Abstract: A track map of a disk drive is generated to compensate for various conditions. A track map is a stored measurement of every “half” servo track width on a disk. Every servo half track width is measured in the factory on a disk and then the data is stored on the disk for use during drive operations. When an individual track is accessed, the appropriate servo half track width data is pulled from memory and is used to adjust a scale factor for that local half track width. The track map may be used to compensate for various conditions including varying servo track width, microjog distance, and data track spacing.

Abstract: A track map of a disk drive is generated to compensate for various conditions. A track map is a stored measurement of every “half” servo track width on a disk. Every servo half track width is measured in the factory on a disk and then the data is stored on the disk for use during drive operations. When an individual track is accessed, the appropriate servo half track width data is pulled from memory and is used to adjust a scale factor for that local half track width. The track map may be used to compensate for various conditions including varying servo track width, microjog distance, and data track spacing.

Abstract: A track map of a disk drive is generated to compensate for various conditions. A track map is a stored measurement of every “half” servo track width on a disk. Every servo half track width is measured in the factory on a disk and then the data is stored on the disk for use during drive operations. When an individual track is accessed, the appropriate servo half track width data is pulled from memory and is used to adjust a scale factor for that local half track width. The track map may be used to compensate for various conditions including varying servo track width, microjog distance, and data track spacing.

Abstract: An automatic digital control system includes a proportional integral derivative (PID) compensator in which the digital differentiator portion, with its associated zero-order hold, is implemented according to an algorithm that reduces phase loss as a function of frequency. The digital differentiator is based only on a present error sample so that the output of the digital differentiator (with its ZOH) is made to resemble an amplitude-balanced step function (i.e., a doublet) during a given sample period T. The step transition occurs at one-half of the period (i.e., at T/2). Another embodiment further reduces phase loss by confining the output waveform of the differentiator to some fraction of the total sampling period. During the remaining portion of the sampling period the digital differentiator (again, with its associated ZOH) is forced to some desired reference level.