302results about "Other error detection/correction/protection" patented technology

A system for measuring a property of a sample is provided. The system comprises a diagnostic measuring device having a memory and a diagnostic test strip for collecting the sample. The strip has embedded thereon a pattern representative of at least first data and second data, the first data being data representing at least one of parameters related to measuring the property, codes usable for calibration of the diagnostic measuring device, or parameters indicating proper connection between the measuring device and the test strip and the second data usable for detecting and rejecting potential errors affecting the proper measurement of the property.

A method and a circuit system for checking an m out of n code are provided. The method uses a code checker, to which at least one code reducer is assigned, a reduction of the code word width to in each case half being carried out using the at least one code reducer until a 1 out of x (x=n / 2, n / 4, n / 8 . . . ) code or another code which is not reducible further in this way is provided, each step of the code reducer additionally being connected to different bits of a counter, the 1 out of x code or the code which is not further reducible being checked and additionally the signal pairs of each step being checked.

A disk drive is disclosed comprising a head actuated over a disk. A redundancy generator generates a plurality of redundancy symbols appended to user data to form a codeword C(x) written to a selected data sector on the disk. During a read operation, a syndrome generator generates a plurality of error syndromes in response to a received codeword C′(x) generated by reading the selected data sector. An error detector, responsive to the error syndromes, detects a number of errors in the received codeword C′(x), and a plurality of counters count a number of times the number of errors falls within a predetermined plurality of ranges to thereby provide a distribution of the errors. The error distribution is used, for example, for selecting a track density or ECC depth, or for failure prediction or defect mapping.

Error correction is tailored for the use of an ECC for correcting asymmetric errors with low magnitude in a data device, with minimal modifications to the conventional data device architecture. The technique permits error correction and data recovery to be performed with reduced-size error correcting code alphabets. For particular cases, the technique can reduce the problem of constructing codes for correcting limited magnitude asymmetric errors to the problem of constructing codes for symmetric errors over small alphabets. Also described are speed up techniques for reaching target data levels more quickly, using more aggressive memory programming operations.

Methods and apparatus are provided for measuring the performance of a read channel. A number of detection techniques, such as SOVA and maximum-a-posteriori (MAP) detectors, produce a bit decision and a corresponding reliability value associated with the bit decision. The reliability value associated with the bit decision may be expressed, for example, in the form of log likelihood ratios (LLRs). The reliability value can be monitored and used as a performance measure. The present invention provides a channel performance measure that generally correlates directly to the BER but can be collected in less time.

A method for processing a chain reaction codes includes first selecting a source symbol which is associated an output symbol of degree two or higher (i.e., an output symbol which is itself associated with two or more input symbols), and subsequently deactivating the selected source symbol in an attempt to produce an output symbol of degree one. The inactivation process can be repeated either successively until an output symbol of degree one is identified, and / or whenever the decoding process is unable to locate an output symbol of degree one.

A channel has a first and a second end. The first end of the channel is coupled to a transmitter. The channel is capable of transmitting symbols selected from a symbol set from the first end to the second end. The channel exhibits incomplete error introduction properties. A code comprises a set of code words. The elements of the set of code words are one or more code symbols long. The code symbols are members of the symbol set. The minimum modified Hamming separation between the elements of the set of code words in light of the error introduction properties of the channel is greater than the minimum Hamming distance between the elements of the set of code words. A memory device, a method of using the channel, and a method of generating the code are also described.

Efficient methods for encoding and decoding Half-Weight codes are disclosed and similar high density codes are disclosed. The efficient methods require at most 3·(k−1)+h / 2+1 XORs of symbols to calculate h Half-Weight symbols from k source symbols, where h is of the order of log(k).

A method for decoding a codeword in a data stream encoded according to a low density parity check (LDPC) code having an m×j parity check matrix H by initializing variable nodes with soft values based on symbols in the codeword, wherein a graph representation of H includes m check nodes and j variable nodes, and wherein a check node m provides a row value estimate to a variable node j and a variable node j provides a column value estimate to a check node m if H(m,j) contains a 1, computing row value estimates for each check node, wherein amplitudes of only a subset of column value estimates provided to the check node are computed, computing soft values for each variable node based on the computed row value estimates, determining whether the codeword is decoded based on the soft values, and terminating decoding when the codeword is decoded.

An encoder encodes digital signals representative of data by classifying the digital signals into first and second classes indicative of their influence on data quality and subjects them to error detection encoding capable of generating at least two error detection codes which respectively correspond to the first and second classes. A decoder receives the encoded digital signals classified into first and second digital signal classes, decodes the error detection codes, and generates error signals, corresponding to the respective digital signal classes, from which the quality of the received digital signals is estimated and the utility of the received digital signals is determined.

