摘要:
An integrated circuit controls the low level, electromechanical functionality of a computer mass storage device, such as a magnetic disk drive incorporating a spindle motor for rotatably controlling a disk and an actuator for positioning at least one read/write head with respect to the disk, to read or write encoded data configured in information data sectors and to sense encoded data of servo data sectors. A servo subsystem is coupled to an output of the read/write head for detecting the servo data sectors and providing a control signal in response thereto. An analog-to-digital subsystem is also coupled to an output of the read/write head and is operative in response to the servo subsystem control signal for converting the encoded data of the servo data sectors to digital transducer position information representative of a position of the read/write head with respect to the data tracks. A data processing subsystem is coupled to the analog-to-digital subsystem for processing the digital transducer position information and providing digital motion control signals in response thereto. A digital-to-analog subsystem is coupled to the data processing subsystem for providing analog control signals to the spindle motor and the actuator in response to the digital motion control signals.
摘要:
A burst magnitude comparator and an instruction sequencer are employed in a servo system controller to rapidly determine position correction information for moving a transducer head over the center line of a track recorded on a disk in a mass storage disk drive. The burst magnitude comparator selects at least two burst signals derived from bursts recorded at predetermined locations relative to the center line from which to derive a correction control signal, based on a predetermined relationship of the burst signals, and supplies the selected burst signals in a predetermined order to facilitate calculation of the correction signal by a data processor used with the servo system controller. An instruction sequencer controls a sequence of converting the analog burst signals from the head to digital burst signals without intervention or control from the data processor. By ordering the signals with the burst magnitude comparator and by sequencing the conversion of the signals, the calculation is speeded and the processing and code requirements for the data processor are greatly reduced, thereby reducing transport delay and freeing the resources of the processor for use in other, potentially more important tasks associated with the servo controller.
摘要:
A servo system controller for a disk drive device which includes a rotating mass storage disk incorporates a timing error determining circuit for determining rotational speed variations in the disk from information contained in a servo field recorded in a track. A timing error signal is supplied when the speed variation exceeds a threshold, thus indicating an unacceptable level of speed variation. A digital synchronizer responds to asynchronous servo data signals from the disk to establish a cell clock signal occurring about a normal frequency, a cell during which only one servo data signal will occur, and a cell data signal which occurs during the cell. The cell clock signal clocks logical operations on a synchronous basis, and servo data signals are reliably captured. A concurrence determining circuit determines the degree of concurrence between the predetermined series of cell data signals and an actual pattern of signals derived from the servo field, and recognizes the servo control information from less than complete concurrence of the derived pattern and the actual expected pattern. Normal operation is permitted even through slight inconsistences may be detected, improving data throughput while still achieving an adequate level of error tolerance.
摘要:
In an optical disk storage device, a differential phase detector is disclosed for generating a position error signal independent of the frequency content of the recorded data. A pair if diagonal signals S1 and S2 are generated by adding a pair of respective quadrants of a four-quadrant photodetector, where the phase offset between the diagonal signals represents the position error of the pit image as it passes over the photodetector. The position error is determined in the present invention by computing the difference between a positive and negative correlation of the diagonal signals S1 and S2, otherwise referred to as a dual arm correlation (DAC) ##EQU1## where .DELTA. is the correlation offset and L is the correlation length. In the preferred embodiment, the correlation offset .DELTA. is adaptively adjusted to maximize the correlation between S1 and S2. In this manner, the position error estimate is substantially insensitive to the frequency content of the recorded data. Furthermore, this method extends the position error over a range of plus or minus one-half a track, which facilitates generating a quadrature signal for use in counting track crossings during seek operations.
摘要:
The present invention provides a method for efficient use of the transmit power of a Traffic Alert Collision Avoidance System (TCAS) that allows enhanced surveillance range and limits radio frequency (RF) interference in crowded airspace. The method reduces power density in crowded airspace by modifying Mode S, Mode A and Mode C interrogations. During Mode S broadcasts, tracking interrogation power is reduced as a function of range. Further transmit power reduction is achieved by broadcasting a variable power density whisper-shout interrogation technique for Mode A/C aircraft when garbling is detected. If garbling is observed during a medium whisper-shout interrogation sequence, the method of the present invention attempts to clear the garbling by using focused high-density whisper-shout steps but only in the ranges where garbling was detected. Formation members can account for other formation members that are TCAS equipped using a special E-TCAS Broadcast Interrogation. The presence of other E-TCAS will be used in the RF interference limiting calculations. Aircraft flying in formation further minimize broadcast power by sharing information between the formation leader and formation aircraft.
摘要:
A synchronous read channel is disclosed which samples an analog read signal from a magnetic read head positioned over a magnetic disk medium, filters the sample values according to a desired partial response, extracts timing information from the filtered sample values, and detects an estimated data sequence from the filtered sample values using a trellis type sequence detector matched to the partial response. The trellis sequence detector comprises programmable detector levels which allows for maximum flexibility in matching the sequence detector to the partial response.
摘要:
A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery. Various embodiments, including an embodiment incorporating the analog functions as well as the primary digital functions of the read channel in a single integrated circuit, and preferred embodiments utilizing a reduced complexity, programmable modified Viterbi detector supporting a broad class of partial response channels are disclosed.
摘要:
Systems and methods for automatically disabling the TCAS Broadcast when aircraft join up in formation. A Traffic Collision Avoidance System (TCAS) determines if the aircraft is approaching formation flight with other aircraft or flying in formation with other aircraft and disables a TCAS interrogation signal if the aircraft is determined to be approaching a formation or flying in formation. The TCAS receives TCAS interrogation signals from one or more other aircraft and receives aircraft configuration information from one or more other aircraft systems. The TCAS determines the aircraft is approaching formation flight or flying in formation based on the received TCAS interrogation signals, a mode of TCAS operation, and/or the received aircraft configuration information. The TCAS also automatically switches into Traffic Advisory Only mode if the aircraft is determined to be approaching formation flight or flying in formation.
摘要:
Systems and methods for automatically disabling the TCAS Broadcast when aircraft join up in formation. A Traffic Collision Avoidance System (TCAS) determines if the aircraft is approaching formation flight with other aircraft or flying in formation with other aircraft and disables a TCAS interrogation signal if the aircraft is determined to be approaching a formation or flying in formation. The TCAS receives TCAS interrogation signals from one or more other aircraft and receives aircraft configuration information from one or more other aircraft systems. The TCAS determines the aircraft is approaching formation flight or flying in formation based on the received TCAS interrogation signals, a mode of TCAS operation, and/or the received aircraft configuration information. The TCAS also automatically switches into Traffic Advisory Only mode if the aircraft is determined to be approaching formation flight or flying in formation.
摘要:
A method for reworking a ceramic structure. A number of holes are formed in a portion of the ceramic structure in which a rework of the ceramic structure is desired. The ceramic structure has a plurality of layers in the portion in which the rework is desired. A ceramic bonding material is introduced into the number of holes formed in the portion of the ceramic structure. The ceramic bonding material is cured in the portion of the ceramic structure.