Abstract: Optical wireless links automatically align themselves using feedback information that is transmitted over the light beams being aligned. Each link performs an acquisition routine in which its light beam is swept through a pre-defined pattern while transmitting its beam alignment information. When a link receives beam alignment information from a remote link, it updates its transmission to include the alignment information received from the remote link. At some point during the acquisition routine, the remote link will receive its own alignment information “echoed back” from the first link and will re-align its beam accordingly. At some point, each links will have received its own alignment information echoed back from the other link and will have aligned itself to that position. Data communication can begin at that point, or a more refined alignment step can then be performed. The alignment information can be based upon position, sample number, or time transmitted.

Abstract: A phase modulated servo method and apparatus provide acceptable position linearity for servo positioning with a narrow transducer head in a disk file. The disk file includes at least one disk mounted for rotation about an axis and the disk has at least one disk surface for storing data and has at least one transducer mounted for movement across the disk surface for writing to and for reading data and servo patterns from the disk surface. The transducer includes a read element and a write element. The read element has a width less than the write element and the read element width is greater than ⅓ of a data cylinder and less than ½ of a data cylinder. A servo pattern is written on the data disk surface having a track pitch of less than ½ of a data cylinder and the servo pattern repeats in a selected binary number of data cylinders.

Abstract: A method is disclosed for calibrating a position error signal (PES) to overcome the problem of an amplitude signal that varies as a non-linear function of real displacement when the read transducer is positioned to either side of a null position where the PES equals zero. The amplitude signal and resulting PES is notably nonlinear while reading servo burst information with a Magneto-Resistive (MR) head which has nonlinear magnetic characteristics. The calibration according to this method may be performed at anytime without need for real displacement information from a servo track writer or any sort of special calibration track. The method involves positioning the MR head to a plurality of nominal partial track displacements on either side of the null position, measuring an open loop gain value for a particular frequency at each of the displacements, deriving the coefficients of a 3.sup.rd order polynomial "gain" curve that best fits the data, integrating the "gain" curve using the coefficients to obtain a 4.

Abstract: An apparatus and method for correcting for track misregistration when a slider or head assembly contains a separate read element and write element. The offset is determined at a first position and at a second position of the actuator arm assembly. From these offsets a constant and a multiplier are determined for determining an offset as a function of the cylinder location. Also disclosed is a method and apparatus for minimizing distance traveled to prevent misregistration when repositioning between the read element and a write element. The read element is intentionally offset from the write element at an angle so as to minimize the distance traveled across the disk.