A plurality of scanner bars is arranged in precisely located holes in the
frame of a media handling device to detect the passage of the lead and
trail edge of media. The multiplicity of scanner bars, arranged linearly
at a right angle to the direction of motion of the media, is sampled at
some frequency. The scanner bars give not only arrival and departure time
of the media from each scanner bar location, but also making some
assumptions about the shape of the media, information about the
orientation of the media relative to the direction of motion. This
information can be used to diagnose improper media handling mechanisms
upstream of the sensor or provide information to downstream corrective
mechanisms. Preprinted test media, such as, ladder charts, etc., can be
used to extract velocity profiles and other paper path dynamic
characteristics.