公开(公告)号：US5677987A

公开(公告)日：1997-10-14

申请号：US276617

申请日：1994-07-18

申请人： Nobuyuki Seki ,  Kazuhiro Onizuka ,  Akihisa Kawamura

发明人： Nobuyuki Seki ,  Kazuhiro Onizuka ,  Akihisa Kawamura

IPC分类号： H04B3/20 ,  H04R3/02 ,  G10L3/02 ,  G10L9/00 ,  H04B15/00 ,  H04R27/00

CPC分类号： H04R3/02 ,  H04R27/00

摘要： An A/D converter converts an analog signal to a digital signal. A plurality of cascade-connected notch filters include a first notch filter which is connected to the output of the A/D converter. A D/A converter is connected to the output of the last stage notch filter for converting a digital signal to an analog signal. The output of the last stage notch filter is connected to the input of a fast Fourier transform unit for analyzing the frequency. Analysis results of the fast Fourier transform unit are supplied to a detector. A coefficient having the same center frequency as that of a peak frequency outputted from the detector is selected from a coefficient memory and it is transferred to a second coefficient memory. Thus, the frequencies of the notch filters are set to eliminate howling.

摘要翻译： A / D转换器将模拟信号转换为数字信号。 多个级联连接的陷波滤波器包括连接到A / D转换器的输出的第一陷波滤波器。 D / A转换器连接到最后级陷波滤波器的输出端，用于将数字信号转换为模拟信号。 最后一级陷波滤波器的输出端连接到快速傅立叶变换单元的输入端，用于分析频率。 将快速傅立叶变换单元的分析结果提供给检测器。 从系数存储器中选择具有与从检测器输出的峰值频率相同的中心频率的系数，并将其传送到第二系数存储器。 因此，陷波滤波器的频率被设定为消除啸声。