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:
Dec. 29, 1987
Filed:
Jan. 16, 1985
Susumu Takahashi, Tokyo, JP;
Hiroshi Iida, Tokyo, JP;
Sansui Electric Co., Ltd., Tokyo, JP;
Abstract
This invention discloses an AM stereo transmission method characterized in that when left and right audio signals L and R are transmitted as an AM stereo signal which is represented by S=A cos(.omega.t+.phi.) wherein A denotes an amplitude, .omega. a carrier angular frequency and .phi. a phase angle given by tan.sup.-1 (L-R)/1+L+R, the audio signal of low frequency is transmitted at an amplitude A=(1+L+R), and the audio signal of high frequency is transmitted at an amplitude A=.sqroot.(1+L+R).sup.2 +(L-R).sup.2. The modulator according to the present invention comprises a matrix circuit for providing signals (L+R) and (L-R), an orthogonal modulator to produce an AM stereo signal .sqroot.(1+L+R).sup.2 +(L-R).sup.2 cos(.omega.t+.phi., an amplitude controller, an amplitude control signal generator circuit and a low-pass filter. In the modulator the said AM stereo signal S is changed to the signal (1+L+R)cos(.omega.t+.phi.) for audio signal of low frequency by controlling the amplitude controller. The demodulator according to the present invention comprises an amplitude controller to which the AM signal S=A cos(.omega.t+.phi.) is inputted, an orthogonal demodulator, an matrix circuit for driving signals L and R from signals (L+R) and (L-R) obtained by the orthogonal demodulator, an amplitude control signal generator circuit and a low-pass filter. In the demodulator the said AM stereo signal S=(1+L+R)cos(.omega.t+.phi.) for audio signal of low frequency is changed to the signal .sqroot.(1+L+R).sup.2 +(L-R).sup.2 cos(.omega.t+.phi.) by controlling the amplitude controller.