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Thread: FM Interference

  1. #1
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    FM Interference

    What are the worst culprits for generating FM interference in the world of CarPCs?

    When the carPC is on, I get dreadful FM reception on the headunit.

    If I disconnect the VGA cable at the PC, the reception is back to normal - even if the screen is still on. I therefore deduce it's EMI from the VGA signal that causing the problem, and not from the PC intself or from the screen backlight.

    I have a Xenarc 700TSV, moulded into the dash just in front of the gear lever, and the head unit is about 12 inches above it.

    I've tried to re-route the radio antenna lead away from the screen and place some copper shielding between the two, but it doesn't make much difference.

    Is it possible for the VGA cable to be affecting the FM reception further back in the car? Both PC and antenna are at the back, and have cable running through the car - at one point they are very close together.

    The VGA cable is a middle quality one - not the best, but not the cheapest. This weekend I will try to swap it with a better quality triple shielded one, and re-route the antenna and VGA cables to avoid each other.

    Anything else I could try?

    Thanks

    Ian

  2. #2
    VMS
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    i got the same problem, anyone?
    Vehicle Media Systems
    Australia Car PCs www.vmscarpc.com.au

  3. #3
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    drop the HU :-)

  4. #4
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    Tried to re-route the antenna cable today, and it made no difference - I also re-tried the disconnecting VGA cable - which also didn't help.

    I don't know why it helped last time and not now, but I no longer think it's the screen to blame.

    I've also disconnected the GPS mouse, bluetooth dongle and USB cables with no effect.

    So my latest theory is that it's coming from the PC itself - but which component - power supply? hard disc? motherboard?

    Any suggestions?

    Ian

  5. #5
    Variable Bitrate 307SW_NLD's Avatar
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    I have found the power supply of the LCD screen to be a source of interference. There is a little switching PSU in the "egg" of my Lilliput and I need it to place it as far apart as possible from any audio cables. Probably be better of using the PSU of my Carpc for the LCD.
    My car: 2009 MAZDA CX-9 3.7L V6 runnin on LPG (Liquid Petrol Gas)
    Hardware: None at the moment
    Software: None at the moment
    See: Velleman K8055 Plugin for Road Runner

    Progress: [XXXXXXXXXX] 0 % DONE

  6. #6
    Newbie Monkee's Avatar
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    I have the same problem and the only things that are hooked up right now are the PC components in the trunk. What gives?

  7. #7
    Newbie pleyraki's Avatar
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    Quote Originally Posted by Monkee View Post
    I have the same problem and the only things that are hooked up right now are the PC components in the trunk. What gives?
    I solved the problem by just removing an FM signal booster I had installed in the past! (I had almost forgotten I had put it in there long before my carpc!). Also check if you have an antenna with a booster in it. You may then have to replace the antenna with a plain one, or disconnect the power from it.

    Hope this helps.
    A. Plevrakis
    Iraklion, Crete, Greece.

  8. #8
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    Quote Originally Posted by pleyraki View Post
    I solved the problem by just removing an FM signal booster I had installed in the past! (I had almost forgotten I had put it in there long before my carpc!). Also check if you have an antenna with a booster in it. You may then have to replace the antenna with a plain one, or disconnect the power from it.

    Hope this helps.
    I'll try that - my car DOES have a booster antenna, so I'll disconnnect the power and see what happens!

    Thanks

    Ian

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