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. 25, 1986
Filed:
Nov. 09, 1983
Yoichi Sakamoto, Takatsuki, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A synchronous receiver having a reduced pull-in time without requiring a frequency error detection circuit using a differentiator is provided with a voltage-controlled oscillator, a 90.degree. phase shifter which shifts the phase of an output from the voltage controlled oscillator by an angle of 90.degree., first and second synchronous detectors which detect an in-phase component and a quadrature component of a video carrier signal, a phase detector for detecting a phase difference between the video carrier signal and the output of the voltage-controlled oscillator, a first low pass filter for filtering the output of the phase detector, a frequency discriminator for discriminating the frequency of an audio IF signal generated by the first synchronous detector and a second low pass filter for filtering the output of the frequency discriminator. The output of the first and second low pass filters are fed back to the voltage-controlled oscillator so that the phase difference between the output of the first and second synchronous detectors is made equal to 0.