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:
Jun. 22, 1976
Filed:
Jan. 28, 1975
Hirotaka Kurata, Tokyo, JA;
Sansui Electric Co., Ltd., Tokyo, JA;
Abstract
Improvements in a stereo signal demodulator of a receiver in a four-channel stereo system, in which system upon transmitting four sound source signals (LF, LB, RF and RB) from one station, the transmission is carried out for a synthesized signal composed of a signal in a main channel of (LF + LB) + (RF + RB), a pilot signal, a signal in a first sub-channel consisting of a double side-band signal obtained by modulating an m-multiple frequency-multiplied signal of the pilot signal with a signal of (LF + LB) - (RF + RB), a signal in a second sub-channel consisting of a double side-band signal obtained by modulating the same, m-multiple frequency-multiplied but phase-shifted signal with a signal of (LF - LB) + (RF - RB), and a signal in a third sub-channel consisting of a single side-band signal (SSB or VSB) obtained by modulating an n-multiple (m < n) frequency-multiplied signal of the pilot signal with a signal of (LF - LB) - (RF - RB). The four-channel stereo signal demodulator comprises a circuit for deriving from the pilot signal in said synthesized signal that has been FM-detected by a tuner an m-multiple frequency-multiplied signal of said pilot signal, a signal obtained by phase-shifting said m-multiple frequency-multiplied signal, and an n-multiple frequency-multiplied signal of said pilot signal; first, second and third switching circuits for switching their input signals consisting of said synthesized signal, respectively, under control of the respective three outputs of said signal deriving circuit to demodulate the signals in said respective channels from said synthesized signal; and a matrix circuit having the outputs of said three switching circuits applied to its input for separating and emitting at its output the signals LF, LB, RF and RB. The improvements reside in that a filter and a phase-compensator circuit are electrically coupled in the input circuit for the synthesized signal to said third switching circuit, and in that the outputs of said first and second switching circuits are applied to the input of the matrix circuit through the intermediary of respective delay lines.