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[TMDSLCDK138] OMAP-L138 Development Kit for Active Noise Cancellation application

Anwar Koshakji
Prodigy 30 points
Other Parts Discussed in Thread: OMAP-L138, OMAPL138

Hi everybody,

I want to set up a system for Active Noise Cancellation. The very first application is the classical 1D duct where a known plane wave is cancelled.

For this purpose, it seems that the DSP board OMAP-L138 DSP+ARM9 Development Kit is one of the best low-cost choice.
Do you have any suggestion about which microphones and which speakers are better to use? Do I need preamplifiers/amplifiers or they are integrated in the DSP board?

Thank you in advance.

Anwar K.

  • 0
    TI__Guru**** 161600 points
    Hi,

    Do you have any suggestion about which microphones and which speakers are better to use?

    Do you need a recommendation for a specific vendor? If so, there isn't such requirement, the device should work with most of the available microphones/speakers.

    Do I need preamplifiers/amplifiers or they are integrated in the DSP board?

    The microphones should work without any preamplifiers. As for the speakers, you may need external an external amplifier.

    Best Regards,
    Yordan
  • 0 in reply to Yordan Kovachev
    Prodigy 30 points

    Hi Yordan,

    Thank you for your answer.

    I found these speakers on the market: http://it.rs-online.com/web/p/altoparlanti-miniatura/7755031/
    Do you think they will be fine for work with this device? 
    Can you suggest us some low cost external amplifier?

    And here the microphones: http://it.rs-online.com/web/p/microfoni-a-condensatore/7243125/
    Do they work fine with this DSP board without preamplifiers?

    Thank you so much in advance!

    Anwar K.

  • 0 in reply to Anwar Koshakji
    TI__Guru** 116170 points
    Anwar,

    Please note that LCDK doesn`t configure MIC BIAS on the board so you need a microphone that is externally powered and configuration of the AIC codec to get this to work. We had used a setup for AEC setup with this board and we used Curve series speaker CA-2050 and used Omni directional Microphones from Radio shack.

    And the underlying software was modified version of the MCASP loopback code in starterware. You can look at this AEC design using OMAPL138 here:
    www.ti.com/.../TIDEP0071

    Regards,
    Rahul
  • 0 in reply to Rahul Prabhu
    Prodigy 30 points
    Thank you Rahul, very interesting answer. We are taking a deep look on it.

    We are going to set up the ANC system by using 2 microphones (one for catching the input noise and one for the error evaluation at the end of the line) and 2 speakers. But I saw, on the datasheet of OMAP-L138 Development Kit that there are just 1 Microphone port and 1 Audio Out port.

    Can you confirm me that is possible to use all these devices simultaneously?
  • 0 in reply to Anwar Koshakji
    TI__Guru** 116170 points
    Yes, there is just one Microphone port and 1 audio out put on the LCDK, Either you can use 2 LCDK boards for the design. the other option would be to use a stereo splitter and hook up 2 microphones to mono channels for input. I dont think this is ideal but you can experiment with it to see if this works for your setup.

    Please note many of the platforms that we provide are not designed for multi-microphone input but if you are looking for a platform to prototype that has multiple audio in and audio Out, you can also consider the C6747 EVM which has a multi-channel audio input daughter card and codecs that support higher sampling rate. Note, there are meant for performance audio application and not neccessaarily for multi-microphone inputs.

    Regards,
    Rahul