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:
Aug. 29, 1989
Filed:
Aug. 17, 1988
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A frequency demodulator includes an analog-to-digital converter for converting an inputted FM signal into a digital signal. A 90.degree. phase shifter is used to phase shift the converted digital signal. The phase shifted signal and the converted signal are utilized to determine the results of tan.sup.-1 (X/Y). X represents the converted signal, and Y represents the phase shifted signal. The result from the calculation is delayed for a period of time equal to one sampling cycle. The frequency demodulator also includes a subtractor for subtracting the delayed signal from the calculation result. A discontinuity corrector corrects any discontinuity in an output from the subtractor, and a reversal phenomenon compensator compensates the output from the discontinuity corrector when the output from the discontinuity corrector exceeds a predetermined range of levels. These levels correspond to an appearance of discrete lines of black or white color on a reproduced picture.