Abstract: A method, and a system for implementing such method, for use in a magnetic disk storage system for compensating for variation in spin speed of a data storage media from a nominal or design spin speed. The method includes providing the nominal spin speed for the data storage media in the particular magnetic disk storage system and then measuring the actual spin speed of the data storage media. In one preferred embodiment, the spin speed measurement is completed by measuring the time from one servo position field to the next sequential servo position field in a track on the data storage media. Next, the present spin speed variation is determined by comparing the measured spin speed with the nominal spin speed. A correction factor is calculated based on the spin speed error and applied to at least one data transfer parameter, such as channel reference frequency or read/write gate assertion timing, prior to a subsequent data transfer process (i.e., a read or a write operation).

Abstract: A variable delay circuit, known as a delayed read data single shot (DRDSS) circuit, adapted for use in a data read channel which reads signals recorded with different clock frequencies in different zones on a data storage device, wherein the read channel includes a variable oscillator whose reactive impedance is supplied with a charging current whose level corresponds to the clock frequency of the zone being read. A current duplicator produces an output current that is a substantially identical duplicate of the charging current to provide an output level as a function of that output current, this output level being compared to a ramp signal, whereby a delayed version of the signal read from the data storage device is produced when the ramp signal is substantially equal to the output level.

Abstract: A variable delay circuit, known as a delayed read data single shot (DRDSS) circuit, adapted for use in a data read channel which reads signals recorded with different clock frequencies in different zones on a data storage device, wherein the read channel includes a variable oscillator whose reactive impedance is supplied with a charging current whose level corresponds to the clock frequency of the zone being read. A current duplicator produces an output current that is a substantially identical duplicate of the charging current to provide an output level as a function of that output current, this output level being compared to a ramp signal, whereby a delayed version of the signal read from the data storage device is produced when the ramp signal is substantially equal to the output level.