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RF Noise On The AM Band

W

WCWalker

Guest
While driving along the NY Thruway this weekend I noticed a clicking or popping noise on virtually every AM frequency. I noticed it started around Rochester and I could hear throughout Oswego County and Onandaga County heading towards Albany. Only the strongest AM signals were able to wipe out the noise but weaker signals were adversely impacted by the noise.

I did not hear this noise in CT, PA or OH but I also heard it on two separate days in most of central Indiana from the Indianapolis area west to Terra Haute into Illinois.

The noise is not coming off the power lines because I drove through rural areas of CNY and Indiana where I was at least a half mile from the nearest utility line and the noise was every bit as pronounced as if I was driving right next to the lines.

Is there some kind of RF test taking place?
 
I have a somewhat similar problem at times. In my case, it disappears on rainy pavement and on certain types of pavement. It started when I replaced my tires. Next time it happens, I suggest that you stop the car, turn off the ignition & see if it's still there (in my case, all I need do is stop & the noise goes away). That will tell if it's something being picked up from the air or if it's being generated by the vehicle. Unfortunately, I haven't figured out how to stop this "tire static" for lack of a better term. But on Dec 26, WIBC is moving to FM and with it, my last reason to listen to AM in motion. So I'm just living with it for a few more weeks.
 
Bob. Yes, I did do something similar to your suggestion.

I could hear the noise when the car was stopped and the engine turned off. I pulled out the C Crane radio and I could only faintly detect the noise on that radio.

Is it possible some kind of RF filter in the car radio has kicked the bucket? I find it odd that I only heard this noise in certain places while in others it was non existent.
 
William C. Walker said:
Bob. Yes, I did do something similar to your suggestion.

I could hear the noise when the car was stopped and the engine turned off. I pulled out the C Crane radio and I could only faintly detect the noise on that radio.

Is it possible some kind of RF filter in the car radio has kicked the bucket? I find it odd that I only heard this noise in certain places while in others it was non existent.
Click to expand...
Sounds like you don't have my "tire static" issue. I don't believe radios have any kind of static filter as such. And if you're also hearing it on the C Crane, the next thing I would try is walking at least 50' from the vehicle & seeing if the noise gets weaker as you get farther away from the car. It seems pretty unlikely that there is some kind of across the dial interference that exists for dozens of miles with the intensity to wipe out all but the strong stations. While I don't know the math involved, I would think it would take tens of thousands of watts spread across the entire band to acheive that level of interference if were being created on purpose. Turn the vehicle completely off & take a hike with the C Crane next time this happens & see if that shines a light on where it's coming from. Assuming the C Crane is a typical portable with an internal ferrite rod antenna, rotate the radio & see where the static is the weakest. The interference will probably be coming from the direction of one of the narrow "sides" of the radio.
 
Yep, did that too. I was about 100 feet away from the car with the engine off. I could still hear it on the C Crane though it was very very faint. Right now I am not hearing anything in the Kansas City area and I did not hear it once I drove west past western Illinois. Initially I suspected the radio was at fault but because this noise is only occurring in specific areas like Indiana and NY I am really puzzled as to what is causing it.
 
Just for grins, are you using a cell phone charger in the car? The 12vdc charger for my moto razr phone makes lots of racket in the AM band.. Just a thought..


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Dave. Nope. I don't even own a cell phone. I also gave that a passing thought that perhaps something inside the car was causing the noise. But aside from the C Crane radio nothing else that was inside the car emitted any kind of RF.
 
Some of those little cigarette-lighter adaptors can cause a lot of noise on the AM band, whether they are for a cell phone, DVD player, TV, radar detector etc.
 
I also posted this message on the Buffalo board. Someone there has just confirmed that my suspicions are correct. He too heard the same noise on the AM band over a 100 mile area. Perhaps some nefarious plot has been uncovered. ;D Now if we can just determine the origin of the noise.
 
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