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:
Dec. 01, 1998
Filed:
Nov. 07, 1996
Christopher P Zook, Longmont, CO (US);
Neal Glover, Broomfield, CO (US);
Alan J Armstrong, Broomfield, CO (US);
Cirrus Logic, Inc., Fremont, CA (US);
Abstract
A magnetic disk storage system is disclosed wherein byte synchronization to sector data is achieved even when noise in the read channel, due for instance to a thermal asperity (TA), corrupts the primary preamble and/or sync mark fields or causes a loss of frequency or phase lock. The data sector format is modified to comprise at least one secondary sync mark in addition to the conventional primary sync mark recorded at the beginning of the data field. In this manner, when the primary sync mark becomes undetectable due to errors, or when byte synchronization is lost, the storage system can still synchronize to the data sector using the secondary sync mark. The secondary sync mark is preferably spaced apart from the primary sync mark with either a gap (no data) or user data inserted inbetween. In the latter embodiment, two methods are employed to recover user data inbetween the primary and secondary sync marks when the primary sync mark is undetectable: on-the-fly erasure pointer error correction, and buffering to facilitate retroactive synchronization. The secondary sync mark may optionally include a secondary preamble to facilitate phase locking to the data when the primary preamble is corrupted by errors. The present invention also provides 'split segment' resynchronization for synchronizing a first section of data using a first mark, and retroactively synchronizing a second section of data using a following sync mark when synchronization is lost.