The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 31, 1990
Filed:
Nov. 14, 1988
Arvind M Patel, San Jose, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method and apparatus for processing, in a signal processing channel, digital values corresponding to a digitized incoming analog signal representative of coded binary data. Using a state-dependent sequence detection algorithm appropriate functional expressions of digital sample values are precomputed at each cycle of the digitizing clock for a preselected number of bits ahead of the current bit. Preselected ones of these expressions are compared against corresponding thresholds to provide respective binary decision outputs that, with state values corresponding to the current state, determine state values for the next state and decode one bit of coded binary data at each clock cycle. Programmed values generated for the thresholds may be adaptively modified according to changes in sample values in the incoming analog signal relative to corresponding expected sample values. Different thresholds are used for positive and negative phases of the analog signal shape to accommodate signal shape asymmetry. Because the decoder is programmable, threshold constants at different tracks or bands of tracks in a disk file can be changed to optimize performance at all tracks of the file.