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Bidirectional Loop for Digital Transmission

IP.com Disclosure Number: IPCOM000077610D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Besseyre, J: AUTHOR [+2]

Abstract

In application of digital circuits to telephony, it is possible to consider a digital telephone set wherein voice signals are digitally encoded through PCM or delta modulation. In this case a plurality of telephone sets may be connected in a loop configuration. This configuration has a major drawback in that the loop is inoperable, when a failure occurs somewhere in the wire or in the telephone set. This drawback is eliminated by the configuration represented in Figs. 1 and 2.

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Bidirectional Loop for Digital Transmission

In application of digital circuits to telephony, it is possible to consider a digital telephone set wherein voice signals are digitally encoded through PCM or delta modulation. In this case a plurality of telephone sets may be connected in a loop configuration. This configuration has a major drawback in that the loop is inoperable, when a failure occurs somewhere in the wire or in the telephone set. This drawback is eliminated by the configuration represented in Figs. 1 and 2.

As shown in Fig. 1, a plurality of a telephone sets comprising two pairs of driver-receiver D-R and a switch arrangement are connected in series on a two- wire bidirectional loop to a private exchange PBX. Four telephone sets TS1-TS4 are represented in Fig. 1.

Codes messages comprising the addresses of the desired telephone sets, clocks signals and data are transmitted on lines L1 and L2 through the drivers D1 and D2 at the output of PBX. The messages are received by the receiver at the input of telephone set TS1-TS4. For example as represented in Fig. 1, message coming from D1 on line L1 is received by receiver R1 of TS1, the address is checked and if it is not assigned to TS1, the message is transmitted by driver D1 of TS1 to TS2, and so on, until it reaches the desired telephone set.

If no failure has occurred on the loop configuration as represented in Fig. 1, clocks signals transmitted on lines L1 and L2 are present on terminals C1 and C2 of...