Abstract: The invention is a servo compensation method and system for use in a disk storage system. The disk storage system experiences error that causes a head to become mis-aligned with the disk. The error comprises multiple spin-frequency harmonic run-out error and other servo position errors. During follow mode, a digital filter processes a position error signal to generate a compensation signal. The position error signal is comprised of components representative of the multiple spin-frequency harmonic run-out error and the other servo position errors. The compensation signal is comprised of components that cause the servo positioning system to compensate for the multiple spin-frequency harmonic run-out error and the other servo position errors. The digital filter also operates as an oscillator that provides an oscillating signal at multiples of the spin frequency of the disk during seek mode.

Abstract: An invention for more accurately initiating the generation of detection windows for detecting data within a stream of data pulses is disclosed. A high frequency clock, typically operating at rate corresponding to a multiple of the nominal clock rate (e.g., two or three times, is used for a portion of a decoder system. In one embodiment, a down counter and a detection window generation component of the decoder system are clocked at the higher rate, while the remaining elements are clocked at the nominal clock rate. In this manner, the detection windows are more accurately initiated, while the remaining portions of the decoder system do not require the extra expense imposed of operating at the higher clock rate. Using the present invention, synchronization delay is minimized and detection windows are more accurately aligned with data pulses which reduces the error rate and improves performance of the decoder system.

Abstract: A disk drive processing system controls a Servo Timing Mark (STM) detection window in disk drive during a head switch operation. In response to the head switch operation, the system disables a timer that closes the STM detection window during normal operation, and the system tracks the elapsed time from a time point. The system compares the elapsed time to a programmable limit value. The system resumes normal operation if an STM is detected before the elapsed time reaches the programmable limit value and initiates a recovery procedure if the elapsed time reaches the programmable limit value. Advantageously, the programmable limit value can be easily re-programmed if a larger STM detection window is required due to severe STM or head mis-alignment.

Abstract: An invention for intelligently adjusting the timing of generation of a series of detection windows to maintain synchronization with the occurrence of data pulses within a stream of phase-encoded binary data is disclosed. In an embodiment of the present invention, thresholding logic is added to a limited response self-clocking decode phased locked loop to achieve a more robust data detection method and system, which is less susceptible and sensitive to noise error. In one embodiment of the system, an up/down counter is used to count to occurrence of late and early data pulses within their respective detection window, with the timing of the generated series of detection windows being adjusted when the value of this counter exceeds an upper or lower predetermined threshold value.

Abstract: A method and apparatus for performing head switch operations in a magnetic disk system having a magnetic disk device that is segmented into a plurality of cylinders, which cylinders are grouped into an inner zone, a middle zone, and an outer zone. The inner zone is near the innermost area of the magnetic disk device. The outer zone is near the outermost area of the magnetic disk device. The middle zone is in between the inner zone and the outer zone. The head switch is performed from a current head to a target head. Prior to the head switch, the system determines if the current cylinder is in either the inner zone or the outer zone. When the current cylinder is in either the inner zone or the outer zone, the system seeks the current head to the middle zone, whereupon the system performs a head switch from the current head to the target head. When the current cylinder is not found to be in either the inner zone or the outer zone, i.e.

Abstract: A method and apparatus for performing head switch operations in a magnetic disk system with a magnetic disk device that is segmented into a plurality of cylinders. The cylinders are grouped into an inner zone, a middle zone, and an outer zone. The inner zone is near the innermost area of the magnetic disk device. The outer zone is near the outermost area of the magnetic disk device. The middle zone is in between the inner zone and the outer zone. The head switch is performed from a current head at a current cylinder to a target head at a target cylinder. Prior to the head switch, the system determines if the current cylinder is in either the inner zone or the outer zone. If the current cylinder is in either the inner zone or the outer zone, then the system determines if the target cylinder is in either the inner zone or the outer zone. If the target cylinder is in either the inner zone or the outer zone, then the system seeks the current head to the middle zone and then performs the head switch.

Abstract: The invention is a servo compensation method and system for use in a disk storage system. The disk storage system experiences error that causes a head to become mis-aligned with the disk. The error comprises run-out error and other servo position errors. During follow mode, a digital filter processes a position error signal to generate a compensation signal. The position error signal is comprised of components representative of the run-out error and the other servo position errors. The compensation signal is comprised of components that cause the servo positioning system to compensate for the run-out error and the other servo position errors. The digital filter also operates as an oscillator that provides an oscillating signal the spin frequency of the disk during seek mode.