Airport Express picking up AM radio

Discussion in 'Mac Accessories' started by cbiffle, Oct 25, 2005.

  1. cbiffle macrumors member

    Joined:
    Jun 19, 2005
    Location:
    Tempe, AZ
    #1
    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?
     
  2. mad jew Moderator emeritus

    mad jew

    Joined:
    Apr 3, 2004
    Location:
    Adelaide, Australia
    #2
    Very bizarre. Change the channel if you're getting sick of it. You'll probably get better range too. :)
     
  3. JDOG_ macrumors 6502a

    JDOG_

    Joined:
    Nov 19, 2003
    Location:
    Oakland
    #3
    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.
     
  4. mad jew Moderator emeritus

    mad jew

    Joined:
    Apr 3, 2004
    Location:
    Adelaide, Australia
    #4

    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.
     
  5. EricNau Moderator emeritus

    EricNau

    Joined:
    Apr 27, 2005
    Location:
    San Francisco, CA
    #5
    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?
     
  6. mad jew Moderator emeritus

    mad jew

    Joined:
    Apr 3, 2004
    Location:
    Adelaide, Australia
    #6

    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.
     
  7. EricNau Moderator emeritus

    EricNau

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    Apr 27, 2005
    Location:
    San Francisco, CA
    #7
    Even stranger are the talking kitchen appliances - something tells me that may have more to do with "ingested substances" rather than radio. :p
     
  8. cbiffle thread starter macrumors member

    Joined:
    Jun 19, 2005
    Location:
    Tempe, AZ
    #8
    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.
     
  9. EricNau Moderator emeritus

    EricNau

    Joined:
    Apr 27, 2005
    Location:
    San Francisco, CA
    #9
    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.
     
  10. CanadaRAM macrumors G5

    CanadaRAM

    Joined:
    Oct 11, 2004
    Location:
    On the Left Coast - Victoria BC Canada
    #10
    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.
     
  11. louis_sx macrumors regular

    Joined:
    Jul 6, 2005
    Location:
    International House of Louis
    #11
    I have a TV that, when it's turned off with external speakers attached, does the exact same thing, but it's a lower frequency. That's really freakin' weird.
     
  12. japasneezemonk macrumors 6502

    japasneezemonk

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    Nomad
  13. atszyman macrumors 68020

    atszyman

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    Sep 16, 2003
    Location:
    The Dallas 'burbs
    #13
    Do you have DSL by chance?
     
  14. jeremy.king macrumors 603

    jeremy.king

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    Jul 23, 2002
    Location:
    Fuquay Varina, NC
    #14
    You may want to give your psychiatrist a call.
     
  15. dcv macrumors G3

    Joined:
    May 24, 2005
    #15
    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!
     
  16. louis_sx macrumors regular

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    Jul 6, 2005
    Location:
    International House of Louis
    #16
    Oh, and when my brother-in-law is over, my computer speakers play static about 2 seconds before his celular phone rings.
     
  17. jeffzoom macrumors member

    Joined:
    Oct 8, 2004
    #17
    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.....
     
  18. runplaysleeprun macrumors 6502a

    runplaysleeprun

    Joined:
    Jul 27, 2004
    Location:
    Chicago, IL
    #18
    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.
     
  19. diddy macrumors 6502

    Joined:
    May 13, 2003
    Location:
    Las Vegas, NV
    #19
    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.
     
  20. ElectricSheep macrumors 6502

    ElectricSheep

    Joined:
    Feb 18, 2004
    Location:
    Wilmington, DE
    #20
    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.
     
  21. atszyman macrumors 68020

    atszyman

    Joined:
    Sep 16, 2003
    Location:
    The Dallas 'burbs
    #21
    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.
     
  22. superbovine macrumors 68030

    superbovine

    Joined:
    Nov 7, 2003
    #22

    yep, RAM is right... everyone stop guessing....
     
  23. dadabase1 macrumors newbie

    Joined:
    Apr 6, 2010
    #23
    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!
     
  24. slapguts macrumors 6502a

    slapguts

    Joined:
    Jan 10, 2008
    #24
    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.
     
  25. skunkworker macrumors regular

    Joined:
    Sep 9, 2007
    #25
    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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