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:
Feb. 22, 1994
Filed:
Feb. 27, 1992
Takamitsu Kitayama, Nara, JP;
Masao Miyazaki, Nara, JP;
Tomozo Ohta, Nara, JP;
Takahiro Chihara, Nara, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
An AFC circuit stabilizes the frequency of an intermediate frequency signal to be applied to a demodulation circuit. A frequency conversion circuit responds to a local oscillation signal generated from a voltage-controlled oscillation circuit to convert the frequency of a digital modulation signal and applies the converted frequency to the demodulation circuit. A carrier reproduction circuit in the demodulation circuit reproduces the carrier of the intermediate frequency signal to output a synchronizing detection signal. The frequency of the reproduced carrier is frequency-divided by a frequency dividing circuit. A frequency division output thereof is counted by a counter for a definite period. Data is outputted from a microprocessor in response to a count output of the counter and the synchronizing detection signal, and the data is then converted into an AFC voltage by a D/A converter. The converted voltage is supplied as a control voltage to the voltage-controlled oscillation circuit. A stable intermediate frequency signal can be obtained by frequency-dividing the frequency of the carrier and counting the frequency division output thereof.