Overscan helical scan head for non-tracking tape subsystems reading at up to 1x speed and methods for simulation of same

Abstract

A helical scan drum design for use in non-tracking tape devices which assures 70% coverage of a track to be read by overscanning with at least two read heads at approximate 1× speed. The present invention further provides a simulation method for evaluating potential drum designs for such overscan applications. The preferred drum design uses pairs of like-azimuth read heads positioned on the rotating drum such that in combination they overlap the scan of a track by 130% the track width. These dimensions assure at least 70% coverage of each track by at least one of the pair of heads at up to 1× speed while assuring no overlap with another like-azimuth recorded track. The simulation method allows for evaluation of potential drum designs by accepting parameters describing the intended drum application and then simulating track read operations over a plurality of simulated tracks to determine the efficacy of the design over a range of tape speeds and gap widths. Designs that simulate successful reading of a sufficient threshold number of tracks over a sufficiently broad range of tape speeds may then be selected for further test and evaluation.