Abstract: A multiplexer for multiplexing and demultiplexing signals between a low-speed network and a higher speed network includes 7 quad DSX-1 cards and 1 spare card. The spare card is connected to the DSX-1 cards to allow the spare card to automatically be switched in for one of the DSX-1 cards or to allow interface electronics on the spare card to replace selected ones of interface electronics on different DSX-1 cards simultaneously. A pair of controller cards, a primary card and a secondary card, perform M1-3 multiplexing and demultiplexing and the DS-3 framing and transceiving. The controller cards can be selected or deselected in a short time period alarms are not set off and so that the transition is hitless by electronically enabling and disabling the transceiver. The multiplexer is connectable to 2 different T-3 links to provide network redundancy. An array of relays connected either controller card to either of the T-3 links.

Abstract: A multiplexer device for multiplexing and demultiplexing signals between a low-speed network including 28 DSX-1 signals and a relatively higher speed network including a DS-3 signal. The multiplexer device includes 7 quad DSX-1 cards and 1 spare card. The spare card is connected to the other 7 DSX-1 cards in a fashion that allows the spare card to automatically be switched in for one of the DSX-1 cards or to allow interface electronics on the spare card to replace selected ones of the interface electronics on various different DSX-1 cards simultaneously. A pair of controller cards, a primary card and a secondary card, perform the M1-3 multiplexing and demultiplexing and the DS-3 framing and transceiving. The controller cards can be selected or deselected by distributed logic in a sufficiently short time period so that alarms are not set off and so that the transition is hitless. This is accomplished by electronically enabling and disabling the transceiver.