Helical Scan

The means by which a head on a videocassette recorder scans the magnetic tape. The playback head on a VCR is not aligned perfectly with the tape transport mechanism, but is rather skewed at a 30º angle. It thus is able to contact and process more of the tape surface. The video head also rotates as the tape moves past it, making one rotation per frame. The addition of a second play head allows each field to be read separately.

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