Self-Balancing Line Hybrid
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
A self-balancing technique is described for use in line hybrid circuits for interfacing electronic devices to telephone networks. The technique improves the performance of various devices, such as audio distribution systems and modems, using a single twisted-pair phone line for communications in both directions at once. The operation of this circuit relies on balancing an impedance bridge which uses the impedance of the phone line as one leg of the bridge. The circuit is divided into two portions: the analog portion at the right and the digital portion at the left. Digital samples A of the desired transmit signal are fed into a 90Œ shifter 1, such as a Hilbert transformer. The non-shifted data samples and the 90Œ shifted data samples are each multiplied by gain factors G1 and G2.