Test arrangement for communication paths in time-division multiplexed switching systems

摘要

An arrangement is described for testing a communication path to a 2-wire analog line through a time-division multiplexed switching system, wherein each analog line is coupled to the system by a hybrid circuit which provide separate transmit and receive paths. A digital tone source is coupled to a time-division bus of the system such that the digital tone source transmits signals toward the line on the receive path. A ring relay associated with the line is operated to produce an open circuit condition between the hybrid circuit and the line. The open circuit alters the transhybrid loss of the hybrid circuit such that the signals on the receive path are reflected back toward the time-division bus on the transmit path. A digital tone detector is coupled to the transmit path such that the reflected signals may be detected.