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:
Sep. 18, 1984
Filed:
Oct. 13, 1981
Hitachi, Ltd., Tokyo, JP;
Abstract
A circuit for reproducing and demodulating a modulated digital signal which is modulated in a predetermined modulation system such as MFM, EFM and so on. A phase of a clock having a frequency multiplied by an integral number of a bit frequency of the modulated digital signal, is restricted or controlled by a signal showing that a predetermined pattern of the modulated digital signal occurred. The modulated digital signal is demodulated by the thus restricted clock to produce digital informations '0' and '1'. A main requirement for detecting the predetermined pattern of the modulated digital signal, is that a reproduced modulated digital signal is reliable. In order to compensate for the drop-out of the modulated digital signal, the demodulation circuit is provided with a modulated digital signal reproducing circuit for complementing a predetermined signal pattern when the drop-out occurred.