Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Motohiko Takeuchi

Masaaki Kisou

Seiichi Yanagida

Hideki Marumoto

A noise reduction circuit stores the video signal of one frame as input through an A/D converter from a VTR main body, into a frame memory via a first subtracting circuit. A second subtracting circuit subtracts the delayed video signal delayed one frame, which is derived from said frame memory, from the video signal. The same outputs the subtraction result as a difference signal. The amplitude level of the video signal is detected by the detecting circuit. The nonlinear characteristic appropriate to the difference signal output from the subtracting circuit is selected by the level signal output from the detecting circuit. Subtracting circuit subtracts the noise component selected and extracted by the nonlinear processing circuit from the video signal, thereby to remove the noise component. The video signal with no noise component is applied through a D/A converter from the subtracting circuit, to a CRT display where it is visualized.

Noise reduction circuit for video signal having suitable nonlinear

A noise reduction circuit allows a field memory to store 1-field data of a video signal through a subtracting circuit. The video signal is supplied from a VTR through an A/D converter. The noise reduction circuit causes a subtracting circuit to subtract a delayed video signal, which is supplied from the field memory with a 1-field time delay, from the video signal and allows the resultant signal to be output as a field difference signal. A noise component included in the video signal is extracted by a noise extracting circuit in accordance with the field difference signal, and is output to the subtracting circuit. In a comparing circuit, the noise component is compared with a predetermined reference value so as to determine whether the video signal represents a motion or motionless picture. In accordance with this determination result, memory control circuit controls whether to write the video signal supplied from the subtracting circuit in the field memory. In addition, a video signal from which the noise component is removed is supplied from the subtracting circuit and monitored on a CRT display through a D/A converter or the like.

Noise reduction circuit for video signal having field memory

In a method and device for controlling the tracking in a playback mode in accordance with at least four pilot signals of different frequencies f1, f2, f3 and f4 which are sequentially recorded together with information signals on tracks of a recording medium in a predetermined cyclic sequence and which satisfy a relationship .vertline.f1-f2.vertline.:.vertline.f2-f3.vertline.:.vertline.f3-f4.vertli ne.=A:B:A, an extraction section extracts pilot signal components from reproduced signals obtained by playing back the recording medium. A reference signal supplying section supplies four reference signals which have the same relationship those of the four pilot signal frequencies f1, f2, f3 and f4 and a different cyclic sequence from that of the four pilot signals. A comparing and detecting section compares the extracted pilot signal components with the corresponding reference signals and detects differences between the two pilot signal components extracted from the right and left tracks adjacent to the reproduced track and the corresponding reference signals so as to obtain two difference frequency signal components which respectively have predetermined constant frequencies in any track. A detecting and generating section detects a level difference between the two difference frequency signal components and generates a tracking control signal having a polarity and level which correspond to a tracking error.

Method and device for controlling the tracking

A magnetic recording system which comprises a recording/reproducing head for effecting recording and reproduction of data with respect to one recording track formed on a magnetic tape, an erasing head disposed in side by side relation with respect to the head and secured thereto, for effecting erasing with respect to two tracks, i.e., the track traced by the recording/reproducing head and the next track, an auto-tracking circuit for compensating for the deviation of the position of the recording/reproducing head with respect to the start track for rerecording, and a switch control section for controlling the operation of the erasing head by causing switching of a switch circuit connected to the erasing head.

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Yokohama, Japan

Motohiko Takeuchi