out there noticed this problem in other cities?
>73,
> de ed
>-.-. --.- .... .- -- ... -.. . -.- ----- .. .-.. -.-
> Ed Edwards -- K0iL
> PO Box 375 k0il@arrl.net
> Elkhorn, NE 68022-0375 k0il@qsl.net
>--... ...-- . ... --. .-.. - --- ..- --- -- ...-.- . .
>
>-----Original Message-----
>From: Bill Jackson [SMTP:k9rz@radiks.net]
>Sent: Sunday, 07 October, 2001 9:37 AM
>To: Aksarbentalk
>Subject: [K0USA-AKSARBENtalk] Traffic Signal RFI
>
>Since .94 is down, I have spent more time monitoring some of the other
>repeaters
>while motoring around Omaha. A couple of weeks ago, I started to notice a
>pattern that when I pulled up to certain intersections in west Omaha, signals
>would get rather noisey, even though they were 1/2 scale to 3/4 scale on
>S-meter. I noticed this effect particularly while listening to 146.82. The
>noise is almost pure white noise, not raspy like power line interference or
>electrical noise. I thought it might be coming from the computer in my Ford
>Ranger, but could not make it happen in my driveway, so I guessed it was
>something external to the truck.
>
>Yesterday, I may have had a major break in the case. I was sitting at the
>exit
>from Home Depot on 144th street waiting for the light to change. I
>noticed the
>white noise was almost blanking out 146.82, even though the S-meter on the rig
>was almost full scale. When the cross walk lights on 144th Street changed
>from
>a steady "Walk" to a flashing "Don't Walk", the noise level started pulsing in
>time with the flashing of the "Don't Walk" signs. The noise did not go
>completely away, but was changing in level enough to notice. Since the
>intersection to Home Depot is new, I notice it has a new style of cross walk
>lights that appear much brighter than ones using ordinary incadescent
>lamps. I
>wonder if these are some type of low energy, long life gas discharge lamps
>similar to the ones that have been written up in QST that are known to cause
>RFI?
>
>Have any of you also noticed this effect? This could be a major problem for
>public safety communications. Imagine an accident at an intersection with
>these
>lights installed and a policemen with the portable radio trying to communicate
>to the dispatcher.
>
>I plan on watching for this effect at other intersections to see if there is a
>pattern.
>
>73 de Bill
>
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