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Airport Express picking up AM radio

C

cbiffle

macrumors member
Original poster
Jun 19, 2005
40
0
Tempe, AZ
Well, here's something you don't hear every day.

My Airport Express, which I've had since shortly after they were released, is now picking up AM radio.

The output is very quiet, but very clear; with amplified speakers it's distinct. For some reason, if I connect just the left audio channel, it becomes quite loud.

Were it wideband noise or some such, I'd chalk it up to EMI -- but this thing is quite accurately tuning in a local station (1580khz).

Has anyone else seen this?
 
Do you live near a large radio tower by any chance?

I say this because a friend of mine in Portland, OR lives relatively close to one of the main radio towers in the west hills and when they amp up the signal (in bad weather, etc.) he can sometimes get radio stations from his kitchen appliances.
 
JDOG_ said:
...he can sometimes get radio stations from his kitchen appliances.
Click to expand...


Umm... Please explain. :p


My stove has only talked to me once, and I may or may not have had way too many coffees that day. Otherwise my appliances are pretty quiet.
 
I'm confused, where can you hear the signal from? Is it coming out of the audio port on the Airport Express, or out of your computer?
But anyways, isn't the Airport Express supposed to run at 2.4 GHz, and am radio is in the KHz, isn't it?
 
EricNau said:
I'm confused, where can you hear the signal from? Is it coming out of the audio port on the Airport Express, or out of your computer?
But anyways, isn't the Airport Express supposed to run at 2.4 GHz, and am radio is in the KHz, isn't it?
Click to expand...


At a guess, I'd say the sound comes from Express-connected speakers. The AirPort runs around 2.4GHz, more or less. Still, cbiffle is saying that the station broadcasts on about 1.6GHz, which you'd think was too low. Very strange indeed.
 
mad jew said:
At a guess, I'd say the sound comes from Express-connected speakers. The AirPort runs around 2.4GHz, more or less. Still, cbiffle is saying that the station broadcasts on about 1.6GHz, which you'd think was too low. Very strange indeed.
Click to expand...
Even stranger are the talking kitchen appliances - something tells me that may have more to do with "ingested substances" rather than radio. :p
 
Batch reply:

I don't live near any transmitters (I'm a Ham and keep track of these things). The AM station it's tuning is even pretty weak in my area -- I tried it in my car with poor luck. Incidentally, the station is Radio Disney. The end result is that I can hear, very very quietly, Disney songs beneath all my music. I thought I was going crazy until I did some troubleshooting. :)

It's 1580khz, or 0.0016ghz. I suppose the 802.11b channel I'm using might be a harmonic of the carrier, but I haven't done the math.

Yes, the audio is coming out of the attached speakers. The AE itself should be electrically isolated from the mains -- it's behind a UPS, among other things.

Honestly, I don't see where there'd be enough wire to pick up the station through simple inductance. I'm wondering if this damn thing might contain an (inactive) tuner.
 
cbiffle said:
Batch reply:

I don't live near any transmitters (I'm a Ham and keep track of these things). The AM station it's tuning is even pretty weak in my area -- I tried it in my car with poor luck. Incidentally, the station is Radio Disney. The end result is that I can hear, very very quietly, Disney songs beneath all my music. I thought I was going crazy until I did some troubleshooting. :)

It's 1580khz, or 0.0016ghz. I suppose the 802.11b channel I'm using might be a harmonic of the carrier, but I haven't done the math.

Yes, the audio is coming out of the attached speakers. The AE itself should be electrically isolated from the mains -- it's behind a UPS, among other things.

Honestly, I don't see where there'd be enough wire to pick up the station through simple inductance. I'm wondering if this damn thing might contain an (inactive) tuner.
Click to expand...
That is soooo weird. Do you have AppleCare for your computer, call up them and explain it, I'm guessing they'll direct you to a 'product specialist,' they ought to know.
 
My guess it's got nothing to do with the Airport express -- you've got amplified speakers, obviously, which are exerting considerable gain on the input, and it could be that the cables to the speakers are damaged, poorly shielded, or have a dirty connection. All it takes is a bit of capacitance, and sufficient gain, and you can pick up RF with a wire; ask any electric guitar player.

Try cleaning the contacts of the cables, and/or replacing the cables. If it's severe, you may have to put a filter between the cable and the speakers.
 
cbiffle said:
Well, here's something you don't hear every day.

My Airport Express, which I've had since shortly after they were released, is now picking up AM radio.

The output is very quiet, but very clear; with amplified speakers it's distinct. For some reason, if I connect just the left audio channel, it becomes quite loud.

Were it wideband noise or some such, I'd chalk it up to EMI -- but this thing is quite accurately tuning in a local station (1580khz).

Has anyone else seen this?
Click to expand...

Do you have DSL by chance?
 
cbiffle said:
Well, here's something you don't hear every day.

