Track deviation measuring method and track deviation measuring apparatus

Abstract

Track deviation of a recorded track on a magnetic tape is measured in a non-destructive manner according to a measuring method and an apparatus employing the same. A magnetic tape recorded with an FM signal on its tracks conforming to a standard system, is loaded to the apparatus conforming to the same standard, and having a rotary drum with a head, thereby the tape is transported in a longitudinal direction and scanned helically by the head, the apparatus comprises device for setting measuring points along the tracks, device for stepwise shifting the tape causing head positions to displace stepwise along a track traversing line passing the measuring points perpendicularly to the tracks, device for measuring levels of the FM signal at displaced positions of the head device for converting thus measured levels into digital data, device for estimating, by using the digital data, a specific head position at which a maximum level of the FM signal is reproduced within each of the track traversing line, each specific head position having a positional value and device for subtracting a predetermined positional value from each positional value of the specific rotary head positions located along the tracks, wherein the predetermined positional value is determined to be a track center of standard track having a slant angle conforming to the standard, so that values of the track deviation varying along a track are measured.