公开(公告)号：US4115668A

公开(公告)日：1978-09-19

申请号：US792096

申请日：1977-04-29

申请人： Ambroz K. Skrovanek ,  Fred E. Clark, Jr.

发明人： Ambroz K. Skrovanek ,  Fred E. Clark, Jr.

IPC分类号： H04B3/20

CPC分类号： H04B3/20

摘要： An interface unit for a four wire telephone circuit includes an echo suppressor. A filter circuit is connected to the transmit line drop side to detect voice and SF signals and to selectively couple a regenerated SF signal and the voice signal to the line side of the transmit line. A passive filter is selectively coupled to the receive side to attentuate voice echo but bypass SF signals.

摘要翻译： 用于四线电话电路的接口单元包括回波抑制器。 滤波器电路连接到发射线路降侧，以检测语音和SF信号，并将再生的SF信号和语音信号选择性地耦合到发射线的线路侧。 无源滤波器选择性地耦合到接收侧以注意声音回声但是旁路SF信号。