公开(公告)号：US5973516A

公开(公告)日：1999-10-26

申请号：US139011

申请日：1998-08-24

Applicant: Duncan James Bremner ,  Ray Allen Reed

Inventor： Duncan James Bremner ,  Ray Allen Reed

IPC: H03K5/1534 ,  H04M3/22 ,  H03K5/153

CPC classification number: H03K5/1534 ,  H04M3/2272

Abstract: A subscriber line interface circuit which includes a transient signal detector with temporal hysteresis. During steady state operation, the drive current for the subscriber loop allows the loop to respond to changes in loop conditions according to a steady state time constant of the loop filter. Upon detection of a line voltage transient which exceeds a predetermined threshold in either a positive or negative direction, the filter time constant is significantly reduced (e.g., 100:1) and held at such reduced value following the initial transient and for a predetermined time period after the line voltage has fallen back below such predetermined threshold. This allows the transient conditions to be fully compensated prior to resetting the filter time constant back from the lower transient value to the higher steady state value.

Abstract translation: 一种用户线接口电路，其包括具有时滞的瞬态信号检测器。 在稳态操作期间，用户环路的驱动电流允许环路根据环路滤波器的稳态时间常数响应环路条件的变化。 在正或负方向上检测到超过预定阈值的线路电压瞬变时，滤波器时间常数显着降低（例如，100:1），并且在初始瞬变之后保持在这样的减小值，并且在预定时间段 在线路电压下降到低于该预定阈值之后。 这使得在将滤波器时间常数从较低的瞬态值恢复到较高的稳态值之前，可以完全补偿瞬态条件。