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    Active noise cancellation system with split digital filter
    1.
    发明专利
    Active noise cancellation system with split digital filter 未知

    公开(公告)号：GB2465064A

    公开(公告)日：2010-05-12

    申请号：GB0919236

    申请日：2008-06-16

    Applicant: WOLFSON MICROELECTRONICS PLC

    Inventor： AL-NAIMI KHALDOON ,  MAGRATH ANTHONY JAMES ,  SIBBALD ALASTAIR

    IPC: G10K11/178

    Abstract: A noise cancellation system 24 has an input for a digital signal having a first sample rate. The digital filter 44 is a split filter composed of a fixed filter 80 and an adaptive high-pass filter 82, which are connected in series to the input in order to receive the digital signal. The fixed filter 80 is preferably an IIR filter. Control circuitry 54 generates at least one control signal, based on the input digital signal, wherein the control signal is applied to the adaptive high-pass filter 82 so as to control a cut-off frequency of the filter 82. A decimator 90 is preferably included to generate a signal at a second, lower sample rate and apply it to the control circuitry 54. This arrangement is suitable for both feedforward and feedback type noise cancelling systems.

    Noise cancellation system with adaptive filter and two different sample rates
    2.
    发明专利
    Noise cancellation system with adaptive filter and two different sample rates 未知

    公开(公告)号：GB2455828A

    公开(公告)日：2009-06-24

    申请号：GB0811001

    申请日：2008-06-16

    Applicant: WOLFSON MICROELECTRONICS PLC

    Inventor： AL-NAIMI KHALDOON ,  ALCOCK ROBERT DAVID

    IPC: G10K11/178

    Abstract: The system and method comprising: an adaptive filter 44 for receiving a digital noise signal 40 at a first sample rate and for generating a noise cancellation signal; and control circuitry 54, for generating a control signal at a second sample rate for application to the adaptive filter so as to adjust a filter characteristic. The second sample rate is lower than the first sample rate but is higher than a Nyquist sampling rate required to sample signals up to a desired cut-off frequency within the audio frequency range. The system may employ analog-digital converters 42 if the signal sources are not digital, and may use a decimator 52 to reduce signal sample rates. The first sample rate may vary from 100 kHz to over 1 MHz and the second sample rate from 50 kHz to less than 2 kHz. The system may find application in mobile phones, headphones, earphones etc..

    Active noise cancellation system with split digital filter
    3.
    发明专利
    Active noise cancellation system with split digital filter 未知

    公开(公告)号：GB2455821A

    公开(公告)日：2009-06-24

    申请号：GB0810994

    申请日：2008-06-16

    Applicant: WOLFSON MICROELECTRONICS PLC

    Inventor： AL-NAIMI KHALDOON ,  MAGRATH ANTHONY JAMES ,  SIBBALD ALASTAIR

    IPC: G10K11/178

    Abstract: A noise cancellation system 24 has an input for a digital signal having a first sample rate. The digital filter 44 is a split filter composed of a fixed digital filter 80 and an adaptive digital filter 82. Control circuitry 54 generates at least one control signal, based on the input digital signal, for the adaptive filter 82 so as to control a characteristic of the filter. This arrangement is suitable for both feedforward and feedback type noise cancelling systems (figs 2, 3).

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