Browse Prior Art Database

Personal Computer-Adapter Card Interface for Monitoring a Telephone Line

IP.com Disclosure Number: IPCOM000061527D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Einkauf, MA: AUTHOR [+5]

Abstract

An interface to a signal processing Personal Computer (PC) adapter card to monitor a telephone line for signals during a call is described. Most common push-button telephones transmit digits using tone pairs, called "dual tone multiple frequency" (DTMF). Line Monitoring is a function set of the interface that provides the capability to detect these DTMF tones and, for each DTMF tone, to signal the interface with the generation of a DTMF interrupt condition. The processing required to perform full DTMF signal detection under difficult conditions (noisy, long distance lines, for example) may consume a significant portion of the processing power available to the implementation, such that full DTMF detection cannot be performed at the same time as other speech processing functions without adversely affecting them.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

Page 1 of 1

Personal Computer-Adapter Card Interface for Monitoring a Telephone Line

An interface to a signal processing Personal Computer (PC) adapter card to monitor a telephone line for signals during a call is described. Most common push-button telephones transmit digits using tone pairs, called "dual tone multiple frequency" (DTMF). Line Monitoring is a function set of the interface that provides the capability to detect these DTMF tones and, for each DTMF tone, to signal the interface with the generation of a DTMF interrupt condition. The processing required to perform full DTMF signal detection under difficult conditions (noisy, long distance lines, for example) may consume a significant portion of the processing power available to the implementation, such that full DTMF detection cannot be performed at the same time as other speech processing functions without adversely affecting them. In practice, this means that the remote user may not be able to interrupt (i.e., stop) an output message (either text-to- speech or speech playback) with any random button on the telephone. For this reason, a specific DTMF detect facility is provided, '* DTMF,' which is only capable of detecting the DTMF tone from the '*' button on the telephone. This detection facility, which takes considerably less processing power, will detect the '*' even when there is other activity on the line. However, in order to ensure that the remote user can interrupt an output message, the user should be encouraged to hold the...