Matsushita Electric Industrial Co., Ltd.

Syuichi Ninomiya

Sukeichi Miki

Masashi Kanno

Tsuneo Takezaki

This invention provides an FM four channel stereo signal generator for generating from four stereophonically related audio signals an FM four channel stereo signal expressed by (S.sub.1 +S.sub.2 +S.sub.3 +S.sub.4) + (S.sub.1 +S.sub.2 -S.sub.3 -S.sub.4)sin.omega.t+(S.sub.1 -S.sub.2 -S.sub.3 +S.sub.4)cos.omega.t+pilot signals with or without (S.sub.1 -S.sub.2 +S.sub.3 -S.sub.4)sin2.omega.t. The generator includes a matrixing device for producing from the four audio signals four matrixed audio signals (aS.sub.1 +bS.sub.2 +bS.sub.3 +cS.sub.4), (bS.sub.1 +aS.sub.2 +CS.sub.3 +bS.sub.4), (bS.sub.1 +cS.sub.2 +aS.sub.3 +bS.sub.4) and (cS.sub.1 +bS.sub.2 bS.sub.3 +aS.sub.4), where 2b=a+c; a main gating circuit for producing from the audio or the matrixed audio signals a main gated signal including a four channel stereo signal and harmonics; and a subsidiary gating circuit for producing from the audio or the matrixed audio signals a subsidiary gated signal corresponding to a harmonic nearest the four channel stereo signal, whereby by combining the audio or the matrixed audio signals, the main and the subsidiary gated signals and the pilot signals, and by passing the thus combined signal through a low pass filter, the desired four channel stereo signal of high quality can be easily produced.

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Kadoma, Japan

Syuichi Ninomiya