Switching of balanced line-pairs in a cable management system with reduced number of crosspoint switches

摘要

A cable management system provides routing of wired services between service lines (16) and user lines (18). Each service line (16) enters the cable system at a service termination unit circuit card (22) which also holds a portion of a crosspoint switch matrix (228). Each user line (18) enters the system at a line termination unit circuit card (20). The service termination unit circuit cards (22) are all mounted to connectors on a first side of a centerplane board (24) and the line termination unit circuit cards (20) are mounted to connectors on the other side of the centerplane board (24). Pins extending through the centerplane board (24) interconnect the connectors on the opposed sides of the centerplane board (24) so that any service line (16) can be connected to any user line (18). A system controller card (26) mounted to the centerplane board (24) communicates with the circuit cards via a bus on the centerplane board (24). When the service lines and user lines (16,18) are made up of balanced line-pairs (218, 224, 222, 226), in order to reduce the number of crosspoint switches (238) in the crosspoint switch matrix (228), the differential signals on the balanced line-pairs (218, 226) are converted to single-ended signals on individual lines (240). The individual lines (240) are switched through the matrix (228) and the signals thereon are then reconverted back to differential signals on balanced line-pairs (222, 224).