Efficient methods for encoding and decoding Half-Weight codes are disclosed and similar high density codes are disclosed. The efficient methods require at most 3·(k−1)+h / 2+1 XORs of symbols to calculate h Half-Weight symbols from k source symbols, where h is of the order of log(k).

Block modulus coding (BMC) systems implement block coding on non-binary modulus m symbols, where m is greater than 2. BMC systems can be used for, among other things, forward error correction (FEC) of source data in communication systems or parity backup for error correction of source data in storage systems where the source data is represented by non-binary symbols that may be corrupted by burst errors. The block coding is preferably performed using a distributed arrangement of block encoders or decoders. A distributed block modulus encoder (DBME) encodes sequential source data symbols of modulus m with a plurality of sequential block encoders to produce interleaved parity codewords. The codewords utilize modulus m symbols where the medium can reliably resolve m symbol states. The interleaved parity codewords enable decoding of error-corrected source data symbols of modulus m with a distributed block modulus decoder (DBMD) that utilizes a plurality of sequential block decoders to produce the error-corrected source data symbols.

Method and apparatus for providing data recovery in a one or multiple disk loss situation in a RAID5 like system. A data storage apparatus has a plurality of n disks storing data comprising a plurality of n data groupings stored across the plurality of n disks. Each one of the n data groupings comprises a data portion and a redundancy portion. The size of the data portion relative to the redundancy portion is as H to Q, where H / Q<(n-m) / m, where m is the maximum number of disks that may be lost at any given time. Advantageously, the n data portions are recoverable from any and all combinations of n-m data grouping(s) on n-m disk(s) when the other m data grouping(s) are unavailable, where 1<=m<n.

A communications system and protocol for use in a non-dominant bit radio network. The radio network includes transceivers which communicate with other transceivers to allow network variables to be shared by all transceivers. The protocol allows the network to handle collisions between competing transmissions from different transceivers. The protocol also handles communications between transceivers that are out of transmitting range of each other.

A channel has a first and a second end. The first end of the channel is coupled to a transmitter. The channel is capable of transmitting symbols selected from a symbol set from the first end to the second end. The channel exhibits incomplete error introduction properties. A code comprises a set of code words. The elements of the set of code words are one or more code symbols long. The code symbols are members of the symbol set. The minimum modified Hamming separation between the elements of the set of code words in light of the error introduction properties of the channel is greater than the minimum Hamming distance between the elements of the set of code words. A memory device, a method of using the channel, and a method of generating the code are also described.

In an encoder for encoding symbols of data using a computing device having memory constraints, a method of performing a transformation comprising loading a source block into memory of the computing device, performing an intermediate transformation of less than all of the source block, then replacing a part of the source block with intermediate results in the memory and then completing the transformation such that output symbols stored in the memory form a set of encoded symbols. A decoder can perform decoding steps in an order that allows for use of substantially the same memory for storing the received data and the decoded source block, performing as in-place transformations. Using an in-place transformation, a large portion of memory set aside for received data can be overwritten as that received data is transformed into decoded source data without requiring a similar sized large portion of memory for the decoded source data.

An apparatus and method for transmitting / receiving a signal in a communication system are provided. A signal reception apparatus of a communication system receives a signal and generates a child Low Density Parity Check (LDPC) codeword vector by decoding the received signal according to a child parity check matrix supporting a first coding rate. The child LDPC codeword vector includes an information vector including A (A≧1) information bits, and when the first coding rate is equal to a coding rate for a case where D (D≧1) parity bits are punctured among B (B≧1)+C (C≧1) parity bits included in a parent LDPC codeword vector generated by encoding the information vector according to a parent parity check matrix supporting a second coding rate, a child bipartite graph corresponding to the child parity check matrix is generated such that a parent bipartite graph corresponding to the parent parity check matrix corresponds to an edge merge scheme.

Aspects of a system for physical layer aggregation may include one or more switch ICs and / or physical (PHY) layer ICs that enable reception of data packets via a medium access control (MAC) layer protocol entity. Each of the received data packets may be fragmented into a plurality of fragment payloads. Each of the plurality of fragment payloads may be sent to a PHY layer protocol entity instance a physical layer protocol entity instance selected from a plurality of physical layer protocol entity instances.

