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Thread: Me experiences with the D-link USB radio

  1. #21
    Variable Bitrate craigyb's Avatar
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    Mastero, looks good, but we need clearer pictures of what you actually did.

    I was going to lose the ground connection so as to stop the loop around the car. PC - USB - Dlink - PC as I thought thats why I was getting so much noise.

    As for reception, you are basically saying you reversed the polarity of the aerila connections? have you got some more PICS of what you cut and what you soldered?

    Craig
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  2. #22
    FLAC Mastero's Avatar
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    yes

  3. #23
    FLAC LESLIEx317537's Avatar
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    OK,

    When I get time, I will reverse the antenna connections and post results.

    I hope it helps, I never got good reception on my Head Unit when the Computer was on anyways.
    SP13000|M2-ATX|512MB DDR400|2.5" 7200RPM S-ATA|Trans-7"|Slim SL DVD-CDRW|KEH 5.1 DSP|SB L!ve Ext|Gyration PowerMate|BT|WiFi|GPS|WinXP|VoomPC
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  4. #24
    FLAC Mastero's Avatar
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    Craig
    the dlink is back in the car its gonna take a lot of trouble to get it out for pictures maybe sunday.

    The onboard soldering what i have done is what improves the reception somehow now i get good reception without raising the ant.

    The Pinout of a normal Headunit ant is the opposite of the D-link.

    So when you cut the ant cable there is one core in center and sheild outer. just interchange it the center goes to the outer of the D-Link.

    The line in modification helps a lot its something to do with the USB grounding.

    cheers
    Mastero

    Quote Originally Posted by craigyb
    Mastero, looks good, but we need clearer pictures of what you actually did.

    I was going to lose the ground connection so as to stop the loop around the car. PC - USB - Dlink - PC as I thought thats why I was getting so much noise.

    As for reception, you are basically saying you reversed the polarity of the aerila connections? have you got some more PICS of what you cut and what you soldered?

    Craig

  5. #25
    FLAC Mastero's Avatar
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    Quote Originally Posted by LESLIEx317537
    OK,

    When I get time, I will reverse the antenna connections and post results.

    I hope it helps, I never got good reception on my Head Unit when the Computer was on anyways.
    While you are at it do the solder modification which will change reception like crazy.

    mastero

  6. #26
    Low Bitrate rmjjensen's Avatar
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    I'm looking to maybe buy a D-Link usb radio for my carputer so I stumbled onto this thread.

    Well, I'm an engineering student and I've learned just a little bit about antennas. Simply making the connections with the car's antenna and the D-Link's antenna plug will not get you the proper reception you desire. It's called Impedance matching.

    To get the best signal, with no reflections in your transmission line you'd need to match the output impedance of the D-Link USB radio to that of the car antenna which is standard. I'm not sure what the D-Link's impedance is, but my guess is that it is relatively high because it uses an RCA type jack (maybe 300). The impedance of the car antenna is relatively low, estimate maybe 50 or 75 ohms.

    Like I said I'm just a student so I'm no expertm, but I do know that if the characteristic impedance is not matched then there will be signal degredation in the antenna (transmission line). I'd love to tackle this problem if I had a D-Link ...but my guess is I will be buying one very shortly.

    I have no experience with this unit, but Maestro's addition of ground points on the D-Link makes the most sense because he/she is now changing the output impedance of the D-Link to a lower value which is closer match to the car antenna's impedance.

    My straight up guess right now would be to try a 300-75 Ohm coax converter. They sell them at Radio Shack (or anywhere) and are designed for changing characteristic impedance of lines. If persay, the D-Link is 300 Ohm impedance and the Car Antenna is 75 Ohm impedance it is GAURENTEED to fix the problem. This stuff is engineered for a reason so try picking it up....it's basically a transformer. Looks like this: http://www.mpja.com/pictures/4256.jpg

    Good luck with it ......I really hope it works then I'd say I learned a good amount of info at school. Oh, and you can't just stick an ohmmeter on the antenna and on the D-Link, that doesn't measure characteristic impedance, even though the units are the same, ohms. If you want some more info do a google for Characteristic Impedance and Impedance Matching.

  7. #27
    Variable Bitrate kiztope's Avatar
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    just hitching a ride on the update train......

  8. #28
    FLAC LESLIEx317537's Avatar
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    Yeah the antenna coax I bought has a impedance of 75. The Dlink has some weird cap looking thing that says 75, but who knows what that is.

    Yeah, I took the stereo line outs and bypassed the usb cable and came straght out of the unit.

    They were not sheilded at the bottom...where the 1/8th comes out.

    So I will try those mods and see what I come up with.
    SP13000|M2-ATX|512MB DDR400|2.5" 7200RPM S-ATA|Trans-7"|Slim SL DVD-CDRW|KEH 5.1 DSP|SB L!ve Ext|Gyration PowerMate|BT|WiFi|GPS|WinXP|VoomPC
    GPSing - Digital Speedo
    Relocating headunit and extending faceplate
    Button app to Alt-Tab between two programs

  9. #29
    Variable Bitrate craigyb's Avatar
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    Anyone got there yet, too busy so far to try it out myself...
    Audi S8 supercar
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    Rear 7" screen & navplus

    Toyota Hiace Van
    Shuttle PIII 866 256Mb 10GB OPUS powered
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    Custom fit 7" TFT VGA TSK

  10. #30
    Variable Bitrate craigyb's Avatar
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    OK, did the Mastero mods, absolutely no difference in reception, but inverter wine dissappeared, so the grounding trick works.

    I'm giving up on the D-link, a good job it was only 8

    Craig
    Audi S8 supercar
    Modded Xbox 400GB HD
    Rear 7" screen & navplus

    Toyota Hiace Van
    Shuttle PIII 866 256Mb 10GB OPUS powered
    MediaCar & Mappoint 2004
    Custom fit 7" TFT VGA TSK

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