My Airport Express, which I've had since shortly after they were released, is now picking up AM radio.

The output is very quiet, but very clear; with amplified speakers it's distinct. For some reason, if I connect just the left audio channel, it becomes quite loud.

Were it wideband noise or some such, I'd chalk it up to EMI -- but this thing is quite accurately tuning in a local station (1580khz).

Has anyone else seen this?
Click to expand...

You may want to give your psychiatrist a call.
 
Yeah I used to have this problem a while back with an old pc connected to DSL.... there was muffled German radio coming through the pc speakers. very odd!
 
I've had this happen to me a few times.

1) My powersub was playing a radio station very quietly, but it was perfectly clear, since then, the AM ghost has yet to reapear.

2) When I was little, we had some cheap walkie-talkies, and walked near the green TV box in front of my house and BAM...ABC news, i just stood there and listened, and eventually got blasted by a nerf sniper.......good times...good times.....
 
louis_sx said:
Oh, and when my brother-in-law is over, my computer speakers play static about 2 seconds before his celular phone rings.
Click to expand...

My speaker do that as well. Its nice, I know a few seconds before i get any call or text. Also, I pick up radio on some very poorly shielded speakers I have connected to my stereo, which is connected to my pbook. If they're on for a while, i start getting AM as well.
 
Ah! The wonders of electrodynamics! :)

This happened with my cheap 5.1 speakers once. It was loud enough to keep me awake at night. Unplugged them for a minute, and the problem went away.

It suuuure is creepy though.
 
The noise isn't coming in through the 2.4 Ghz 802.11 carrier. You are suffering from a common phenomenon of audio equipment called audio rectification. Some portion of the circuitry that drives the speakers attached the to Express (including the speakers themselves) is acting as an unwanted radio antenna.

Electronic devices are supposed to be shielded/grounded/filtered from this kind of interference, and if you are picking up radio waves it means they are 'leaking' in somewhere. Plug in a different set of amp/speakers and see if that makes a difference. Attach the express to a different wall outlet. Use a different 8mm patch cable. If you can find the source of the 'leak' you can try to correct it with shielding/grounding/filtering yourself, or just use different equipment. If the source turns out to be internal to the Airport Express, take it back to wherever you purchased it from, because that qualifies as a defect.
 
How is the Airport Express hooked into your system? What kind of internet service do you have (Cable or DSL)? When you installed DSL did you leave it up for a number of days so that it could calibrate to the conditions of your phone line?

The DSL band happens to coincide with the AM radio band so if your DSL connection did not properly calibrate to chose the frequencies with the least interference and you have your modem plugged into the Airport Express you might have your culprit there. I am almost positive that if you are not wired directly to the Airport Express from the modem then I am barking up the wrong tree.
 
CanadaRAM said:
My guess it's got nothing to do with the Airport express -- you've got amplified speakers, obviously, which are exerting considerable gain on the input, and it could be that the cables to the speakers are damaged, poorly shielded, or have a dirty connection. All it takes is a bit of capacitance, and sufficient gain, and you can pick up RF with a wire; ask any electric guitar player.

Try cleaning the contacts of the cables, and/or replacing the cables. If it's severe, you may have to put a filter between the cable and the speakers.
Click to expand...


yep, RAM is right... everyone stop guessing....
 
I have had the exact same problem with my Airport Express. I don't know if it's AM or FM but there is definitely radio coming through and it is very annoying. I hear it when I'm watching TV, listening to music, etc. I have my AE hooked up to my stereo. I believe ElectricSheep is correct, and thank you for posting that potential solution. I will definitely give it a try.

I also grew up near some radio towers, and we used to hear the radio in EVERYTHING - our portable tape players, our phones, even in our pipes once. Anything electric would pick up the radio signal.

So all you people joking about seeing a psychiatrist and whatnot, well, haha, but you're not really helping us solve this fairly annoying little problem.

I'll let you know how my search for the leak goes. Cheers!
 
CanadaRAM said:
My guess it's got nothing to do with the Airport express -- you've got amplified speakers, obviously, which are exerting considerable gain on the input, and it could be that the cables to the speakers are damaged, poorly shielded, or have a dirty connection. All it takes is a bit of capacitance, and sufficient gain, and you can pick up RF with a wire; ask any electric guitar player.

Try cleaning the contacts of the cables, and/or replacing the cables. If it's severe, you may have to put a filter between the cable and the speakers.
Click to expand...

Yup, as a musician I'll agree to this. Had a bad speaker cable for quite awhile that picked up a local Latin music station.
 
Well because its an analog signal, sometimes the wires can just be the right length to receive ,I used to have some old speakers that when I put the cable partway it would pick up clear am or fm radio. Similar to this, why is it my speakers make that beeping noise when there are cell phones nearby?
 
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