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:
Feb. 29, 2000
Filed:
Dec. 17, 1996
Mark Andrew Bergquist, Rochester, MN (US);
Jonathan Darrel Coker, Rochester, MN (US);
Richard Leo Galbraith, Rochester, MN (US);
Rick Allen Philpott, Rochester, MN (US);
David James Stanek, Rochester, MN (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
Methods and apparatus are provided for detecting servo information in a direct access storage device. A plurality of data symbols are read from a disk to produce a readback signal. Each data symbol and each sequence of data symbols contains servo identification information. A correlation filter provides a matched filter function of an expected readback signal of the plurality of data symbols to produce a correlated readback signal. A threshold detector is coupled to the correlation filter for identifying a threshold signal representative of the data symbol. A data separator responsive to the threshold detector windows the threshold signal and provides clock and data signals. The data separator includes a digital variable frequency oscillator (VFO) which optimally centers incoming servo information from the disk in a timing window and provides standard clocked data for a servo processor. The threshold detector has a variable threshold voltage that is programmed using a trim digital-to-analog converter (DAC).