Measurement apparatus for full-duplex two-wire transmission interface

摘要

The apparatus (29) is connected to the interface (2) of a two-wire line (1) terminated with a transformer (6). A fork switch (5) and an integrated interface component (3). This termination is simulated by a network (8) connected between two high-impedance differential amplifiers (9,13). The amplified output is subtracted (15) from that of an additional amplifier (17) connected to the interface. The difference signal representing the return from a line or network termination (7) is differentiated (19) for comparison (25) with a fixed threshold.