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Communication System Using Time Division Multiplex

IP.com Disclosure Number: IPCOM000086367D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 44K

Publishing Venue

IBM

Related People

Taub, DM: AUTHOR

Abstract

A time-division-multiplex (TDM) communications system is described in which an exchange controls a number of area adapters on a main loop. Each area adapter serves a local loop into which devices may be plugged. Each area adapter includes an analog shift register which operates on local loop signals at a low frequency and on the main loop at a high frequency.

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Communication System Using Time Division Multiplex

A time-division-multiplex (TDM) communications system is described in which an exchange controls a number of area adapters on a main loop. Each area adapter serves a local loop into which devices may be plugged. Each area adapter includes an analog shift register which operates on local loop signals at a low frequency and on the main loop at a high frequency.

As shown in Fig. 1, area adapters Al to Aq are located on a main loop which may be a few kilometers in length. The main loop starts and ends at an exchange which controls the system. The exchange transmits a succession of minor frames consisting of a synchronizing signal and area slots S1 to Sq.

A local loop serves terminals in a predetermined area. The loop is formed of two conductor pairs, one end of each is connected to an associated area adapter and the terminals are in shunt across the two pairs. An area adapter includes an analog shift register with switches, as shown in Fig. 2, to place the shift register in series with the main loop or in series with the local loop, as shown in Fig. 1. The analog shift register contains typically six positions to accommodate one system slot and five channel slots. Each of the five channel slots is associated with one active terminal in the area, and the assembly of five channel slots and one system slot form an area slot.

When an area slot S1 reaches area adapter A1 the switches are set so that area slot S1 passes into the shift register, while the contents of the shift register are shifted on to the main loop. Subsequently the contents of the five channel slots are sent to five terminals on the main loop, a particular terminal "knowing" which...