Severe Interference to Segments of the Broadcast Band

April 14, 2010: As a ham radio operator, I have an interest in RF egress from systems that have the potential to interfere with radio reception. This video demonstrates the noise that shows up loudly on the AM broadcast band in one area of my town. Is this a single point failure of some hardware that has been installed? Is the noise caused by an incorrect installation of some subscribers equipment? Has there been a grounding failure somewhere? Could this be corrected with filtering? Who is at fault and who do you call to get it fixed? It is very hard for the typical consumer to determine the answers to these questions. One thing is certain, in this particular case, this is not a problem that can be resolved by a station listener.

The station you hear in the video is 1080 WTIC in Hartford, CT. This is a 50,000 watt local broadcaster that is roughly 15 miles away from this location. Notice how clearly it comes in for the first 30 seconds of the video as we cruise my neighborhood, which is not suffering from the interference problem. WTIC, which broadcasts on 1.080 MHz, is the loudest AM broadcaster in my area. It offers a wide range of popular content and is the area broadcaster for the Boston Red Sox and the UConn Huskies, making it a favored station by many.

In the video, as we approach the bridge at the 0:30 mark, we are crossing into an area of town experiencing severe interference. You can begin to hear the raspy buzz competing with the very strapping signal of WTIC just before passing under the bridge. After turning the corner, the noise begins to really roar. Oddly, notice at the 1:15 mark what happens when the radio is switched to .560 MHz (WHYN), a much weaker station located in Springfield, MA. There is no noise competing with WHYN so the noise disappears allowing this much weaker station to be heard clearly. This frequency selective behavior can make determination of the noise source rather difficult. Switching back to WTIC results in another blast of noise. After making the turn and continuing to venture into the noisy territory, notice at the 2:10 mark, that switching from WTIC back to WHYN again results in interference-free listening. The noise rises and falls all along this road and appears to be pretty much unaffected by wet weather or temperature changes.

The problem with severe interference like this is that it will not go away by itself. It requires the cooperation of all the utilities (cable, phone, power) that share space on the poles that are used to provide services to the residences along the road. Which utility is responsible in this particular case? Again, there is no way for the average consumer to determine this. The F.C.C. is the governing body that carries the responsibility for enforcing standards that minimize interference. Most consumers aren't sure what to do when faced with an issue like this, and might be tempted to live with it, but I would encourage you to contact the F.C.C. to register a complaint. In this particular case, I have registered an interference complaint with the F.C.C. (Reference Number: 10-C00211501) asking for assistance. The assistance might simply be a phone call or letter issued by them to the utilities involved to determine what needs to be done.

Note that the local power company replaced every power pole along this stretch of road back in 2007. Each pole has brand new hardware and is equipped with the new composite insulators that tend to be silent at radio frequencies. The cable company and phone company also share the poles to distribute their services (phone-internet-television) to local customers.

In the first week of May 2011 this problem suddenly went away. There's no way to be sure what it was, but based upon reports from a number of others who have experienced similar oppressive oscillations, it may have been a malfunctioning satellite receiver. It may have finally failed completely, or the user may have gotten tired of the RFI pollution to his own house. At any rate, everyone who drives through here is glad it's gone!

Category:

Science & Technology

Tags:

• Radio
• Frequency
• Interference
• to
• BC
• Band
• W1AEX

[ender06026]

On May 8th 2011 the noise abruptly stopped. So perhaps this problem is closed. My guess is that it was a piece of faulty consumer equipment that finally failed. Several people have commented to me that this issue can be caused by certain uncertified satellite television receivers that are imported from Korea. This thought has some merit as the two houses with the noisiest drop lines along the route have satellite dishes on their roofs. Whatever it was, everyone here is glad it's gone!

[Binky40SW]

Does it peak in front of any one house? Monitoring Times or Popular Communications had an artricle about how people running grow-lights in their house could be "beaconing" their pot-farms and other growing operations.

I forget the exact frequency was in the neighborhood of 2.65 MHz with powerful spurs at all the harmonics.

Just a thought...

[ender06026]

@Binky40SW Your idea has merit. I see a consistent peak in the noise while driving under two different drop lines to two residences along that path. I agree with the power company's conclusion that this noise is not the result of an issue with their hardware. It looks more and more like some consumer product that is installed within one or more residences is spewing raspy oscillations that are coupling to either the power grid, the cable feed, or more likely, the phone lines.

[ender06026]

@Binky40SW Several people have indicated that certain brands of cheap, imported satellite receivers have been found to spew oscillations from the BCB through the lower HF bands. The two noisy drop lines do in fact connect to homes that have satellite dishes on the roof. Thanks for pointing out the potential for interference from the grow-lights. It amazes me that these products seem to slip through the Part 15 certification process and end up in people's homes!

[uploadJ]

The 'trained ear' here on my end says that is some sort of switching power supply, and not insulator/surge suppressor/hardware arcing ... just an FYI from somebody who has tracked a number of these 'sources' (power line AND consumer devices) making noise on the AM and SW bands ...

Chances are, the power company didn't 'look' at 1080 kHz but chose some other clear frequency and indeed their gear is clean, but the source remains on/close to 1080 kHz ... my thoughts for what it is worth.

.

[ender06026]

@uploadJ I agree with your thoughts on this. It's definitely not broadband gap noise. It is very frequency selective and has the characteristics of a modulated oscillator, slightly above the 1.080 broadcast frequency. I happened to be driving down the road when the power company investigator was looking into this. He was totally perplexed as he could hear it on the truck's AM broadcast band radio when tuned to 1.080, but not with his test equipment, which does not cover the AM BCB.

[mec1616]

The grow lights were turned off during the BUST!

[Binky40SW]

Also, as a sidebar, two short stories:

My place of employment uses a 450 MHz LTR trunked system. They were befuddled by a source of RF interference that would sweep their channels. It was apparently a pretty powerful spur. It turned out to be broadcast band TV antenna preamps in the RV park oscilating at our work radios frequency.

I also found out one particular brand of digital to analog TV converter box effectively jams my Garmin GPS when they're both installed in my Explorer.

[Binky40SW]

@ender06026 One thing the article about grow lights mentioned-the lights are actually HID Sodium vapor lights. Apparently there is a oscilator that functions as a large incidental radiator.

The bilbs in question are meant to be installed at the top of large street lights like you find along freeways and highways-with proper shielding.

[ender06026]

December 16, 2010 UPDATE: After investigations by the power company, the ARRL, and the affected station's engineer, the source of the problem is still a mystery. On a humorous note, the FCC informed me (twice) that I should work to improve my receiver's antenna. So much for their web-based consumer RFI assistance. I'm glad this noise is not in my neighborhood, and like most other people walking and driving through this affected area, I have tuned elsewhere for entertainment.