LINE INTERFACE APPARATUS AND METHOD FOR ISOLATING DATA TERMINAL EQUIPMENT FROM THE LINE

摘要

An improved isolation circuit for protecting data communications equipement from high voltages on a transmission line has two mixers (124, 130). The first dual balanced mixer (DBMX) (124) translates a data signal on the transmission line (30) to a high frequency and is coupled with an isolation circuit (128) to the second DBMX (130). The second DBMX (130) then translates the output of the first DBMX (124) to an isolated data signal with the same frequency content as the original data signal.