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. 16, 1993
Filed:
Mar. 01, 1991
Michael D Sidman, Colorado Springs, CO (US);
Digital Equipment Corporation, Maynard, MA (US);
Abstract
An automatic gain control circuit for controlling amplification of two independent input signals in which first and second attenuators are connected to receive the input signals and each attenuator is selectively switchable to vary its output between maximum and minimum attenuations such that the sum of the outputs of the attenuators are held at a substantially constant reference level. The circuit is used in a disk drive with a data surface comprising circular data tracks divided into sectors each of which includes a data field and a servo field containing embedded servo signals, an embedded signal sensor for sensing embedded servo signals on a data surface and a head positioning system for positioning a read/write head over a selected data track. The servo fields in the data tracks contain first and second embedded servo signals of substantially equal amplitude offset relative to each other and disposed on alternate sides of the track centerlines. The sensed signals corresponding to the first and second embedded servo signals are sampled, amplified using the automatic gain control circuitry and compared to provide a track error signal for positioning the read/write head over a selected data track.