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Thread: Phone echo

  1. #21
    VENDOR - Centrafuse smeesseman's Avatar
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    Echo cancellation is one of the major OEM obstacles to introducing handsfree kits into the market. The complexity of software based algorithms to handle ECNR is beyond normal imagination, and only a handful of companies have tackled this. Off the top of my head, there was Clarity, Inc., who was bought up by CSR, and Wavmakers, Inc., who was bought up by QNX Software Systems. Other vendors may have proprietary solutions, not sure on that one. HF kit manufacturers spend thousands of man hours working on ECNR, to get things right, and that's on 1 platform, 1 cpu, 1 bt chip, you get my point. To implement on a Windows system, with so many unknowns (audio hardware, bt chip, etc...) is nearly impossible. With that all said though, with EC algorithm, both the recording device and the playback device must be buffered and processed, so using 2 soundcards will be possible in this situation, with the correct parameters.
    To get to the point now - Microsoft provides a low-end software EC system, not sure whose algorithm it is, but we plan to look into implementing this in the future.

  2. #22
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    Well I know that it is very hard to have echo canceling; but a simple program which will make the system half-dublex should solve the problem. When there is sound coming from speakers (in this case when the person calling us is speaking) the program will mute the mic. And when the sound stops it will un mute so I'll be able to talk! By this way there shouldn't be echos. But I couldn't find also this kind of program. Can you help me with that? Or isn't there any program like this?

  3. #23
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    Why is the echo cancellation so hard/expensive when my $30 speakerphone from 10+ years ago works fine?

  4. #24
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    Here's a scenario I'd like to see. But, I realize that it's probably not workable because of complexity of devices, etc.:

    I have my noise cancelling bluetooth headphone (I love my Jawbone) paired to my phone while I'm out and about, away from the car. When I get in and start-up my car, the CarPC recognizes this scenario and can unpair my headphone-phone and create separate pairing with each. Both phone and headphone paired with the PC. If that was possible, I can then use the excellent properties of my bluetooth headphone with the car integration that the CarPC provides.

    I know I can use the Jawbone with my PC for Skype, for example. I don't know if I can have multiple Bluetooth pairings with my PC. If that is possible, maybe a working model for this might be to have a dedicated car Jawbone. When I get to my car, I power off the "walking" Jawbone. My car Jawbone is already powered up and pairs to the PC as soon as I start the car. The phone then pairs to the CarPC. Then, I'm off to the races...

    Possible?

  5. #25
    FLAC Nola111's Avatar
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    Quote Originally Posted by johnk View Post
    Why is the echo cancellation so hard/expensive when my $30 speakerphone from 10+ years ago works fine?
    Your speakerphone from 10+ years ago, and most other speakerphones, are built on a half-duplex concept. In simplest terms, when the party on the other end of your call on speakerphone is speaking, they don't hear and echo of themselves b/c the mic is automatically muted while they're speaking. This is the basis of half-duplex.

  6. #26
    Low Bitrate Salmizar's Avatar
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    May want to look at http://forums.fluxmedia.net/showthre...?t=3196&page=1
    I have purchased and tested the Phoenix SOHO echo canceling card. Seems to work well.

  7. #27
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    Quote Originally Posted by Salmizar View Post
    May want to look at http://forums.fluxmedia.net/showthre...?t=3196&page=1
    I have purchased and tested the Phoenix SOHO echo canceling card. Seems to work well.
    we are hoping for a USB solution, has anyone actually tried the SOLO?

  8. #28
    Maximum Bitrate LinuxRacr's Avatar
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    Quote Originally Posted by Salmizar View Post
    May want to look at http://forums.fluxmedia.net/showthre...?t=3196&page=1
    I have purchased and tested the Phoenix SOHO echo canceling card. Seems to work well.
    This is an awesome external implementation of the PCI card so that you don't require a PCI slot!!

    Anyone know how to use the USB port only to supply 5v power to the card?
    My Car: 2001 Mazda MP3
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  9. #29
    Low Bitrate Salmizar's Avatar
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    Take a USB cable, cut it in half. Red is +5V, black is ground. White and green are for data.

  10. #30
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    ... little consideration and an invite to test it by yourself....

    Have anyone tried before to mute speakers during a cell call?
    You can see that the echo exist anyway.

    Another interesting thing is to understand why the echo si present for one time only
    for example, the caller say "hello" and will ear himself say "hello" for one time only.

    this is not exactly what an Larsen effect really is.
    Normally Larsen effect produce a several decreasing signal, 'cause is a circular effect from the mic to the speakers, until it disappear.

    So i presume there is a bug in the bluetooth stack that resend the communication at the caller also

    sorry for my pizza's english

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