US PATENT SUBCLASS 714 / 786
.~ Forward error correction by tree code (e.g., convolutional)

Current as of: June, 1999
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714 /   HD   ERROR DETECTION/CORRECTION AND FAULT DETECTION/RECOVERY

746  DF  DIGITAL DATA ERROR CORRECTION {5}
786.~ Forward error correction by tree code (e.g., convolutional) {9}
787  DF  .~.~> Random and burst errors
788  DF  .~.~> Burst error
789  DF  .~.~> Synchronization
790  DF  .~.~> Puncturing
791  DF  .~.~> Sequential decoder (e.g., Fano or stack algorithm) {1}
793  DF  .~.~> Syndrome decodable (e.g., self orthogonal)
794  DF  .~.~> Maximum likelihood
795  DF  .~.~> Viterbi decoding
796  DF  .~.~> Branch metric calculation

DEFINITION

Classification: 714/786

Forward error correction by tree code (e.g., convolutional):

(under subclass 746) Subject matter in which information bits are encoded to generate a plurality of check bits, each check bit is generated as a function of a different plurality of information bits and is interspersed among the information bits at predetermined intervals with no natural beginning point or ending point (i.e., there is no length restriction for the encoded data).

(1) Note. Convolutional coding means adding to the information a repeating sequence that is known to the receiver. By subtracting this repeating sequence and performing other tests, the receiver can determine what should have been received with a high degree of accuracy.

(2) Note. This subclass includes forward error correction, per se, (i.e., the receiver corrects the error without requiring any further information from the sender, which requires a minimum amount of redundancy in the transmission since not only must an error be detected, but its location must be determined) and forward error correction with the assistance of symbol reliability information.

(3) Note. This subclass does not include demodulation decisions based upon oversampling or on intersymbol interference alone.

(4) Note. This subclass does not include channel equalization or predistortion control based on correction results (e.g., decision feedback equalization).

(5) Note. This subclass does not include detection or

correction of errors produced by trial values, perturbations, predictions, quantizations, estimations or approximations, which errors are used as feedback for control of signal generation or coding (e.g., PID controlling, source calibration, successive approximation A/D conversion, DSV constrained encoding, predictive encoding).

(6) Note. Forward error correction (FEC) is an error-correcting technique that avoids the need for any reverse channel by enabling self-correction of errors at the receiver by adding information (at the expense of throughput) to enable the receiver to determine what the error was and the correct information to substitute for said error. SEE OR SEARCH THIS CLASS, SUBCLASS:

746, and 797, for various types of data correction such as trial values, perturbations, predictions, quantizations, estimations or approximations, which errors are used as feedback for control of signal generation or coding.

752+, for block codes wherein the information bits and associated bits form independent and distinct blocks of data bits.

799+, for various error/fault detection techniques such as those based on oversampling or intersymbol interference.

SEE OR SEARCH CLASS

341, Coded Data Generation or Conversion,

50+, for digital data conversion and subclasses 126+ for analog to or from digital conversion.

375, Pulse or Digital Communications,229+, for pulse or digital equalizers.