Abstract: Pulses generated from servo stripes of a servo tape system are narrowed by using non-linear gain enabling precise position of the read head. Non-linear gain based on the amplitude of each pulse is applied to each pulse to reduce jitter and distortion so as to more accurately position the read head. A non-linear gain device comprising multipliers apply a non-linear gain to a normal servo pulse signal prior, in one embodiment, to the signal being applied to a qualifier. The non-linear gain device further comprises a limiter so as to limit the gain beyond a certain threshold to 1.0. The limitation of the gain to 1.0 renders the actual amplitude of the pulse unchanged while narrowing the pulse and flattening the baseline. The resulting pulse possesses less jitter and less distortion qualities rendering the positioning of the read head more precise.

Abstract: Pulses generated from servo stripes of a servo tape system are narrowed by using non-linear gain enabling precise position of the read head. Non-linear gain based on the amplitude of each pulse is applied to each pulse to reduce jitter and distortion so as to more accurately position the read head. A non-linear gain device comprising multipliers apply a non-linear gain to a normal servo pulse signal prior, in one embodiment, to the signal being applied to a qualifier. The non-linear gain device further comprises a limiter so as to limit the gain beyond a certain threshold to 1.0. The limitation of the gain to 1.0 renders the actual amplitude of the pulse unchanged while narrowing the pulse and flattening the baseline. The resulting pulse possesses less jitter and less distortion qualities rendering the positioning of the read head more precise.

Abstract: Servo tracks combine low frequency transitions for fine transverse positioning with high frequency fields providing additional information. In one embodiment, each servo frame has a first field of recorded low frequency transitions, a second field of recorded low frequency transitions, and at least one high frequency field. The first low frequency field transitions are recorded on the tape such that a peak of each first field transitions varies in longitudinal position across the width of the servo frame. The second field of low frequency transitions are recorded on the tape such that a peak of each second field transition is not parallel with the peak of any first field transition. High frequency fields may provide one or more of timing information, longitudinal position information and gross transverse position information.

Abstract: Servo tracks combine low frequency transitions for fine transverse positioning with high frequency fields providing additional information. In one embodiment, each servo frame has a first field of recorded low frequency transitions, a second field of recorded low frequency transitions, and at least one high frequency field. The first low frequency field transitions are recorded on the tape such that a peak of each first field transitions varies in longitudinal position across the width of the servo frame. The second field of low frequency transitions are recorded on the tape such that a peak of each second field transition is not parallel with the peak of any first field transition. High frequency fields may provide one or more of timing information, longitudinal position information and gross transverse position information.

Abstract: A servo track writer head writes servo tracks on a data storage tape with increased accuracy. The servo track writer head includes a leading writer for each servo track. Each leading writer writes a synchronization field on the tape. The servo track writer head also includes a sequence of trailing writers for each servo track. Each trailing writer produces at least one trailing field on the tape a fixed distance behind the synchronization field. The servo track writer head also includes one timing writer. Each timing writer writes a timing field on the tape at a timing distance in the tape direction from each of the synchronization fields. The servo track writer head also includes a sequence of timing readers corresponding to each timing writer. The number of timing readers in the sequence is equal to the number of trailing writers in the sequence of trailing writers.

Abstract: A digital computer is provided having a clock generation circuit for generating a clock signal in response to an input signal from a fixed-frequency oscillator, which includes a first fixed-frequency oscillator and a second fixed-frequency oscillator, each providing an output signal. Also included is failure detection circuit for detecting a failure of either of the fixed-frequency oscillators, wherein a failure occurs when the first fixed-frequency oscillator or the second fixed-frequency oscillator ceases generating an output. A circuit synchronizing the output from the oscillators is coupled to both the first fixed-frequency oscillator and to the second fixed-frequency oscillator. This synchronizing circuit modifies the output from the second fixed-frequency oscillator to produce a synchronized output that is substantially synchronous with the output from the first fixed frequency oscillator.

Abstract: A digital system generates a single-phase master clock and distributes it to multiple cards and chips incorporating the functional logic of the system. A circuit in each chip divides the single clock into four spaced clock phases at the same frequency as the master clock. The individual phases are then distributed to functional logic circuits within the same chip. The circuit generates the phases by detecting the midpoints of a triangular wave produced from the single-phase master clock.

Abstract: A linear image sensor and the video channel associated with the sensor are calibrated to maximize the video signal available. The sensor is limited in output by saturation of the CCD analog shift registers in the sensor. The channel is limited by the range of the analog-to-digital converter in the channel. The useable video signal is maximized by calibrating the sensor relative to its saturation condition and by adjusting the gain of the video channel relative to the range of the analog-to-digital converter. The sensor is calibrated by adjusting its exposure to illumination. The adjustment may be made by adjusting the illumination source or by changing the sampling interval for the sensor. The gain is adjusted by using a variable gain amplifier. A microprocessor monitors the digitized video signal and controls the exposure and gain to calibrate the sensor and channel.