Name that Ware September 2007

The ware for this month is actually not a picture. It is a sound clip.

Click on this link to download and listen to the clip.

Many may recognize this sound, but I think few actually know what makes this sound. I’ve heard it in many contexts, but I was convinced to make this a contest candidate when I heard it in a radio recording of General Petraeus’ progress report to congress on NPR (you can hear it just barely in one of the sound clips on this page, under Audio Highlights, “Crocker warns against…”). I’m sure the recording engineer wasn’t too pleased when choice soundbites had this playing in the background.

The challenge this month is to name the type of ware and the phenomenon that generates this sound.

19 Responses to “Name that Ware September 2007”

  1. Dan says:

    This sounds very much like interference from a cellular phone switching between cells (e.g. when driving through a tunnel) or receiving a call or message.

  2. This sounds a LOT like inducted interference from a GSM mobile.

  3. This is what happens when a GSM phone gets near a pair of speakers *and* the phone receives data from the tower (incoming call, SMS, EDGE data, etc.).

  4. rob friedman says:

    The sound is a mobile phone signal, being picked up by a speaker due to close proximity of the speaker cable. More specifically it’s the initial back and forth between the tower and mobile device, before your phone starts ringing.

  5. Julian Calaby says:

    Ok, splitting the clip up into several parts:
    1. first part – sounding like a buzzy tone
    I’d say that this is data transmitting over the GSM link.
    At which point something unknown happens and we get the
    2. dit ditdit, dit ditdit part
    This is (I believe) the GSM phone syncronising with the tower in preparation for actually sending / receiving data. (I keep my phone near my headphone socket so I can hear this when it receives a call. – as it also happens when I get messages, I’m guessing it’s generic, not specific to just getting a call)
    3. continuation of buzzy tone from part 1.
    I’d guess that this is the continuation of the transmission in progress from part 1. (voice, EDGE data, whatever)

    As such, I’d guess that this is the tones you’d hear from GSM interference with another piece of audio equipment when the phone loses and re-establishes it’s connection to the tower.

    Also, something else of note is that you tend only to hear the actual synchronisation and the first couple of seconds of the data stream – I’m guessing that the phone limits it’s transmission power when it has a good signal, then bumps it back up when it starts to get transmission errors.

    Of course, I’m probably wrong, and both Dan, Jonathan and Paul got there before me =)

  6. Karl says:

    Julian seems to hit it on the head. The first part sounds like a GPRS (or EDGE?) download. I’m guessing the second part is re-registration with the tower. My phone does this when initially powered on, and at regular intervals. The final part is either a data transmission, or more likely, a voice call (since you can hear the bursts of data in the first part, but voice calls have a continuous transmission).

    Someone actually made an amusing music video about this problem, after his phone blew out his speakers:

  7. Jered says:

    All of the previous posters are correct; that’s definitely the RF interference of a TDMA (almost certainly GSM) mobile device.

    The reason for the buzz is the nature of time-division mulitple access (TDMA). In the US, we operate mobile phones at 850 Mhz and 1900 Mhz; in Europe, 900 Mhz and 1800 Mhz. Good so far; that’s not going to make noise that we can hear. TDMA fits more subscribers into the same bandwidth by assigning different terminals different timeslots (vs. CDMA, which uses black magic). These timeslots happen to be spaced 4.615 ms apart, yielding a signal envelope which looks a lot like a dirty 217 Hz square wave.

    All sorts of things (like “wires”) are good at picking up a 217 Hz square wave at 0.5 W, and 217 Hz is conveniently smack dab in the middle of our auditory capabilities.

  8. harper says:

    I get the exact same interference sound on the baby monitor when a cell phone is sending signals nearby. It happens right before a call comes in, so I would think that it is a cell phone acknowledging that it is on a given tower before the call signal is initiated.

    Since the baby monitor operates on the 2.4 gigahertz spectrum and the cell phone normally does not, I would think that the close proximity of the cell phone to the monitor is causing leakage into that spectrum. Since by law the 2.4 gig spectrum is open and must accept any interference, the sound of the interfering signal is played on the monitor (or is received by the wireless mic in the case of the Petraeus hearing).

  9. Andrew says:

    As others have posted above, this is almost certainly RF interference from a GSM cell phone made audible by the TDMA nature of the GSM air interface coupling onto an audio circuit.

    The fact that there is complete silence in the middle of the clip says that the phone stopped transmitting for a short period, this could be either because the clip captured two separate air interface procedures (i.e. the end of a voice call followed by a location update or an SMS or something) or that it was a recording of a GPRS session where the phone was not transmitting any data during the silence period.

  10. Yan says:

    I frequently generate a sound quite similar to this with a CDMA phone and a radio alarm clock. I originally thought my alarm clock was dying (one of my motiviations for getting a chumby), until I witnessed the same sound with an Bose iPod dock and a friend’s cell phone.

  11. Jack says:

    The first part is data transfer, the second after the silence is an incoming call.

  12. roby says:

    The type of ware that generates this sound is a GSM cell phone and the phenomenon is called EMI (ElectroMagnetic Interference).

  13. Kriss says:

    I agree, cellular RF during a “tower ping/update.”

    I wonder if the iPhones have the problem if someone is listening to some tunes and a call starts.

  14. Jeremiah says:

    Yep. Cell phone (analog or digital) near something metallic connected to a recording device. The phone is sending and/or receiving data of some kind.

  15. pj says:

    uhh…. I guess this clip will be a mystery only to Americans. Anyone in Europe / Asia will have heard this a million times. From the Car stereo while driving, from amplified speakers (Computer), and on the phone (landline). In all cases you will find a cellphone in close proximity.
    I hear this almost every day on conference calls where some participant receives an incoming call on their mobile.

  16. Kriss: “I wonder if the iPhones have the problem if someone is listening to some tunes and a call starts”

    Yep, I noticed that right away. The iPhone was my first GSM phone, and wow, if I leave it lying on the desk within a foot or two of some computer speakers, the RFI in the speakers is louder than the phone’s own ringer.

    I also had an iPod mount installed on my dashboard for it, before I learned that its output connector is incompatible with most iPod line-out cables. The car iPod mount is still very handy when using the phone’s Maps application, but it’s close enough to the stereo that the noise becomes obnoxious in a hurry.

    It strikes me that GSM modulation’s tendency to get into audio systems could be turned to the power of good. A pulsed 800 MHz transmitter with a handheld Yagi would be small enough to fit in a portable hard-drive housing, and could probably put out 10KW ERP or more at the right PRF. Imagine the effect on those obnoxious cars who pull up behind you blaring mariachi music or 50 Cent or some damned thing at 120 dB…

  17. DW says:

    I agree it’s EDGE traffic getting picked up by a nearby amp , but I’ll go further and say it’s a BlackBerry, and if I had to guess I’d say an 8700.

  18. Anna says:

    What if you hear that sound and are not receiving an incoming call or message on your cell phone?

  19. Not that I’m impressed a lot, but this is a lot more than I expected for when I found a link on Digg telling that the info is quite decent. Thanks.
    p.s. Year One is already on the Internet and you can watch it for free.