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:
Jan. 06, 1976
Filed:
Apr. 24, 1974
Matsushita Electric Industrial Co., Ltd., Osaka, JA;
Abstract
In a four-channel stereophonic reproducing system of the type in which a first, second, third and fourth audio signals are reproduced from two stereophonic composite signals which are respectively comprised of a left side signal consisting of a main channel signal composed of the sum of the first and second audio signals and a sub-channel signal obtained by frequency modulating or phase modulating the difference between the first and second audio signals, and a right side signal consisting of a main channel signal composed of the sum of the third and fourth audio signals and a sub-channel signal obtained by frequency modulating or phase modulating the difference between the third and fourth audio signals, a detector circuit for detecting each sub-channel signal is followed by a filter circuit for eliminating undesired higher frequencies whereby to eliminate higher audio frequencies including increased noise components to improve the S/N ratio, and at the same time a phase correction circuit is provided in the reproducing section for each main channel signal to correct for any phase distortion due to the filter circuit whereby to ensure a greatly improved separation.