“… screeeee… screeeee… screeeee…pshhhhttt… pshhhttt… pshhhttt… screeeee… screeeee… screeeee…”
That’s My AM radio ALL THE TIME…
What may be the cause??? Incorrect wiring??? Navigation directional Air waves…???
Our Friends the Aliens???
Come’on You Radio Geeks…
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I will move this to our General Questions forum, as that is the forum where questions with factual answers belong.
Moving thread from ATMB to GQ.
Does it happen to ‘your’ AM radio or all AM radios in your location? That’s the first thing I’d test for.
All… constantly…
AM radio works by varying the amplitude of the radio carrier wave (which is why it’s called amplitude modulation). If you’re not familiar with the term, you can kinda think of the amplitude as the volume of the radio wave. You take your varying signal and use that to vary the volume or loudness (not really the correct technical terms but hopefully it gets the point across), then the receiver basically looks for how much the volume varies and outputs that to decode the signal.
Because AM is basically encoded with how strong the radio wave is, any other radio waves on the same frequency will add to it, and once they are mixed in, there’s no easy way to get rid f them.
There are all kinds of things generating radio waves. Fluorescent lights generate radio waves. Electronic devices, especially digital devices like computers and tablets, generate radio waves. Cell phones generate radio waves, not only to communicate with (that’s how they work after all) but also just in the little processor chip’s electronic circuitry.
And if nothing else, even the universe itself generates radio waves. This is what’s called cosmic background radiation.
All of these radio noise sources mix in with your AM signal. And like I said, once they are mixed in with it, there’s no way to get rid of them. So they show up on your radio as screeches and pops and clicks and hisses and all kinds of stuff.
FM radio works by varying the frequency instead of the amplitude. By doing that, the receiver just locks onto the frequency as it changes and tracks the frequency back and forth. Any changes in amplitude due to noise or whatever are completely ignored, until the FM signal gets so weak that it’s hard to pick it out of the background radio noise in your area. This is why FM doesn’t suffer from the same types of noise problems that AM has.
Trying to get rid of AM radio noise can be challenging in some areas. Look for neon signs nearby and locate your radio as far away as possible from them. Fluorescent lights can cause issues. Dimmer switches can cause issues. A nearby cell phone will cause AM radios to chirp as the phone talks to the cell tower, and the cell phone talks to the tower even when it’s not making a call (if nothing else the tower is basically just saying “yo, u still there, dude?” and the phone is going “yup, I’m here, bro” - that way the phone company knows which cell to route incoming calls to).
Wi-fi, microwave ovens, and other electronics can also cause radio interference. The best you can really hope for is to just move the AM receiver around (if that’s an option) and try to find the best place for low-noise reception.
Tanx for the info > engineer_comp_geek
That’s sounds like a good starting point
Almost 30 years ago, I was a data-entry worker in an office that had a printer which, if it was running, would interfere with one of the NPR stations in that area. If the printer was running, I would have to switch to the second choice of stations to listen to “All Things Considered.” It would literally drown out that station, which was indeed on the AM band.
Back in the old days, Apple II computers were notorious for AM radio noise. One of my college professors liked to say that he could tell which rooms had Apples in them just by walking down the hall with an AM radio in his hand.
We also figured out that if you toggled certain I/O lines in the computer at the right frequencies, you could make “music” on any nearby AM radio. I put the word music in quotes there because it sounded pretty dreadful. But you could at least recognize simple tunes.
Did the “noise” affect all frequencies, or just certain ones, like the aforementioned printer? I should add that the printer was a few years old, which was ancient by those standards.
IO Lines ?
The CPU itself was running at 1 MHz and current rush would account for some spread of that through the AM range… the power supply was a switch mode ? and would thus switch at something like 1 MHz as it was free to charge capacitors whenever it decided to.
But I don’t understand what IO ports you were toggling… you were perhaps affecting the video output ? Maybe RAM bank switching thus changing the amplitude of noise from the RAM.
You might be able to fix this problem with a Christmas present! Two questions: what are the call letters of the AM stations that you listen to and how close are you to their antennae?
The reason I’m asking is that an HD radio might fix the problem. You may know that many FM stations broadcast with digital HD radio which makes the sound much better plus allows side channels on the same frequency. For example KEZK-FM in St. Louis has 4 channels with different content all at the same frequency.
That’s all well and good for FM; however, AM stations can also broadcast in HD. It makes the crappy AM sound like an FM station! KMOX in St. Louis broadcasts its AM in HD and it sounds much, much better. Also remember that I mentioned KEZK has 4 channels? Well one of them is KMOX. So you can listen to KMOX on regular AM, HD AM, and even HD FM.
But there’s a few catches. 1. You need an HD receiver. Many cars come with them; however, you can buy them for the home also or even as a portable radio. 2. You need to be pretty close to the antenna. Digital HD is line of sight (basically) so you probably need to be within 10-20 miles of the station to pick it up. 3. Your stations needs to broadcast in HD.
It does and still continues… and it’s not a printer or any other peripherals… We turn them off and unplug them when not in use…
Tanx… That was Our next move…