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. 17, 1998
Filed:
Oct. 28, 1996
Tsuneo Fujiwara, Nara, JP;
Tomiyuki Numata, Tenri, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
A clock extracting section generates a first clock synchronized with a reproducing signal, and a second clock with a frequency twice a frequency of the first clock. An AD converter quantizes the reproducing signal at timing of the second clock. A data classifier classifies the quantized data into two quantized data streams with a period of the first clock. Each equalizer equalizes the two quantized data streams to (1,1) and (1,2,1) partial response characteristics. Each branch metric arithmetic unit calculates a corresponding branch metric respectively. A synthesizer calculates a sum of them so as to generate a synthetic branch metric. An ACS circuit and a data decoding section Viterbi-decode data according to the synthetic branch metric. As a result, even if an SN ratio is lowered by increase in interference between codes and a noises at the time of recording at high density, an error of decoded data can be decreased.