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JVC boogie

Discussion in 'Roadster' started by slcasner, Sep 1, 2012.

  1. slcasner

    slcasner Member

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    The faceplate on the JVC head unit that was standard on 2008 Signature 100 Roadsters will automatically rotate outward at the bottom to one of four settable angles. When driving home from work a couple of nights ago, I went to adjust the volume and noticed that the faceplate was bobbing in and out. Strangely, it was in time with the beat of the music I happened to be listening to at the time. I had a hard time trying to power off the unit to make it stop, and then a hard time trying to power it on again later. It behaved normally after I did get it to power on again.

    Has anyone else seen this?
     
  2. dhrivnak

    dhrivnak Active Member

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    Fortunately not. Ocassionally it will reboot, but i have to catch it dancing.
     
  3. Doug_G

    Doug_G Lead Moderator

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    It sounds like the same (or very similar) JVC unit is in my 2010 2.0. It's never boogied, but once in a while it will start making funny noises and ripples appear across the screen. It will keep doing that, even if its power switch is cycled, until the car is turned off. Then it goes back to normal.

    Also every time my cell phone transmits a data burst I can hear it through the car speakers. It doesn't matter if the radio is on or not; as long as the unit is powered up I hear the sound.
     
  4. doug

    doug Administrator / Head Moderator

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    GSM phone I assume.
     
  5. Doug_G

    Doug_G Lead Moderator

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    Yes, it is. Took me a while to figure out it was the phone... started to get suspicious when my computer speakers popped out the same sound one day.

    The ripply screen and similar sound seems to be the JVC on its own - or maybe the Roadster; haven't figured that out yet. Has only happened a couple of times.
     
  6. NigelM

    NigelM Recovering Member

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    Ever wonder what it's doing to your head? :eek:
     
  7. doug

    doug Administrator / Head Moderator

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    At least you know you're getting a call before your phone rings. Somehow the GSM phones cause EMI at audible frequencies that many amplifiers pick up. I notice it all the time at public events where there is amplified sound. I'm surprised the FCC allows it.
     
  8. Doug_G

    Doug_G Lead Moderator

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    There's no law against transmitting signals below 8 kHz, at any amplitude. That said, I'd be surprised if a phone could produce substantial output at that frequency. Surely it must be a modulated signal of some kind.
     
  9. arg

    arg Member

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    GSM is time-division multiplexed with 8 slots per radio channel (ie. each radio channel carrying active phone calls is typically shared by 8 phones, each transmitting only 1/8 of the time).

    The slots are 0.577ms long, giving a repeat rate of 217Hz. So you've effectively got the RF carrier 100% AM modulated at 217Hz - readily detected up at any preamp input or microphone unless you've done something to prevent it.

    I don't know about FCC, but in Europe at least it's considered to be the audio equipment's fault for picking it up. EN55020 (testing standard for TV sets, radios etc.) has an explicit test to check that such equipment is immune to GSM transmissions. However, computer speakers are probably tested against EN55024 [IT equipment] that doesn't have this test - or if they are cheap ones, the manufacturers just slap the CE mark on the side without doing any testing at all and hope noone notices!
     
  10. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    I hear that a lot of folks will pay extra to have the phone come through their car's audio speakers--and you got it for free.
     
  11. Doug_G

    Doug_G Lead Moderator

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    :tongue: My ears aren't so good at decoding binary.
     
  12. brianman

    brianman Burrito Founder

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    How 10010101-ist of you.
     
  13. Doug_G

    Doug_G Lead Moderator

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    There are 10 types of people in the world: those who understand binary and those who don't.
     
  14. rabar10

    rabar10 FFE until Model 3

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    I so wish you had caught this on video...

    BTW, good thing the mods never derail threads ;-)
     
  15. Doug_G

    Doug_G Lead Moderator

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    Not my section. :tongue:
     
  16. slcasner

    slcasner Member

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    #16 slcasner, Mar 11, 2013
    Last edited by a moderator: Mar 13, 2016
    Today it happened again, and I did catch it on video this time. After that, I tried to make it stop by pushing all the buttons on the unit to no avail. Even turning off the car did not make it stop. Finally I was able to push the faceplate release button and take the faceplate off. That made the unit settle down, so when I put the faceplate back on it was quiet. I then started the car again, turned on the JVC, and proceeded on my way to work.

     
  17. Doug_G

    Doug_G Lead Moderator

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    That is simply hilarious! "JVC Boogie" fits it to a tee!
     

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