LINE TERMINATING APPARATUS

摘要

To provide facilities to handle many different types of customer line which may be connected to a telephone exchange each line circuit includes adjustable terminating and amplifying devices responsive to signals received from a control unit to adjust (e.g.) line terminating impedance and gain. The line circuits are grouped together with associated group multiplexers and address decoding facilities. Stored parameters held by the control unit may be dynamically updated in response to changes in line condition detected by power feed circuitry in the line circuits, the power feed circuitry being arranged to provide a constant current feed to the line pair and to send AGC signals reflecting increased or decreased line resistance by way of the respective group multiplexer to the control unit. Other facilities of the apparatus include provision of calling signals to line and the provision of subscriber private metering (SPM) signals. Each pulse of dialled digits is detected in the line circuit and multiplexed to the control unit which accumulates the dialled digits forwarding each complete digit to the communications exchange.