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:
Mar. 25, 1980
Filed:
Mar. 20, 1978
Robert Price, Lexington, MA (US);
John W Craig, Sudbury, MA (US);
Avraham Perahia, Simi Valley, CA (US);
Hartvig E Melbye, Wayland, MA (US);
Sperry Corporation, New York, NY (US);
Abstract
A digital magnetic recording system is disclosed that utilizes partial response signalling to achieve the Nyquist data pulse rate with minimum bandwidth. A. C. bias is introduced to linearize the magnetic medium which, inter alis, permits reliable multilevel (greater than 2) data storage without impairing data accessibility. Preferably Class IV partial response is utilized with one or more sinusoidal lobes in the data frequency spectrum. The basic binary data to be stored is converted to, for example, ternary and the ternary data is precoded. The precoded ternary data is recorded on the magnetic medium via an interleaved dipulse sequence having a spectral null slightly outside the data frequency band. A pilot tone is inserted at the spectral null for timing recovery and automatic gain control.