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Encoding Serial Data for Error Minimization and Error Recovery

IP.com Disclosure Number: IPCOM000080181D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Webb, GT: AUTHOR [+2]

Abstract

Digital data is recorded according to an 8-1/2 bit encoding technique, to facilitate recovering from loss of synchronization and eliminating potential playback errors resulting from certain combinations of bits.

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Encoding Serial Data for Error Minimization and Error Recovery

Digital data is recorded according to an 8-1/2 bit encoding technique, to facilitate recovering from loss of synchronization and eliminating potential playback errors resulting from certain combinations of bits.

With seven bits being used per character, the bits making up each character are phase encoded in a conventional manner. For defining each character, an additional 1-1/2 bit times are added to a normal one-bit time between bits 7 and 1 and encoded such that a corrective flux reversal will occur at 1/2T (where T = normal intracharacter bit time). A transition must not occur at T (normal data time), another transition will occur at 1-1/2T, a corrective flux reversal may occur at 2T, and the one bit of the next character must occur at 2-1/2T.

Digital data separation is used to define corrective flux reversals and data bits, and any flux transitions outside the limits defined are considered errors. Bit 7 is now uniquely defined as being the only data bit which will not have another data bit occur one-bit time later. Additionally, there is a corrective flux reversal/data bit phase change between successive characters, which is useful in regaining synchronization.

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