Detection of ground or loop start configuration in telephone loop signalling circuit

摘要

A telephone loop signalling circuit, which automatically replicates either a loop start or a ground start configuration under virtually all operating conditions of the telephone line including those which have heavily induced power line voltages. The circuit utilizes a bias network connected to the central office side of the line together with a plurality of detectors which coact with logic circuitry to differentiate between the two configurations under these widely varying conditions.