Abstract: In a tape having separate servo bands of patterns positioned laterally across the tape, the patterns of a separate servo band have at least one differentiating characteristic with respect to patterns of another of the separate servo bands. The differentiating characteristic allows identification of the separate servo bands. For example, the patterns of a separate servo band have differing azimuthal orientations of detectable transitions with respect to another servo band, such as being laterally inverted. In another, variations in the width of gaps of patterns are made with respect to another servo band. In another, variations are made in the number of the detectable transitions of patterns with respect to the patterns of another servo band.

Abstract: In a magnetic tape system, during lateral repositioning of a tape head between servo bands, the servo head is not on a servo band and is unable to provide servo position information. Hence, information about the lateral position may be lost. A control system selectively senses data read transducers of the tape head; and, upon detecting a servo signal of a servo band from a sensed data read transducer, determines the lateral position of the tape head with respect to the detected servo band based upon the position of the data read transducer that sensed the detected servo signal.

Abstract: Disclosed are a system, a method, and article of manufacture to provide for filtering a servo signal in a tape drive using a matched filter that is optimized for the operating tape velocity of the tape drive. A servo controller for track following on a tape uses a digital filter implementation of the matched filter to produce a filtered servo signal. The digital filter is optimized for different tape velocities by selecting digital filter coefficients for the digital filter that depend upon the tape velocity presently in use. The filtered servo signal is used by the servo controller to provide improved track following in a tape drive.

Abstract: In magnetic tape having separate longitudinal servo bands of servo information with superimposed data information, the separate servo bands have selected different superimposed data information, to identify the separate servo bands for independent addressability. The servo information comprises non-parallel laterally extending transitions to indicate lateral positioning, and the selected different superimposed data information may comprise a lack thereof in portion(s) of the servo bands. Where the superimposed data information is longitudinal position information of the tape, the selected different superimposed data information may comprise different longitudinal position information of one or more servo band(s). The selected different superimposed data information may comprise a band identifier in the superimposed data information of one or more of the servo bands.

Abstract: A method and position control for a servo system for positioning a head laterally with respect to defined servo tracks. The servo system comprises a servo sensor and detector for sensing lateral position of the head and a compound actuator having a fine actuator portion and a coarse actuator portion. The position control provides position indications for the coarse actuator portion, which may comprise a table relating predetermined nominal lateral position indications to the defined servo tracks. The position control positions the coarse actuator portion at an estimated position with respect to the defined servo tracks, and responds to the servo sensor to determine which servo track is closest to the estimated position. The position control sets the coarse actuator portion position indication to the predetermined nominal lateral position indication of the closest defined servo track, e.g., by looking it up in the table. This thereby corrects the indication of the position of the coarse actuator portion.

Abstract: In a tape drive system performing read/write operations on a tape by inserting a tape cartridge into a tape drive, the tape cartridge having a tape on which servo and data tracks are arranged longitudinally and a predetermined servo pattern is recorded on each of the servo tracks, a method and system for re-setting coefficients of a low-pass filter for servo control of the tape drive, each time the tape cartridge is inserted into the tape drive so that a servo system of the tape drive is stabilized. More specifically, the servo pattern is read from the tape in the cartridge inserted into the tape drive, frequency analysis for the read servo pattern is performed, a singularity that exceeds a predetermined spectrum range is detected from frequency components obtained by the frequency analysis, and the coefficients of the low-pass filter are set so as to cancel a power spectrum of the singularity.

Abstract: A method and system for detecting and counting angular rotation of a rotating rotor of a brushless DC motor. The position of the rotor is sensed with a group of sensors. The group of sensors have at least six states determined by the position of the rotor, and in each of these states, the group of sensors define an associated, respective numeric value. At defined periods, the state of the sensors is identified, and the numeric value associated with that state is used to determine the direction of rotation of the rotor and the angular movement of the rotor during the time of the period. In a preferred embodiment, the group of sensors includes at least three sensors, and each of the associated numeric values includes at least three digits. Also, in each of the at least six states, each of the at least three sensors contributes one digit to the numeric value associated with the state.

Abstract: A servo system and method position a head laterally with respect to defined servo tracks, employing fine and coarse actuators. A servo control integrates the position error between the head and a desired position in accordance with a predetermined function, and operates the coarse actuator to translate the fine actuator and the head in accordance with the integrated position error. A position error signal loop is coupled to a servo sensor for determining position error for operating the fine actuator to translate the head in a manner to reduce the position error. The position error signal loop may have a compensator function with both integration and other functions. A coarse servo control comprises a connection coupled to the compensator function for providing an integration control representing the integration function of the position error signal loop; and a driver coupled to the connection, operating the coarse actuator to translate the fine actuator and the head in accordance with the integration signal.

