Browse Prior Art Database

Asynchronous Data Transmission

IP.com Disclosure Number: IPCOM000089310D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Sommerfield, EH: AUTHOR

Abstract

This concerns a system for digital data transmission having decreased probability of ambiguous or erroneous reception. It is based upon utilization of signal parameters of the slow scan TV (SSTV) signaling method which amateur radio operators use ordinarily for communicating display image (noncoded) information. The parameters for signaling in the SSTV system are: Horizontal synch is represented by a 1200-hertz signal having a duration between 5 and 7 milliseconds. Vertical synch is manifested by a 1200-hertz signal persisting for more than 30 milliseconds. Maximum "white" and "black" levels of video information (grey scale extremes) are manifested respectively by 2300-hertz and 1500-hertz signals persisting for predetermined portions of a line scan period (line frame).

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Asynchronous Data Transmission

This concerns a system for digital data transmission having decreased probability of ambiguous or erroneous reception. It is based upon utilization of signal parameters of the slow scan TV (SSTV) signaling method which amateur radio operators use ordinarily for communicating display image (noncoded) information. The parameters for signaling in the SSTV system are: Horizontal synch is represented by a 1200-hertz signal having a duration between 5 and 7 milliseconds. Vertical synch is manifested by a 1200-hertz signal persisting for more than 30 milliseconds. Maximum "white" and "black" levels of video information (grey scale extremes) are manifested respectively by 2300-hertz and 1500-hertz signals persisting for predetermined portions of a line scan period (line frame). The basic line frame frequency is 15 hertz (basic line frame duration is 1/15 second or 66.67 milliseconds). Consider now the possibility of utilizing a subset of these parameters for transmission of digital (nonimage) data as follows: Mark bit values represented by 2133-hertz pulse signals persisting for 6.67 milliseconds (1/10 of a "line frame"). Space bit values represented by 1600-hertz pulse signals having durations of 6.67 milliseconds. Synch manifested by 1200- hertz pulse signals persisting for 13.3 milliseconds (2/10 of a "line frame"). Signal format: synch pulse, 8-bit (mark/space) pulses, synch pulse, 8-bit pulses,....; i.e., one byte of information (8 bit...