Patent ID: 6064422
Filing Date: 2000-05-16
Classification: H04N

Abstract:
A video switch comprising:a first plurality of input line terminations each having the form of a conventional, modular telephone jack that is connectable to an unshielded twisted pair of telephone wires,a separate balanced input transmission line connected to each of said input line terminations,a separate balanced-to-unbalanced, single-ended input impedance conversion circuit connected to each of said balanced input transmission lines, wherein said input impedance conversion circuits provide automatic impedance equalization for the line lengths of unshielded twisted pairs of telephone wires coupled to said input line terminations,a separate unbalanced input transmission line connected to each of said input impedance conversion circuits,a cross-matrix switch formed of an array of a second plurality less than said first plurality of single-ended, cross-matrix switching chip circuits connected to said input transmission line and coupled in parallel in pairs in which one chip circuit in each pair transmits in a forward direction and the other in each pair transmits in an opposite, reverse direction, said cross-matrix switch further including a bus interface and control logic circuit, a parallel control interface port, and a serial control interface port for connection to a computerized control system,a plurality of unbalanced output transmission lines, equal in number to said first plurality of input line terminations, connected to said cross-matrix switching chip circuits to provide separate outputs therefrom,a separate unbalanced-to-balanced impedance matching and line drive circuit connected to each of said unbalanced output transmission lines,a separate balanced output transmission line connected to each of said unbalanced-to-balanced impedance matching and line drive circuits, andseparate output line terminations connected to each of said balanced output transmission lines, each of said output line terminations having the form of a conventional, modular telephone jack that is connectable to an unshielded twisted pair of telephone wires.