# US 2013/0154858 A1 · Methods and systems for decoding data > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154858 A1 - Document ID: US20130154858A1 - Status: Published application - Kind: A1 - Application number: 13/331,708 - Filed: 2011-12-20 - Published: 2013-06-20 - Earliest claimed: 2011-12-20 - Assignees: General Electric Company - Inventors: Budhaditya Deb; John Anderson Fergus Ross - Web page: https://patentgrep.com/patent/US20130154858A1 ## CPC - G11B 20/10287: {using probabilistic methods, e.g. maximum likelihood detectors (G11B20/10277 takes precedence)} - G11B 20/10009: {Improvement or modification of read or write signals} - G11B 20/1423: {Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code} - H03M 5/14: Code representation, e.g. transition, for a given bit cell depending on the information in one or more adjacent bit cells, e.g. delay modulation code, double density code - H04L 1/0047: {Decoding adapted to other signal detection operation (in conjunction with sequence estimation or equalization H04L25/03286)} - H04L 1/0063: {Single parity check} - H04L 25/067: {providing soft decisions, i.e. decisions together with an estimate of reliability (H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178)} - G11B 2220/2504: Holographic discs; Holographic digital data storage [HDDS] - G11B 2220/2537: Optical discs - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method of decoding is presented. The method includes the steps of receiving a coded bit stream that is generated by encoding source information using a Non Return to Zero Inverted (NRZI) code, selecting an NRZI decoding method based on one or more parameters associated with noise in the received coded bit stream, and generating a plurality of decisions by processing the received coded bit stream using the selected NRZI decoding method, wherein the received coded bit stream comprises a plurality of coded bits, and the plurality of decisions are estimates of a plurality of source bits in the source information. ## Claims ### Claim 1 A method, comprising: receiving a coded bit stream that is generated by encoding source information using a Non Return to Zero Inverted (NRZI) code; selecting an NRZI decoding method based on one or more parameters associated with noise in the received coded bit stream; and generating a plurality of decisions by processing the received coded bit stream using the selected NRZI decoding method, wherein the received coded bit stream comprises a plurality of coded bits, and the plurality of decisions are estimates of a plurality of source bits in the source information. ### Claim 2 (depends on 1) The method of claim 1, wherein processing the received coded bit stream, comprises: determining a plurality of branch metrics corresponding to a plurality of branches of trellis diagram corresponding to NRZI code; determining a plurality of probability functions based on forward recursion and backward recursion using the plurality of branch metrics; determining A-Posteriori probabilities (APP) corresponding to a plurality of nodes and the plurality of branches of the trellis diagram based on the plurality of probability functions; and generating the plurality of decisions corresponding to the plurality of coded bits based on the A-Posteriori probabilities. ### Claim 3 (depends on 1) The method of claim 1, wherein processing the received coded bit stream, comprises: determining a first likelihood function corresponding to a coded bit among the plurality of coded bits; determining a second likelihood function corresponding to the coded bit; creating a first hypothesis that a decision among the plurality of decisions corresponding to the coded bit is equal to zero using the first likelihood function and the second likelihood function; creating a second hypothesis that the decision among the plurality of decisions corresponding to the coded bit is equal to one using the first likelihood function and the second likelihood function; and comparing the first hypothesis with the second hypothesis to generate the decision among the plurality of decisions corresponding to the coded bit. ### Claim 4 (depends on 1) The method of claim 1, wherein processing the received coded bit stream, comprises: determining a value of a polynomial function based on a coded bit among the plurality of coded bits; and comparing the value of the polynomial function with a threshold value to generate a decision among the plurality of decisions corresponding to the coded bit. ### Claim 5 (depends on 1) The method of claim 1, wherein the one or more parameters comprises a type of the noise and a level of the noise in the received coded bit stream. ### Claim 6 (depends on 5) The method of claim 5, wherein the type of the noise comprises optical noise and electrical noise. ### Claim 7 (depends on 1) The method of claim 1, wherein the NRZI decoding method comprises a Bahl, Cocke, Jelinek, and Raviv (BCJR) method, a Hypothesis Test method, or an Analog XOR method. ### Claim 8 (depends on 7) The method of claim 7, wherein the BCJR method comprises: initializing a first prior probability that a source bit in the plurality of source bits is equal to zero; and initializing a second prior probability that the source bit in the plurality of source bits is equal to one. ### Claim 9 (depends on 8) The method of claim 8, wherein the BCJR method comprises initializing the first prior probability and the second prior probability equal to 0.5. ### Claim 10 (depends on 8) The decoding method of claim 8, wherein the first prior probability and the second prior probability have different values. ### Claim 11 (depends on 7) The decoding method of claim 7, wherein the Analog XOR method is based on a Gaussian Channel model or a Gaussian noise model. ### Claim 12 A system, comprising: a data storage device for storing a coded bit stream encoded using a Non Return to Zero Inverted (NRZI) code; a processing system communicatively coupled with the data storage device, wherein the processing system is configured to: select an NRZI decoding method based on one or more parameters associated with noise in the coded bit stream; and generate a plurality of decisions by processing the coded bit stream using the selected NRZI decoding method, wherein the coded bit stream comprises a plurality of coded bits, and the plurality of decisions are estimates of a plurality of source bits in a source information. ### Claim 13 (depends on 12) The system of claim 12, wherein the coded bit stream includes a run length limited (RLL) coded sequence of bits. ### Claim 14 (depends on 12) The system of claim 12, wherein the NRZI decoder employs an optimal Maximum A-posteriori Probability (MAP) decoder. ### Claim 15 (depends on 12) The system of claim 12, wherein the NRZI decoder employs a trellis based suboptimal decoder. ### Claim 16 (depends on 12) The system of claim 12, wherein the NRZI decoder is configured to process the coded bit stream using modulo 2 additions and hypothesis comparisons. ### Claim 17 (depends on 12) The system of claim 12, wherein the NRZI decoder comprises a Bahl, Jelinek, Cocke, and Raviv (BCJR) method, a Hypothesis Test method, or an Analog XOR method. ### Claim 18 (depends on 12) The system of claim 12, wherein the plurality of decisions comprise a hard decision or a soft decision. ### Claim 19 (depends on 12) The system of claim 12, wherein the data storage device comprises an optical storage device, an optical disk, or a universal serial bus (USB) device. ### Claim 20 (depends on 12) The system of claim 12, further comprising an output device for outputting the plurality of the decisions in a determined format. ### Claim 21 (depends on 20) The system of claim 20, wherein the output device comprises a display device, an audio device, a printer, or combinations thereof. ### Claim 22 (depends on 12) The system of claim 12, wherein the processing system comprises a decoder, an optical disk reader, a digital versatile disk player, or a compact disk player. ### Claim 23 A communication system comprising: an encoder generating a coded bit stream that is encoded using a Non Return to Zero Inverted (NRZI) code; a decoder that receives the coded bit stream via a communication channel, wherein the decoder is configured to: select an NRZI decoding method based on one or more parameters associated with noise in the received coded bit stream; and generate a plurality of decisions using the selected NRZI decoding method, wherein the coded bit stream comprises a plurality of coded bits, and the plurality of decisions are estimates of source bits in a source information.