Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Telephone Line Scanning System

IP.com Disclosure Number: IPCOM000095259D
Original Publication Date: 1965-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Beausoleil, WF: AUTHOR [+2]

Abstract

The telephone line scanning system is based upon the fact that knowledge, at a given instant, of the open or closed status of both sides of a subscriber's transformer defines the subscriber's status immediately.

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 87% of the total text.

Page 1 of 2

Telephone Line Scanning System

The telephone line scanning system is based upon the fact that knowledge, at a given instant, of the open or closed status of both sides of a subscriber's transformer defines the subscriber's status immediately.

Thus, should an open circuit be indicated by a 0 and a closed circuit by a 1, and considering from left to right the telephone line and the link circuit to the switching network, the four following subscriber's statuses can be found. 00 free

10 new call

11 busy

01 dialing or hang-up.

As the scanning information has to be processed only in the case of new call, either dialing or hang-up status, this system selects the two corresponding informations 01 and 10. These only are sent to the processor.

A Subscriber Address Register, sequentially stepped, simultaneously controls the scanning of both sides of the addressed subscriber's transformer through a Line Selection Matrix and a Link Selection Matrix. The resulting scanning information is, respectively, collected by a Line Status Detector and a Link Status Detector. Such information is sent to logic circuits which detect either 01 or 10. When either one of these two combinations is detected, the information is sent to the Processor, through an And gate controlled by the Subscriber Address Register.

For a 1000 line PBX in which each line is scanned every 15 ms, the usual scanning rate, and assuming one dialing operation per second, the processor only has to process about 75 item...