Abstract: A carrier system is described in which a number of pulse encoded signals are multiplexed on a single transmission and demultiplexed and decoded at a remote terminal for distribution to a number of receivers at that location. A similar multiplex system uses a separate return pair of transmitting signals in the opposite direction. The multiplexed signals on each transmission line are framed by means of a framing pulse in each frame having a value which insures a preselected parity for each frame. To make sure that parity discrepancies will exist for other pulse positions even under all "1s" and all "0s" conditions, a second bit position is filled with a randomly-valued bit.

Abstract: A closed loop transmission system is described in which a plurality of stations have access to each loop to write messages into and read messages from standard-sized message blocks transmitted around the loop. One station in each loop provides regeneration of all message blocks. The various loops are interconnected by switching stations which respond to address information at the head of each message block to selectively switch the block to the interconnected loop. The next required address is always substituted for the current address to simplify address recognition. Alternate and redundant routing are also provided for.