Abstract: A magnetic disk drive data storage disk defines recording tracks divided into data sectors by narrow servo spokes. A data sector lying between servo spokes is recorded with user data encoded in accordance with a code having a predetermined distance and user data code rate. Each servo spoke of the recording area has at least one servo information field encoded in a wide bi-phase code pattern. The disk drive further includes a synchronous sampling data detection channel having a data transducer head positioned by a servo-controlled actuator over the recording track, a preamplifier for receiving electrical analog signals magnetically induced by the data transducer head from flux transitions present in at least the servo information field, a digital sampler for synchronously sampling the electrical analog signals to produce digital samples, and wide bi-phase decoding circuitry coupled to receive digital samples from the synchronous sampling data detection channel for decoding the wide bi-phase code pattern.

Abstract: Embedded servo sectors within a data track of a hard disk drive including a rotating data storage disk and a closed loop rotary actuator structure for positioning a data transducer head relative to the data track are written by a method including the steps of positioning the rotary actuator structure relative to the data track with a laser-interferometer-based servo writer and writing a pattern of circumferentially sequential, radially offset fine position bursts within each servo sector with the data transducer head, this step including writing-in undetermined position errors within each pattern being written, moving the disk drive to a self scan environment away from the servo writer, operating the rotary actuator structure in closed loop for following the data track by reference to the servo burst pattern, extracting the undetermined position error from each pattern thereby to iteratively determine written-in position errors, generating burst correction values from the determined written-in position errors

Abstract: A magnetic disk drive data storage disk defines recording tracks divided into data sectors by narrow servo spokes. A data sector lying between servo spokes is recorded with user data encoded in accordance with a code having a predetermined distance and user data code rate. Each servo spoke of the recording area has at least one servo information field encoded in a wide bi-phase code pattern. The disk drive further includes a synchronous sampling data detection channel having a data transducer head positioned by a servo-controlled actuator over the recording track, a preamplifier for receiving electrical analog signals magnetically induced by the data transducer head from flux transitions present in at least the servo information field, a digital sampler for synchronously sampling the electrical analog signals to produce digital samples, and wide bi-phase decoding circuitry coupled to receive digital samples from the synchronous sampling data detection channel for decoding the wide bi-phase code pattern.

Abstract: A head suspension has an integrated multi-layer trace conductor array for supporting and electrically interconnecting a read/write head to electronic circuitry in a disk drive. The trace conductor array includes an integrally formed electrical shield which may be grounded or ungrounded and formed to have a depth greater than a skin effect depth at a frequency of an interfering wave front.

Abstract: Embedded servo sectors within a data track of a hard disk drive including a rotating data storage disk and a closed loop rotary actuator structure for positioning a data transducer head relative to the data track are written by a method including the steps of positioning the rotary actuator structure relative to the data track with a laser-interferometer-based servo writer and writing a pattern of circumferentially sequential, radially offset fine position bursts within each servo sector with the data transducer head, this step including writing-in undetermined position errors within each pattern being written, moving the disk drive to a self scan environment away from the servo writer, operating the rotary actuator structure in closed loop for following the data track by reference to the servo burst pattern, extracting the undetermined position error from each pattern thereby to iteratively determine written-in position errors, generating burst correction values from the determined written-in position errors

Abstract: A method of holographic recording in a photorefractive medium wherein stored holograms may be retrieved with maximum signal-to noise ratio (SNR) is disclosed. A plurality of servo blocks containing position feedback information is recorded in the crystal and made non-erasable by heating the crystal. The servo blocks are recorded at specific increments, either angular or frequency, depending whether wavelength or angular multiplexing is applied, and each servo block is defined by one of five patterns. Data pages are then recorded at positions or wavelengths enabling each data page to be subsequently reconstructed with servo patterns which provide position feedback information. The method of recording data pages and servo blocks is consistent with conventional practices. In addition, the recording system also includes components (e.g.

Abstract: Apparatus and method for detecting occurrence of a non-pulse interval of predetermined length between a beginning pulse and an ending pulse as included within a sequence comprising a unique timing mark within a stream of pulses supplied from a source with a state machine. The method of the state machine includes the the steps of:advancing through a plurality of nominal states marking in time the non-pulse interval,branching to one of a plurality of available spurious pulse states from one of the nominal states upon detection of a first unexpected pulse,returning to advance through predetermined remaining ones of the plurality of nominal states following detection of the first unexpected pulse,reaching a completion state following the nominal states if only the first unexpected pulse is detected, andreaching an error state following a branch to another one of the plurality of available spurious pulse states upon detection of a second unexpected pulse within the non-pulse interval.

Abstract: A clock generation circuit includes a reference clock for putting out a stable reference clocking signal. A digital ring oscillator includes a series circuit loop having at least one inverting gate and a programmable delay line of plural delays formed a series of tapped digital transmission gates connected between an output and an input of the inverting gate. A multiplexer selects among the series of taps in accordance with a tap selection signal. A clock monitoring circuit is connected to compare the clock output with a stable reference clocking signal to produce a digital clock cycle count. A programmed microcontroller generates the tap selection value as a function of the digital clock cycle count and a desired clock output frequency set point.