Telephone subscriber loop test system

Abstract From the Canadian patent

A method of locating faults in a telephone system including the steps of connecting antiparallel rectifying switches (ARS's) that inhibit alternating current (A.C.) flow in one direction but not the other between subscriber equipment and respective telephone company lines, applying an A.C. test signal to a telephone company line and measuring a resulting signal and determining whether a fault is on the telephone company line or customer equipment based upon the resulting signal. Also disclosed is an ARS that includes a first input and output, a second input and output, and paths between respective inputs and outputs providing low turn-on thresholds in one direction between respective inputs …