METHOD AND APPARATUS FOR DELAY-LINE TIME-DOMAIN REFLECTOMETRY

摘要

An apparatus for testing a telephone line (12) includes a charge generator (4) for selectively charging a line capacitor (16) formed by the physical relation of at least two electrically conductive leads (8, 10) of the telephone line (12) to a predetermined DC voltage. A line clamp (6) selectively connects the leads (8, 10) together and a return detector (18) receives a discharge pulse (22) produced by discharge of the line capacitor (16) in response to the line clamp (6) connecting the leads (8, 10) together. The return detector (18) detects an end-of-line pulse (28) and/or a bridged-tap pulse (32) superimposed on the discharge pulse (22) and outputs an analog return signal as a function thereof.