International Business Machines Corporation

Brian Harry Marcus

Jonathan James Ashley

Constantin Michael Melas

Glen Alan Jaquette

Mario Blaum

Dharmendra S Modha

Evangelos Stavros Eleftheriou

Roy Daron Cideciyan

Bruce Alexander Wilson

Paul Joseph Seger

Arvind M Patel

Richard M H New

Jorge Campello De Souza

Paul H Siegel

Radley Wahl Olson

Provided is a method, system, and program for providing synchronization in a binary data stream. A binary data stream is received. A synchronization mark having at least one isolated peak is generated into at least one point in the data stream. An encoded data stream is formed by concatenating the synchronization mark with the received binary data. During decoding, the synchronization mark is detected based on error propagation occurring adjacent to the at least one isolated peak of the synchronization mark.

Method, system, and program for synchronization and resynchronization of a data stream

Provided is a method, system, and program for storing input groups of uncoded binary data on a storage medium. A plurality of uncoded data blocks in a data stream are received. An encoded data stream is obtained from concatenating successive encoded blocks such that the encoded data stream includes a predetermined bit pattern comprising a plurality of bits. The bit pattern always occurs within a first number of bits and two occurrences of a '1' or '0' occur within a second number of bits. The encoded data blocks are stored on the storage medium.

Method and apparatus for encoding data to guarantee isolated transitions in a magnetic recording system

A method for write-precompensating a waveform for magnetically recording a waveform on a magnetic medium is disclosed. A user data stream is encoded into an encoded data stream so that the encoded data stream has no tribits and no consecutive dibits. No delay is applied to a first transition of a dibit of the encoded data stream. An isolated transition of the encoded data stream is delayed by a first predetermined amount of time. The second transition of a dibit of the encoded data stream is delayed by a second predetermined amount of time, such that the second predetermined amount of time is substantially twice the first predetermined amount of time. Preferably, the encoded data stream satisfies a predetermined run length limited (RLL) k&minus; constraint of k&equals;13 and a predetermined twins t-constraint of t&equals;15. In one embodiment, the encoded data stream is encoded by a block code at rate 8:10. In another embodiment, the encoded data stream is encoded by a block code at rate 16:19.

Precompensation technique and MTR code for high data rate recording

This invention is a Viterbi algorithm combined with the use of error filters outputs to produce bit reliabilities. The present invention is a SOVA-like method using error filters to reduce the complexity of bit reliability determination further than that of the ordinary SOVA method. Error patterns corresponding to each of a handful of dominant i.e., most common error patterns are determined from experimental data. Error filters determine likelihoods of each postulated error pattern. These likelihoods are then combined to produce bit reliabilities that may be passed on to an outer error correction decoder. The filters, typically six or seven of them, resolve most of the errors thereby simplifying computation dramatically.

Soft output viterbi algorithm (SOVA) with error filters

A method for designing a computer program for finding a low-complexity coder for constrained block codes for application to timing recovery or error control in data recording systems. The method includes (1) decomposing an input set of candidate codewords into simple subsets of codewords, (2) providing, for each simple subset of codewords, a respective subset of datawords, and (3) filling in certain coordinates in the datawords by values of certain coordinates in the codewords.

System and method for constructing low complexity block coders

The present invention is an encoder and decoder that eliminate all infinitely propagating error sequences for many sets of taps. The encoder includes an input circuit operable to receive an unencoded data signal and an encoding circuit, coupled to the input circuit, operable to generate the encoded data signal using a code that eliminates infinitely propagating error sequences when the encoded data signal is recovered by a decision feedback equalizer data recovery channel. The decoder includes an input circuit operable to receive an encoded data signal and a decoding table, coupled to the input circuit, operable to generate the decoded data signal using a code that eliminates infinitely propagating error sequences when the encoded data signal is recovered by a decision feedback equalizer data recovery channel.

Error propagation limiting encoder/decoder for multilevel decision

The present invention is an apparatus and method for detecting a codeword from a data stream comprising a series of sequences of samples representing intensities of an analog signal. The data stream may be output from, for example, a holographic storage device. The data stream is encoded using a code which may be represented by a trellis. One embodiment of the present invention uses a block encoded balanced code, one embodiment uses a finite state encoded balanced code and another embodiment uses a finite-state encoded DC free code. Each code defines a set of codewords which meet the constraints of the code. The codewords are detected from a sequence of samples by selecting the codeword having the greatest correlation with the sequence of samples. In a preferred embodiment, the correlation detection is implemented using the Viterbi process to iteratively determine correlations and codewords for each state at each level of the trellis based on the correlations at the preceding level of the trellis.

Encoding and detection of balanced codes

Disclosed are robust Resync patterns for insertion into a run length limited (d,k) encoded channel bit stream, which Resync pattern may be recovered from the RLL (d,k) encoded bit stream without being confused with data. The Resync pattern includes at least one string of consecutive '0's which exceeds the RLL (k) constraint, and is inserted into the channel bit stream RLL data codewords. The RLL code excludes certain patterns representing a bit shift from the Resync pattern of one or both '1' bits adjacent to the string of '0' bits, shifted to shorten the Resync pattern to within the (k) constraint. Additionally, the Resync pattern may have two different aspects, one of which is the string of '0's violating the constraints of the RLL code, and another which is specifically excluded from the RLL code, such as an excluded concatenated sequence of a VFO bit pattern of predetermined length or greater.

Run length limited encoding/decoding with robust resync

A hard disk drive read circuit for d=1 run length limited (RLL) encoded data which processes multiple consecutive data samples in parallel. The circuit of the present invention receives an analog signal from the read head of the hard disk drive. The circuit comprises a plurality of digital detection channels, coupled to the analog signal, each channel outputting an alternate bit of digital data represented by the analog signal. A timing circuit, coupled to the plurality of digital detection channels, generates a plurality of timing signals controlling the plurality of digital detection channels. The timing circuit derives timing information from one of the digital detection channels. The d=1 RLL code is modified so that there are at most nine consecutive 0's in the digital data output by the digital detection channel from which the timing circuit derives the timing information. An encoder generates the encoded digital data to be recorded on the hard disk drive.

Hard disk drive read channel with half speed timing

A one-dimensional data stream is encoded into a two-dimensional data array with reduced high frequency components, for recording on a two-dimensional recording device, such as a holographic storage device. A two-dimensional data array read from the two-dimensional recording device is decoded into the original one-dimensional data stream. To encode, a one-dimensional data stream is partitioned into a plurality of chunks of data. Each chunk of data is partitioned into a plurality of groups of bits. Each group of bits is encoded into a two dimensional data array according to a predefined constraint. A plurality of two-dimensional data arrays are concatenated into a data strip. A plurality of data strips are then assembled into a complete two-dimensional data block. To decode, a two-dimensional data stream is partitioned into multiple small two-dimensional arrays. Each array is decoded into a multi-bit group. In one embodiment, this decoding is a function of other nearby groups. Multi-bit groups are assembled to form a long chunk. Long chunks are assembled to form a one-dimensional data stream.

Two-dimensional low-pass filtering code apparatus and method

A rate 8/9, constrained partial response class IV code having run length limitation parameters (0,3/5) is provided for any partial response (PR) signaling system employing maximum likelihood (ML) detection.

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Los Altos, CA, United States of America

Brian Harry Marcus