Abstract: A servo system and method position a head laterally with respect to magnetic tape longitudinal defined servo bands arranged in a longitudinally shifted pattern for identification, and separated by data tracks. A servo controller responds to a loss of lateral position, sensing an estimated longitudinal position of the magnetic tape. If the estimated longitudinal position is within a predetermined distance of an end of the tape, the servo controller operates a drive to continuously move the tape away from the sensed end. The servo controller senses a home lateral position sensor to determine whether a compound actuator is within a predetermined distance of the edge of the magnetic tape. If so, it operates the coarse actuator portion of the compound actuator to move laterally away from the edge of the magnetic tape; else, to move toward the edge.

Abstract: A system and method for precisely registering and synchronizing data sets on a recording media having a prerecorded servo pattern. The recording media is subject to continuing movement for reading and/or writing the data sets, interrupted by stopping at the end of a selected data set and restarting. During the continuing movement of the recording media, a detector coupled to the servo system continuously reads linear position registration data modulated into the prerecorded servo pattern. An interpolator interpolates the prerecorded registration data to provide precision registration information for the data sets. Upon the drive stopping the recording media, then back hitching the media and the movement restarting, selected read and interpolated registration information is provided.

Abstract: In a tape drive system performing read/write operations on a tape by inserting a tape cartridge into a tape drive, the tape cartridge having a tape on which servo and data tracks are arranged longitudinally and a predetermined servo pattern is recorded on each of the servo tracks, a method and system for re-setting coefficients of a low-pass filter for servo control of the tape drive, each time the tape cartridge is inserted into the tape drive so that a servo system of the tape drive is stabilized. More specifically, the servo pattern is read from the tape in the cartridge inserted into the tape drive, frequency analysis for the read servo pattern is performed, a singularity that exceeds a predetermined spectrum range is detected from frequency components obtained by the frequency analysis, and the coefficients of the low-pass filter are set so as to cancel a power spectrum of the singularity.

Abstract: Disclosed are a method and a detector for adaptively detecting servo gaps in a timing based servo pattern prerecorded on a variable velocity media. The timing based servo pattern has groups of repeated pairs of non-parallel transition stripes arranged in bursts, the bursts separated by servo gaps whose length is variable. A servo system sensor senses the transition stripes in the longitudinal direction of the media. A group interval detector coupled to the sensor detects the timing interval between the same slope transition stripes of two sequential groups of bursts. A divider divides the detected group timing interval by a predetermined divisor to provide a divided timing interval gap detection threshold. A sequential stripe interval detector coupled to the sensor measures the timing interval between stripes, and a comparator compares the divided timing interval and the timing interval, identifying a servo gap upon the measured timing interval at least equaling the gap threshold.

Abstract: A detector and method for detecting data modulated into a timing based servo pattern prerecorded on a media, comprising shifts of pairs of non-parallel transition stripes arranged in a frame of two bursts. Timing intervals between sequential transition stripes are detected. Interval comparison logic compares selected timing intervals and indicates whether the compared intervals represent a “0”, or a “1”. First and second counters respectively increment the number of the compared intervals representing a “0” and representing a “1” in each frame. Bit comparison logic compares, for each frame, the incremented numbers representing a “0” and a “1” to a predetermined criteria and, upon one of the numbers meeting the criteria, identifies the corresponding “0” or “1” as the bit value for the frame. The bits are data comprising longitudinal position words arranged in a linear sequence.

Abstract: The invention provides a system for compensating for hard sector noise degradation of tracking error signals in an optical data storage system. The system includes a hard sector detection circuit which generates a first output signal in response to receiving a first input signal representing detection of a hard sector on a magneto-optical disk; a logic circuit which generates a second output signal in response to receiving the first output signal and a second input signal; and a tracking error signal reconstruction circuit which generates an approximated tracking error signal in response to receiving a tracking error signal and the second output signal. The invention may be embodied as hardwired circuitry or as a combination of hardware and software embodied in a computer readable medium and implemented in a digital computer.

Abstract: The invention provides a system for compensating for hard sector noise degradation of tracking error signals in an optical data storage system. The system includes a hard sector detection circuit which generates a first output signal in response to receiving a first input signal representing detection of a hard sector on a magneto-optical disk; a logic circuit which generates a second output signal in response to receiving the first output signal and a second input signal; and a tracking error signal reconstruction circuit which generates an approximated tracking error signal in response to receiving a tracking error signal and the second output signal. The invention may be embodied as hardwired circuitry or as a combination of hardware and software embodied in a computer readable medium and implemented in a digital computer.