Browse Prior Art Database

Line Attachment Circuit

IP.com Disclosure Number: IPCOM000083729D
Original Publication Date: 1975-Jul-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 77K

Publishing Venue

IBM

Related People

Boisseau, M: AUTHOR [+3]

Abstract

The figure shows three private branch exchanges XA, XB and XC, in which a connection has been made from extension A of XA to extension C of XC through tie line AB, the XB network and tie line BC.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 55% of the total text.

Page 1 of 3

Line Attachment Circuit

The figure shows three private branch exchanges XA, XB and XC, in which a connection has been made from extension A of XA to extension C of XC through tie line AB, the XB network and tie line BC.

Each PBX network is of the one-wire switching type (and 2-wire interfaces through the line transformers). Each tie line is a four-wire line, i.e., a 2-wire line for each direction.

From a switching standpoint, a connection of the type represented in Fig. 1 is made as follows:

- In XA, extension A is connected to tie line :AB (i.e., 2-wire lines AB1 and AB2), through the XA network, and a circuit KA2 which converts the network output 2-wire line OA into a 4-wire line;

- In XB, tie line AB is connected to tie line BC through the following circuits:

o A first circuit KB1, which connects the 2-wire lines AB1, AB2 of tie line AB to network input lines IB1 and IB2, respectively;

o The XB switching network, which connects input lines IB1 and IB2 to output lines OB1 and OB2, respectively,;

o A second circuit KB2, which connects output lines OB1 and OB2 to the 2- wire lines BC1 and BC2 of tie line BC.

- In XC, tie line BC is connected to extension C through a circuit KC1 converting the 4-wire line of BC into a 2-wire line (circuit similar to KA2), and the switching network.

In fact, there are three types of specific circuits to be provided to the PBX's:.

o KA2 (or KC1) type, the function of which is to provide for a 4-wire/2-wire conversion;

o KB1 type, the function of which is to provide for a crossed-connection between two pairs of 2-wire lines (this crossed-connection is made for addressing convenience);

o KB2 type, the function of which is to provide for a direct connection between two pairs of 2-wire lines.

Because it is desirable that any of the PBX's be able to act as a terminal PBX or a transit PBX, each PBX must incorporate circuits of the above three types. In fact,...