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:
Oct. 17, 1989
Filed:
Dec. 06, 1988
Yoshihisa Sakazaki, Yokohama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
In a digital FM demodulating apparatus of this invention, an input video signal is converted into a predetermined digital FM signal, e.g., Asin.theta. by a recording signal processor and supplied from an input terminal to a phase shift circuit. The phase shift circuit divides digital FM signal Asin.theta. into digital FM signals Asin.theta..sub.2 and Acos.theta..sub.2 phase-shifted from each other through 90.degree. and outputs the signals directly to an operational circuit. The digital FM signal Asin.theta. is converted into digital FM signals A'sin.theta..sub.1 and A'cos.theta..sub.1 delayed from signals Asin.theta..sub.2 and Acos.theta..sub.2 by predetermined periods by registers and supplied to the operational circuit. The operational circuit calculates signals Asin.theta..sub.2, Acos.theta..sub.2, A'sin.theta..sub.1 and A'cos.theta..sub.1. A result of tan.sup.-1 conversion of an output from the calculator performed by a ROM having a tan.sup.-1 conversion table is obtained as a value obtained by differentiating a phase component of signal Asin.theta. by a time from an output terminal.