Abstract: A read channel network of a magnetic data storage device receives analog signals representative of user data and servo data, wherein the servo data is usable to position a read/write magnetic head. The servo data is separately processed within the read channel network to improve the signal to noise ratio of the user data signal and, thereby, permit improved positioning accuracy of the read/write head within the magnetic data storage device. The servo signal applied to a multiplier along with an oscillating signal reference signal to produce a sideband signal, which is passed through a bandpass filter having a bandwidth about that of the sideband signal and having a center frequency substantially the same as that of the sideband signal. Additionally, the signal output by the bandpass filter is processed by an envelope detector, and then by an A/D converter and digital filter to produce a digital signal representative of the servo signal.

Abstract: A read channel network of a magnetic data storage device receives analog signals representative of user data and servo data, wherein the servo data is usable to position a read/write magnetic head. The servo data is separately processed within the read channel network to improve the signal to noise ratio of the user data signal and, thereby, permit improved positioning accuracy of the read/write head within the magnetic data storage device. The servo signal applied to a multiplier along with an oscillating signal reference signal to produce a sideband signal, which is passed through a bandpass filter having a bandwidth about that of the sideband signal and having a center frequency substantially the same as that of the sideband signal. Additionally, the signal output by the bandpass filter is processed by an envelope detector, and then by an A/D converter and digital filter to produce a digital signal representative of the servo signal.

Abstract: A magnetic head and disk tester includes a magnetic head which is selectively positioned relative to a rotatably mounted magnetic disk to accomplish testing of either of the head or disk or both. The magnetic head is secured to a carriage which is under electro-mechanical control, wherein displacement of the carriage causes a corresponding displacement of the head relative to the disk and, to some degree, may cause yaw in the carriage. Measurements of the linear position of a left and a right side of the carriage are detected, measured, and fed back to a control system. The control system responds to a difference between a desired command position and the actual position of each side of the carriage and causes actuators to adjust the position of each side of the carriage until the difference, and thereby the yaw, is substantially eliminated. Additionally, during a positioning operation, vibrations in the yaw direction are decreased, which decreases a corresponding settling time of the magnetic head.

Abstract: An apparatus for balancing the spinstand of a magnetic head and disk testing system includes a base that rotationally supports a rotating spindle. The spindle supports a pack of disks and a slide moveable along guide rails of the spinstand. The slide, in turn, supports a stack of magnetic heads that is moveable in respect to the pack of disks. The spindle supports a balancing cap that has a plurality of threaded openings uniformly spaced in its peripheral surface. Imbalance is adjusted by threading screws into or out of the selected threaded openings. The value of imbalance is defined by vibration measurements; these measurements are performed by means of an accelerometer attached to the spindle housing, and of a rotary encoder that generates index pulse in a certain position of the spindle.