公开(公告)号：US5278900A

公开(公告)日：1994-01-11

申请号：US680485

申请日：1991-04-04

申请人： Petrus J. Van Gerwen ,  Hendrik J. Kotmans ,  Franciscus A. M. van de Laar

发明人： Petrus J. Van Gerwen ,  Hendrik J. Kotmans ,  Franciscus A. M. van de Laar

IPC分类号： H04B3/23 ,  H04M9/08

CPC分类号： H04B3/234

摘要： A digital echo canceller has a receive path (2) and a send path (3) and comprises combining apparatus (10) for forming a send output signal [r(k)] as the difference between the signal [z(k)] applied to the send input (SI) and a replica signal [e(t)] used for cancelling an additive echo signal [e(k)] at the send input (SI) that has developed in response to a receive input signal [x(k)] applied to the receive input (RI), which echo canceller at least includes transforming apparatus (13, 15) for transforming the receive input signal [x(k)] and the send output signal [r(k)]; transforming apparatus (14) for transforming the replica signal [e(k)]; a digital adaptive filter (9) which has a number of filter coefficients for generating the replica signal [e(t)] in response to the receive input signal [x(k)] and the send output signal [r(k)], adaptation apparatus (12) for determining for each block m, adaptation components [A(p;m)] for each of the filter coefficients [W(p;m)] in response to the receive input signal [x(k)] and the send output signal [r(k)]; controllable gate means (17) for selectively passing the adaptation components [A(p;m)] to the adaptive digital filter (9); control apparatus (25-28, 21-24, 16) for determining respective levels of the send output signal [r(k)] and the receive input signal [x(k)] and for generating a control signal for the gate apparatus (17) in response to the levels thus determined, which control signals depend in a predetermined manner on the difference between the levels concerned.

摘要翻译： 数字回声消除器具有接收路径（2）和发送路径（3），并且包括用于形成发送输出信号（r（k））的组合装置（10）作为施加的信号（z（k））之间的差 用于响应于接收输入信号而产生的发送输入（SI），用于消除加性回波信号（e（k））的发送输入（SI）和复制信号（e（t））（x（ k）），该回波消除器至少包括用于变换接收输入信号（x（k））和发送输出信号（r（k））的变换装置（13,15）; 变换装置（14），用于变换复制信号（e（k））; 响应于接收输入信号（x（k））和发送输出信号（r（k）），具有用于产生复制信号（e（t））的滤波器系数的数字自适应滤波器（9） 适应装置（12），用于响应于接收输入信号（x（k））为每个块m确定每个滤波器系数（W（p; m））的适应分量（A（p; m）），以及 发送输出信号（r（k））; 用于选择性地将自适应分量（A（p; m））传递到自适应数字滤波器（9）的可控门装置（17）; 控制装置（25-28,21-24,16），用于确定发送输出信号（r（k））和接收输入信号（x（k））的各个电平，并用于产生门装置的控制信号 17）响应于如此确定的电平，哪个控制信号以预定的方式取决于所涉及的电平之间的差异。

公开(公告)号：US4903247A

公开(公告)日：1990-02-20

申请号：US210268

申请日：1988-06-23

申请人： Petrus J. Van Gerwen ,  Franciscus A. M. van de Laar ,  Hendrik J. Kotmans

发明人： Petrus J. Van Gerwen ,  Franciscus A. M. van de Laar ,  Hendrik J. Kotmans

IPC分类号： H03H17/02 ,  H03H17/08 ,  H03H21/00 ,  H04B3/23 ,  H04M9/08

CPC分类号： H04B3/237 ,  H04M9/082 ,  H04B3/234 ,  H04B3/238 ,  Y10S367/901

摘要： A digital echo canceller [1] with a good protection against double-talk comprises a first filter [9] for the echo cancellation proper, a second adaptive filter [11] for making continuously adapted filter coefficients available to the first filter [9] and gate means [15] which will only apply the adapted filter coefficients to the first filter [9] if certain conditions are satisfied. In the echo canceller [1] a specific filter combination is used, in which the first filter [9] is a time-domain programmable filter (TDPF) and the second filter [11] is a frequency-domain block-adaptive (FDAF), and further means [20,20(1)] are provided that are arranged in cascade with the gate means [15] for transforming the frequency-domain filter coefficients [W(p;m)] of the FDAF [11] into time-domain filter coefficients [w(i;m)] for the TDPF [9]. These measures result in the advantages of a negligible delay in the echo cancellation by the TDPF [9], and of the possibility to improve in a simple manner the convergence behavior of the FDAF [11] and considerably reduce its computational complexity.

公开(公告)号：US5390250A

公开(公告)日：1995-02-14

申请号：US810776

申请日：1991-12-17

申请人： Cornelis P. Janse ,  Franciscus A. M. van de Laar

发明人： Cornelis P. Janse ,  Franciscus A. M. van de Laar

IPC分类号： H04B3/23 ,  H04M9/08 ,  H04M1/58

CPC分类号： H04M9/082

摘要： An echo canceller for use in send/receive apparatus includes a frequency-domain adaptive filter which provides filter parameters to a time-domain programmable filter. The programmable filter produces a signal y(k) which is an estimate of the echo signal produced by acoustic coupling between a loudspeaker in the received path and a microphone in the send path. By subtracting this estimate from the signal produced in the send path, an output signal r(k) is obtained from the send path which is essentially free of echoes. An accurate estimate of the echo signal cannot be obtained if a send signal is present at the input of the send path. Therefore, detecting means in the adaptive filter detects whether such a send signal is present and in that case blocks the transfer of filter parameters from the adaptive filter to the programmable filter. Erroneous modification of the estimated echo signal is thereby avoided. Detection of the presence of a send signal is based on whether the ratio of the power of the signal z(k) in the send path to the power of an output signal of the adaptive filter exceeds a specific threshold.

摘要翻译： 用于发送/接收设备的回波消除器包括频域自适应滤波器，其向时域可编程滤波器提供滤波器参数。 可编程滤波器产生信号y（k），其是通过接收路径中的扬声器与发送路径中的麦克风之间的声耦合产生的回波信号的估计。 通过从在发送路径中产生的信号中减去该估计，从基本上没有回波的发送路径获得输出信号r（k）。 如果发送信号存在于发送路径的输入端，则无法获得回波信号的精确估计。 因此，自适应滤波器中的检测装置检测这样的发送信号是否存在，并且在这种情况下阻止滤波器参数从自适应滤波器到可编程滤波器的传送。 从而避免了估计的回波信号的错误修改。 发送信号的存在的检测基于发送路径中的信号z（k）的功率与自适应滤波器的输出信号的功率的比率是否超过特定阈值。