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Ring Indicator Detection Logic Circuit

IP.com Disclosure Number: IPCOM000073436D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Froemke, JW: AUTHOR

Abstract

This circuit is used with a binary synchronous communications adapter that is used in connection with a particular type of data set (Swedish GE2002A, Standard Radio and Telefon, Barkarby, Liveden) providing an erroneous 16-second RING INDICATOR signal or glitch after disconnecting from the line providing incoming calls, and the circuit distinguishes between a valid RING INDICATOR signal as distinguished from the 16-second glitch. In addition, as a new call comes in during the period of the glitch, the circuit causes the call to be answered.

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Ring Indicator Detection Logic Circuit

This circuit is used with a binary synchronous communications adapter that is used in connection with a particular type of data set (Swedish GE2002A, Standard Radio and Telefon, Barkarby, Liveden) providing an erroneous 16- second RING INDICATOR signal or glitch after disconnecting from the line providing incoming calls, and the circuit distinguishes between a valid RING INDICATOR signal as distinguished from the 16-second glitch. In addition, as a new call comes in during the period of the glitch, the circuit causes the call to be answered.

The circuit monitors the RING INDICATOR line 15 for an OFF to ON transition occurring after the Binary Synchronous Communications Adapter (BSCA) is enabled; and, therefore, the BSCA need only be disabled for two seconds. Any off to on transition of the ring indicator line is then considered to be a valid incoming call and is automatically answered.

Initially, the BSCA line 21 is disabled, forcing a set condition within flip-flops 1 and 2 while the ring indicator latch 3 is reset. If the ring indicator signal in line 15 is OFF (+) when the BSCA is enabled, the first negative transition of the SAMPLING STROBE signal in line 16 will toggle flip-flop 1 into reset condition. The second negative transition of the sampling strobe in line 16 will toggle flip- flop 2 in reset condition. Both flip-flops 1 and 2 will remain in their reset conditions while the ring indicator line 15 is OFF (+). When a call comes in, the ring indicator signal on line 15 turns from of...