A method evaluates an error-correcting code for a data block of a finite size. An error-correcting code is defined by a parity check matrix, wherein columns represent variable bits and rows represent parity bits. The parity check matrix is represented as a bipartite graph. A single node in the bipartite graph is iteratively renormalized until the number of nodes in the bipartite graph is less than a predetermine threshold. During the iterative renormalization, a particular variable node is selected as a target node, and a distance between the target node and every other node in the bipartite graph is measured. Then, if there is at least one leaf variable node, renormalize the leaf variable node farthest from the target node, otherwise, renormalize a leaf check node farthest from the target node, and otherwise renormalize a variable node farthest from the target node and having fewest directly connected check nodes. By evaluating many error-correcting codes according to the method, an optimal code according to selected criteria can be obtained.

Free-space optical (FSO) laser communication systems offer exceptionally wide-bandwidth, secure connections between platforms that cannot other wise be connected via physical means such as optical fiber or cable. However, FSO links are subject to strong channel fading due to atmospheric turbulence and beam pointing errors, limiting practical performance and reliability. We have developed a fade-tolerant architecture based on forward error correcting codes (FECs) combined with delayed, redundant, sub-channels. This redundancy is made feasible though dense wavelength division multiplexing (WDM) and / or high-order M-ary modulation. Experiments and simulations show that error-free communications is feasible even when faced with fades that are tens of milliseconds long. We describe plans for practical implementation of a complete system operating at 2.5 Gbps.

Methods and apparatus are provided for measuring the performance of a read channel. A number of detection techniques, such as SOVA and maximum-a-posteriori (MAP) detectors, produce a bit decision and a corresponding reliability value associated with the bit decision. The reliability value associated with the bit decision may be expressed, for example, in the form of log likelihood ratios (LLRs). The reliability value can be monitored and used as a performance measure. The present invention provides a channel performance measure that generally correlates directly to the BER but can be collected in less time.

A retransmission control method comprising: generating N parity check matrices; generating a generator matrix containing a check symbol generator matrix contained in the first parity check matrix; transmitting the codeword generated by using the generator matrix to another communications device; generating, when the communications device receives a NAK in response to the codeword, a first additional parity by using the second parity check matrix; and retransmitting the first additional parity to the another communications device.

Efficient methods for encoding and decoding Half-Weight codes are disclosed and similar high density codes are disclosed. The efficient methods require at most 3·(k−1)+h / 2+1 XORs of symbols to calculate h Half-Weight symbols from k source symbols, where h is of the order of log(k).

A magnetic recording disk drive has head positioning servo sectors with servo sector numbers (SSNs) that are not recorded on the disk. The SSNs are encoded through the use of multiple servo sector types that are arranged in a specific sequence around the data tracks. The different servo sector types are identified by unique types of servo timing marks (STMs), which are used to locate the servo sectors. The SSNs that are used to identify the servo sectors on the track form a set or code of m fixed n-bit patterns. A SSN is determined when the STM types read from n sequential servo sectors match one of the fixed SSN pattems. A set or code of m servo sectors, where each servo sector is identified by a unique SSN pattern having length n, is denoted as an (m,n,d) code, where d is referred to as the minimum Hamming distance of the code. The Hamming distance between two patterns refers to the number of locations that are different between the two pattems.

A method and apparatus for communicating data is provided. The data is encoded in accordance with a run length limited (RLL) code. A seed is appended to the RLL encoded data. The seed can be used to alter the error correction code (ECC) parity to meet an RLL constraint.

In an encoder for encoding symbols of data using a computing device having memory constraints, a method of performing a transformation comprising loading a source block into memory of the computing device, performing an intermediate transformation of less than all of the source block, then replacing a part of the source block with intermediate results in the memory and then completing the transformation such that output symbols stored in the memory form a set of encoded symbols. A decoder can perform decoding steps in an order that allows for use of substantially the same memory for storing the received data and the decoded source block, performing as in-place transformations. Using an in-place transformation, a large portion of memory set aside for received data can be overwritten as that received data is transformed into decoded source data without requiring a similar sized large portion of memory for the decoded source data.

A retransmission control method comprising: generating N parity check matrices; generating a generator matrix containing a check symbol generator matrix contained in the first parity check matrix; transmitting the codeword generated by using the generator matrix to another communications device; generating, when the communications device receives a NAK in response to the codeword, a first additional parity by using the second parity check matrix; and retransmitting the first additional parity to the another communications device.

Methods and apparatus are provided for computing soft data or log likelihood ratios for received values in communication or storage systems. Soft data values or log likelihood ratios are computed for received values in a communication system or a memory device by obtaining at least one received value; identifying a segment of a function corresponding to the received value, wherein the function is defined over a plurality of segments, wherein each of the segments has an associated set of parameters; and calculating the soft data value or log likelihood ratio using the set of parameters associated with the identified segment. The computed soft data values or log likelihood ratios are optionally provided to a decoder.