摘要:
Methods and apparatus for interleaving data in a multitrack tape drive and for writing data on a multitrack tape in the tape drive. One method includes: partitioning the data into m(2n+k) data blocks, where each data block has a logical array of rows and columns of data bytes; error-correction coding a row and a column of the logical array to produce an encoded block; assigning the coded row to a respective location in a logical interleave array having L rows and 2n+k columns of locations; and writing a sequence of assigned coded rows simultaneously in respective data tracks on the multitrack tape. The coded row is assigned such that the minimum Euclidean distance on the multitrack tape between the coded rows is maximized. The apparatus includes units for performing the methods and the computer program product includes a program code means for causing a computer to perform the methods.
摘要:
Methods and apparatus for interleaving data in a multitrack tape drive and for writing data on a multitrack tape in the tape drive. One method includes: partitioning the data into m(2n+k) data blocks, where each data block has a logical array of rows and columns of data bytes; error-correction coding a row and a column of the logical array to produce an encoded block; assigning the coded row to a respective location in a logical interleave array having L rows and 2n+k columns of locations; and writing a sequence of assigned coded rows simultaneously in respective data tracks on the multitrack tape. The coded row is assigned such that the minimum Euclidean distance on the multitrack tape between the coded rows is maximized. The apparatus includes units for performing the methods and the computer program product includes a program code means for causing a computer to perform the methods.
摘要:
Methods and apparatus for detecting L-bit sync words occurring at N-bit intervals in PPM-encoded servo pattern read signals read in magnetic tape drives. A soft output detector processes the PPM-encoded servo pattern read signal to produce a series of soft output samples corresponding to respective bits encoded in the servo pattern. A sync word detector then produces block correlation values for respective positions of a sliding L-sample block in the series of soft output samples by (i) calculating at each block position bit correlation values indicating correlation between respective samples and corresponding bits of the sync word and (ii) summing each bit correlation value minus a predetermined function of the corresponding sample value. The sync word detector then detects a sync word at the block position with the maximum block correlation value in an (N+L−1)-sample sequence of the series of soft output samples.
摘要:
Provided are techniques for synchronous servo channel for a data tape drive. A servo reader is configured to read servo bursts from a data tape. An anti-aliasing filter is operable to output a bandlimited signal and is coupled to receive a servo channel signal comprising servo bursts from the servo reader. An analog-to-digital converter (ADC) is operable to output signal samples and is coupled to receive the bandlimited signal from the anti-aliasing filter. An interpolation and control unit is operable to output interpolated signal samples and control signals, has a first input coupled to receive the signal samples from the ADC, and has a second input coupled to receive the correlation signal samples from the dibit correlator. A dibit correlator is operable to output correlation signal samples and is coupled to receive the interpolated signal samples and control signals from the interpolation and control unit.
摘要:
A sequential data storage medium, comprising a sequence of plurality of servo patterns that provide lateral position information and longitudinal position information, wherein each of the plurality of servo patterns comprises a first burst comprising a first plurality of pulses, a second burst comprising a second plurality of pulses, a third burst comprising a third plurality of pulses, and a fourth burst comprising a fourth plurality of pulses. The spacings between the first plurality of pulses, in combination with the spacings between the second plurality of pulses, encode a first bit without affecting the recovery of lateral position information. The spacings between the third plurality of pulses, in combination with the spacings between the fourth plurality of pulses, encode a second bit without affecting the recovery of lateral position information. The sequence of plurality of servo patterns comprises a sequence of the first bits and a sequence of the second bits to form an error-correction codeword providing error-correction capability.
摘要:
Provided are techniques for synchronous servo channel for a data tape drive. A servo reader is configured to read servo bursts from a data tape. An anti-aliasing filter is operable to output a bandlimited signal and is coupled to receive a servo channel signal comprising servo bursts from the servo reader. An analog-to-digital converter (ADC) is operable to output signal samples and is coupled to receive the bandlimited signal from the anti-aliasing filter. An interpolation and control unit is operable to output interpolated signal samples and control signals, has a first input coupled to receive the signal samples from the ADC, and has a second input coupled to receive the correlation signal samples from the dibit correlator. A dibit correlator is operable to output correlation signal samples and is coupled to receive the interpolated signal samples and control signals from the interpolation and control unit.
摘要:
Methods and apparatus for detecting L-bit sync words occurring at N-bit intervals in PPM-encoded servo pattern read signals read in magnetic tape drives. A soft output detector processes the PPM-encoded servo pattern read signal to produce a series of soft output samples corresponding to respective bits encoded in the servo pattern. A sync word detector then produces block correlation values for respective positions of a sliding L-sample block in the series of soft output samples by (i) calculating at each block position bit correlation values indicating correlation between respective samples and corresponding bits of the sync word and (ii) summing each bit correlation value minus a predetermined function of the corresponding sample value. The sync word detector then detects a sync word at the block position with the maximum block correlation value in an (N+L−1)-sample sequence of the series of soft output samples.
摘要:
A method and apparatus are provided for implementing soft-input soft-output iterative detectors/decoders. Soft-input information is added directly to incoming channel samples. Input signals comprising the received incoming channel samples with the added soft-input information are detected using a detector trellis. Branch metric terms are transformed to shift all time varying terms with the added soft-input information and some constant terms after an add compare select (ACS) unit. The shifted time varying terms with the added soft-input information and the shifted constant terms are added directly to state metric terms. The soft-input information is added directly to incoming channel samples and the computation of branch metrics is not affected. This allows optimization of a dual-max detector and soft-input soft-output Viterbi detector architectures to minimize hardware complexity and power consumption.
摘要:
Methods and apparatus are provided for implementing high-speed and area efficient architectures for Viterbi detection of generalized partial response signals using both partial matched filter and matched filter metrics. In the method of the invention, branch metric terms are transformed to shift all time varying terms and some constant terms after an add compare select (ACS) unit. The total number of non-zero constants on trellis branches is minimized. The shifted time varying terms and the shifted constant terms are added directly to state metric terms. The time varying terms are expressed as outputs Zn of a partial matched filter or as outputs Wn of a matched filter. For a given generalized partial response target, the time-invariance property of the Viterbi detector enables identifying the minimum number of non-zero constants on trellis branches without resorting to heuristics. The time-invariance property holds for Viterbi detectors that process multiple samples per trellis-branch, thus allowing implementations at any desired speed.
摘要:
A method and apparatus are provided for word synchronization with large coding distance and fault tolerance for a partial-response maximum-likelihood (PRML) data channel in a direct access storage device (DASD). A Viterbi detector receives equalized PR4 samples including a predefined word synchronization pattern. The Viterbi detector is a dedicated detector optimized for detecting the predefined word synchronization pattern. The Viterbi detector includes a two-state Viterbi trellis and a word synchronization detector for the two-state Viterbi trellis. The predefined word synchronization pattern includes only even length magnets. The predefined word synchronization pattern is a repetition code including pairs of ones and pairs of zeros and includes multiple pattern match sequences. The Viterbi detector is optimized with branches removed from the Viterbi trellis, thus increasing coding distance. The two-state Viterbi trellis and word synchronization detector of the Viterbi detector operate on a 2T basis, where 1/T is the sample rate.