Sony Corporation

Masumi Ogawa

Takashi Okada

Mitsuyasu Asano

Masaru Nonogaki

Hiromi Kawakami

Toshiaki Meguro

A noise reduction circuit (13) in which a difference signal (S.sub.I -S.sub.I1) between the original video signal (S.sub.I) and a delayed video signal (S.sub.I1) obtained by passing the original video signal (S.sub.I) through a delay circuit (5) is obtained, and a signal obtained by passing the above difference signal (S.sub.I -S.sub.I1) through a gain control amplifier (8) is subtracted from the above original video signal (S.sub.I), and the gain which reflects movement in the gain control amplifier (8) is controlled by a movement detection signal (S.sub.M) of the above original video signal (S.sub.z) and a detection signal (S.sub.c) which reflects the input electric field strength so as not to decrease the gain of the gain control amplifier (8) at middle to weak electric field, the noise reduction circuit may be applied to a television receiver, etc.

Apparatus and method for reducing noise in a video signal

Noise reduction circuit

A discriminator for a plurality of sound intermediate frequencies which are different from each other includes a plurality of selectively operable resonance circuits each of which is formed of a winding of a respective fixed inductance value and a capacitor of a fixed capacitance value, and any deviation of the tuned frequency of a selected resonance circuit is corrected by a variable reactance element which is common to all of the resonance circuits, to thereby remove the necessity of individual adjustments, simplify the circuit configuration, and decrease the cost thereof.

Sound intermediate frequency discriminator

An intercarrier sound detecting apparatus for a television receiver includes an antenna for receiving a television signal; a tuner for selecting a desired frequency range of the received television signal from the antenna and producing a tuned signal having a video intermediate frequency component in response thereto; a filter for extracting the video intermediate frequency component from the tuned signal; video intermediate frequency amplifiers for producing a video intermediate frequency signal having an amplitude-modulated video carrier component, in response to the extracted video intermediate frequency component; a phase-locked loop which phase-locks the video intermediate frequency signal with respect to the amplitude-modulated video carrier component thereof and produces an output signal having a 4.5 MHz beat signal component in response thereto; a band pass filter for transmitting substantially only the 4.5 MHz beat signal component; and a frequency discriminator for producing a sound signal in response to the 4.5 MHz beat signal component transmitted through the band pass filter.

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Kanagawa, Japan

Masumi Ogawa