Appts to test condition of electrical service line - has resistance element connected across line to present predetermined impedance

摘要

The apparatus is used to check the operability of an electrical service line, such as a telephone service line or other low voltage service line, between a test station and a telephone service installation or other electrical equipment connected to the line. This is done even in the absence of any telephone set or other electrical equipment connected to the line at the service installation. The apparatus includes an electrical device connected to the line at the service installation to receive a signal transmitted from the test station and to modify the signal returned to the test station to indicate the operability of the line, and to modify the signal to indicate the presence or removal of any telephone set or other electrical equipment connected to the line at the service installation.