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Thread: During a call, other end of the line hears themself

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    During a call, other end of the line hears themself

    I've setup centrafuse 2.1 with bluesoleil to work with my blackberry pearl. During a call the sound to the speakers sounds good and the mic sounds clear on the other end. But the other person can hear themselves because the mic obviously picks up their voice while they speak and relays it back to them, resulting in an echo. Is there a way to turn off the mic while the other person is speaking? so that I can hear them through the speakers, but they can receive it back in the mic?

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    You need to find an echo cancellation solution....this is not something that centrafuse does. Most users use a special microphone or soundcard which supports AEC.

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    I've seen the andrea mic (maybe on mo-co-co or maybe store.mp3car) with a little soundcard and the mic. Would this solution work? I'm currently using a noise cancellation mic designed for a mini-tape recorder. it sounds very clear though.
    and what is "AEC". (i'm guessing automatic Echo Cancellation)
    thanks for the input!

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    acoustic echo cancellation...and yes thats one solution. Keep in mind though, that if you use that method you will need to use that same usb sound card for your output or it doesn't work (limited to stereo output).

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    Isn't an in-circuit echo canceler needed?
    Mics have noise canceling, but that cancels OTHER noise (background) - not what it is supposed to pick up. (Obviously?)

    I can't see that a mic can pick up and cancel its own signal as delayed by other components (except via very complex techniques).

    Noise & echo cancelers are otherwise inversions of themselves fed back into the original signal, or elsewhere with a delay in case of echos.
    Often OpAmps are used - it's a mixing of inverted and non-inverted signals.

    Noise is usually easy - it's merely a matter of the correct gain.
    Same with echo, but the delay needs matching too.

    Usually is easier to prevent the echo - often through proper impedance matching.
    Echo canceling can be tricky as many satellite comms users know (as if their telephone & newscast interview delays weren't annoying enough!), but the odd cable and optic comms may suffer too.

    PS - regards to ChundaBay. I spent a week there last millennium.

    PPS - I realise acoustic feedback can be a bit different....

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    The echo canceling is done on the audio driver level....

    it runs algorithms comparing input to output, calculates the delay constant and removes the echo. The noise cancelling stuff is all audio processing over my head though.

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    justchat; now when you say the same soundcard for the output, you must mean the audio output in the phone settings in centrafuse correct? I guess that I'd use the onboard sound as I currently am and set the sound card solely for the mic input and phone output. makes sense. you'd think centrafuse would have dealt with that issue in the software, seems like a pretty huge bug to me!


    OldSpark; for what reason did you visit my frozen region of the earth so very long long ago?

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    CF is relying on IVT to implement the echo cancellation. no ETA on the new bluetooth stack. Many people are using the Phoenix SOHO to remove all echo. Unfortunately, it costs about $100.

    I'm using my onboard mic with EC for now. There's still a little echo, but it's not bad.

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    Quote Originally Posted by thunderbay View Post
    justchat; now when you say the same soundcard for the output, you must mean the audio output in the phone settings in centrafuse correct? I guess that I'd use the onboard sound as I currently am and set the sound card solely for the mic input and phone output. makes sense. you'd think centrafuse would have dealt with that issue in the software, seems like a pretty huge bug to me!
    Yea you could do that.

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    Alas the soundcard has the "complex processing" I mentioned for echo....
    DSP makes life so much easier - not that I've touched it for over 20 years!

    Quote Originally Posted by thunderbay View Post
    OldSpark; for what reason did you visit my frozen region of the earth so very long long ago?
    Lucky enough to meet a Kunuk traveling out far north last millennium.

    Despite having a great and memorable time, we still keep in touch.
    (Our memories may get a bit vague in front of his family though!)

    I visited him whilst at his (former?) home town of Montreal. Then drove crosscountry with his family to their hometown of Thunderbay.

    Ah yes, Canada - it isn't just the Camp or Dell's maple syrup I like (nor that you too eat your national emblem)!

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