Method and apparatus for controlling media linear speed in a helical scan recorder by reading servo information just after writing the servo information

摘要

In a helical scan system for recording information on a storage media in a series of helical tracks, servo information written on the tracks is used to control linear velocity of the media during a write operation. Helical scan system includes a rotating drum upon which write heads and read heads circumferentially are mounted. The write heads and the read heads are positioned on the drum so that during a drum revolution a read head reads servo information recorded on a track at least 1.5 track pitches upstream from the most recently recorded track. A servo controller analyzes, during the recording operation, servo information read back by the read head subsequent to recording thereof by write head. Servo controller uses the servo information read by the read head to generate a signal for application to a motor for controlling linear velocity of the media during the write operation.