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Thread: USB FM/AM tuner with RDS/RBDS

  1. #71
    Maximum Bitrate Seth's Avatar
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    Me too

  2. #72
    Raw Wave rando's Avatar
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    Quote Originally Posted by The Grinch
    The reason I have asked for USB audio is because I don't have any audio channels free... unless someone can tell me a way to have four channel audio out and a line-in on my EPIA MII-10000.
    Easy, add a USB sound device. I use the Audigy AND iMic AND still have the EPIA sound ports available if needed. I only listed USB digital audio as a nice to have feature, since that's what the OP requested in the first place. If the sky is the limit, might as well include it. Reality, cost and time always have their way of limiting the must have from the nice to have features.

    As for the reception quality, I have no idea if that is a property of the tuner chip or one of the MANY external support circuits it requires. Even before Seth's post, I had been looking at this exact issue. I studied a couple of the ICs used in old head units I had lying around (downloaded their datasheets) and the one in my Radioman. Alas, my RF electronics experience is pretty close to nil and I know even less about FM/AM radio tuners. I wasn't able to make heads or tails out of the problem.

  3. #73
    Raw Wave rando's Avatar
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    Quote Originally Posted by Seth
    Me too
    Me three.

  4. #74
    Maximum Bitrate Seth's Avatar
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    Quote Originally Posted by rando
    As for the reception quality, I have no idea if that is a property of the tuner chip or one of the MANY external support circuits it requires. Even before Seth's post, I had been looking at this exact issue. I studied a couple of the ICs used in old head units I had lying around (downloaded their datasheets) and the one in my Radioman. Alas, my RF electronics experience is pretty close to nil and I know even less about FM/AM radio tuners. I wasn't able to make heads or tails out of the problem.
    rando you're right in the spot. Reception quality is the result of an equation in which the tuner chip is one of the variables. 50% of the result lies to the quality of the band-pass filter/demodulation support circuitry. As you may have noticed HU's have an oversized tuner module. I wish we could have our hands on such modules but we can't. We have schematics of them but we can't build them since lot of the components are manufacturer specific and are not available publically.
    Something that balances the situation is the fact that microelectronics technology advances every day and more efficient/small/cheap components are available to the public.
    With the current design we hope to reach 70-80% of a commercial HU's sound/reception quality.
    I'll try to post a "beta" stage design by the end of next week so that we can discuss/share knowledge in order to make this as good as it gets.

    Thanks


  5. #75
    Raw Wave rando's Avatar
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    70-80% ... hmmmm. I'm struggling to imagine how that maps into 'perceived' reception quality. In any case, I'll eagerly await whatever you come up with. Thanks in advance for whatever you produce.

  6. #76
    Jesus Freak antimatter's Avatar
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    Quote Originally Posted by Seth
    rando you're right in the spot. Reception quality is the result of an equation in which the tuner chip is one of the variables. 50% of the result lies to the quality of the band-pass filter/demodulation support circuitry. As you may have noticed HU's have an oversized tuner module. I wish we could have our hands on such modules but we can't. We have schematics of them but we can't build them since lot of the components are manufacturer specific and are not available publically.
    Something that balances the situation is the fact that microelectronics technology advances every day and more efficient/small/cheap components are available to the public.
    With the current design we hope to reach 70-80% of a commercial HU's sound/reception quality.
    I'll try to post a "beta" stage design by the end of next week so that we can discuss/share knowledge in order to make this as good as it gets.

    Thanks

    Well i hope that it is better than the Radio Xtreme. I'd say if you are starting from the ground up that you should do everything in your power to make this a solution that first and formost addresses the Crappy USB radios that we are stuck with.

    80% isn't that bad but anything lower is pushing it. People will still want it becasue it has AM and RDS but without propper reception people will be left feeling unsatisified like i am feel with my radioxtreme.

    Once again thanks for taking this project on and hope that you work on getting your hands on an oversized tuner module

    Cheers
    -Jesus- King of Kings Lord of Lords

  7. #77
    Maximum Bitrate Seth's Avatar
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    Well it's all theory for now but you can come with an estimated performance figure if you calculate the SNR ratios / AGC performance / frequency slip tolerance / frequency tune step etc. and compare them to the values of an actual HU. I have schematics of various HU's and such performance numbers are there for the technician's reference.


    EDIT: antimatter thanks for your support and all you guys

  8. #78
    See me in my wet t-shirt. stevieg's Avatar
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    I'll take a couple too

    If someone could make it so it also on the same board has a amplifier that can be turned up/down/front rear balance through the USB it would be great as well - I.E. radio goes to line in and amplifier onboard is only to amplify the output of the PC upto maybe 40W RDS - rather than the usual of having an extra amplifier seperately?
    Ford Focus MP3 : www.stevieg.org/carpc Blog Updated 29 January 2009!
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  9. #79
    Maximum Bitrate Seth's Avatar
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    Quote Originally Posted by stevieg
    I'll take a couple too

    If someone could make it so it also on the same board has a amplifier that can be turned up/down/front rear balance through the USB it would be great as well - I.E. radio goes to line in and amplifier onboard is only to amplify the output of the PC upto maybe 40W RDS - rather than the usual of having an extra amplifier seperately?
    That is extreme!!!

    I don't think this is something that could be done (easily). It could lead in a lot of design time and unnecessary complexity / undesired cost.
    Something interesting though is this:

    TEA6320; Sound fader control circuit

    * Source selector for four stereo and one mono inputs
    * Interface for noise reduction circuits
    * Interface for external equalizer
    * Volume, balance and fader control
    * Special loudness characteristic automatically controlled in combination with volume setting
    * Bass and treble control
    * Mute control at audio signal zero crossing
    * Fast mute control via IC-bus
    * Fast mute control via pin
    * IC-bus control for all functions
    * Power supply with internal power-on reset.

    it may be incorporated by us or someone else in the future.
    Attached Images Attached Images

  10. #80
    Low Bitrate ste1806's Avatar
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    Talking

    i'd buy one to

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