| 摘要 |
An information storage medium in which information is stored as multiple machine readable data entries (26) arranged in frames (24) which are themselves arranged in plural, generally parallel channels (20). The medium further contains machine readable synchronization markers (30) respectively positioned at the leading ends of the channels. These markers (30) include one or more features of characteristic shape or dimension (e.g. 76, 78, 84) or characteristically located (e.g. 81, 82, 81a, 82a) on the medium with respect to the associated channels. Preferably the medium further contains a second set of similar markers (32) arranged in respective groups alongside the respective channels. Also disclosed are method and apparatus for synchronising a read head utilizing the storage medium. Further described is a method of observing a succession of machine readable position markers in a medium comprising observing the markers in turn and observed values indicating marker position for a predetermined number of markers preceding each marker being observed, determining whether each observer value is outside a selected trend established by the stored values by more than a predetermined margin, and, if so, reducing the effect of that value. |
