SUBSCRIBER CIRCUIT TEST METHOD

摘要

PURPOSE:To conduct a test corresponding to the titled circuit without using a line concentrator for testing by disconnecting a balanced connection network in the subscriber circuit, terminating the DC circuit side by high resistance and reflecting a signal from the reception side at a 2-wire part. CONSTITUTION:An addition/subtraction circuit 7 corresponding to the balanced connection network of the subscriber circuit 2 is disconnected from an input VR of an amplifier 6 by opening a changeover switch 11 for testing and both terminals of a subscriber line drive current source 3 are switched from the connection to an impedance 1 incorporating the subscriber line and a subscriber terminal equipment into high resistance 12 to apply a DC power of a 2-wire side by using a changeover switch 10 for testing. A PCM pattern DR is inputted to a digital/analog conversion circuit in this state, a PCM pattern DS of an output of an analog/digital conversion circuit 8 is detected to measure the characteristic of the subscriber circuit 2.