Error detection systems

Claim 2

A plural-channel digital-signal transfer system for exchanging signals with plural tracks on a record member; means scanning said tracks for exchanging signals therewith with such signal exchanges with the respective tracks having different probabilities of errors; means repeatedly arranging parallel groups of signals with respect to said tracks; the improvement including in combination: first polynomial-type error detection and correction means (ECC1 means) for receiving said groups of signals and generating check signals capable of indicating a first set of errors and correcting a second set of errors less than said first set, said signals in the respective tracks having a predetermined mathematical relationship to said ECC-1 means polynomial wherein given tracks exhibiting a given probability of error greater than other tracks are related only to nonadjacent terms of said ECC-1 means polynomial; means associating each said signal groups with each said ECC-1 means check signals in said tracks; and second error detection means (ECC-2 means) being of a polynomial type for receiving said groups of signals and generating check signals for indicating a third set of errors less than said first and second sets but including errors not in said first and second sets and having a polynomial-to-track relationship different from such relationship to said ECC-1 means.

Claim 3

The system set forth in claim 1 further including a third error detection means (ECC-3 means) receiving said groups of signals and capable of detecting errors therein and having yet another track-to-polynomial relationship and thereby checking some signal errors not checked by said ECC-2 means.

Claim 4

Error detection and correction apparatus for operating with a set of data signals consisting of sequential sub-groups of data, each sub-group haviNg error detection and correction first check bit residues having a capability of indicating a given number of bits in error; ECC-1 means for operating with said first check bit residues and having said capability of detecting said given number of bits in error; second error detection means (ECC-2 means) operating on all of said sub-groups and having a capability of error correction less than said first-mentioned error detection and correction and operating with a second check bit residue smaller than said first check bit residue; said ECC-1 means receiving said signals including said residues for comparing said first residue with the received data signals for correcting errors therein; said ECC-2 means receiving said corrected signals and said second residue for verifying proper correction in accordance with said first residue; and each ECC means being constructed in accordance with an error code including a polynomial having a plurality of terms relating to input positions of the respective ECC means; permutation means interposed between said data signals and one of said ECC means for altering the mathematical relationships between the data and the respective error detection and correction polynomials by altering signal inputs to said positions, said permutation means being adjusted in accordance with error patterns expected in the transmission of said data signals.

Claim 5

Error detection and correction apparatus for operating with a set of data signals consisting of sequential sub-groups of data, each sub-group haviNg error detection and correction first check bit residues having a capability of indicating a given number of bits in error; ECC-1 means for operating with said first check bit residues and having said capability of detecting said given number of bits in error; second error detection means (ECC-2 means) operating on all of said sub-groups and having a capability of error correction less than said first-mentioned error detection and correction and operating with a second check bit residue smaller than said first check bit residue; said ECC-1 means receiving said signals including said residues for comparing said first residue with the received data signals for correcting errors therein; said ECC-2 means receiving said corrected signals and said second residue for verifying proper correction in accordance with said first residue; and each ECC means being constructed in accordance with an error code including a polynomial having a plurality of terms relating to input positions of the respective ECC means; permutation means interposed between said data signals and one of said ECC means for altering the mathematical relationships between the data and the respective error detection and correction polynomials by altering signal inputs to said positions, said permutation means being adjusted in accordance with error patterns expected in the transmission of said data signals.

Claim 6

The apparatus set forth in claim 3 including nonlinear means in one of said permutation means for introducing a nonlinear relationship between one of said error code polynomials and said data sets while maintaining a linear relationship between said data sets and another one of said ECC means.

Claim 7

The apparatus set forth in claim 4 wherein said nonlinear means is introduced in said permutation means between said data set and said ECC-2 means, and said ECC-2 means further including a residue based upon not only the data signals, but also said first residue.

Claim 8

The apparatus set forth in claim 5 wherein said nonlinear means includes changing the coded form of the data, and said permutation means further including switching means for altering the relationship of the nonlinearly changed data to said ECC-2 means.

Claim 11

The method set forth in claim 7 further including the step of introducing a linear change in said data set with respect to said second error detection code as compared with the relationship of the data set to said first error detection code, said linear change including altering the relationship of data portions to polynomial terms mathematically representing the error detection apparatus.

Claim 12

The method set forth in claim 8 further including segmenting said data sets and employing said first error correction respectively on each of said segments, such application being independently applied to each of said segments; employing a third error detection code similar to said second error detection code on said entire set of data for detecting errors and miscorrections made by employing said first error correction code; and employing said second error detection code to check not only the data sets, but all of the residual redundancies of said first and third error correction code operations.

Claim 13

Apparatus for encoding data having a plurality of check bit redundancies, including in combination; first error correction code means operating on received data sets and supplying an error correction indicating residue; nonlinear encoding means receiving said data sets and said residue for effecting a nonlinear code change in both sAid data set and said residue; and second error detection means receiving said nonlinearly encoded data and residue, and generating second check bit residue based upon said received nonlinearly coded data and residue and supplying said nonlinearly encoded signals and said second error detection code residue as output coded values.

Claim 14

Apparatus for encoding data having a plurality of check bit redundancies, including in combination; first error correction code means operating on received data sets and supplying an error correction indicating residue; nonlinear encoding means receiving said data sets and said residue for effecting a nonlinear code change in both sAid data set and said residue; and second error detection means receiving said nonlinearly encoded data and residue, and generating second check bit residue based upon said received nonlinearly coded data and residue and supplying said nonlinearly encoded signals and said second error detection code residue as output coded values.

Claim 15

A decoding system for receiving input nonlinearly coded values including data and first check bit residues, the improvement including in combination: a nonlinear decoder converting said received input coded values into nonlinearly changed decoded values; first ECC means receiving said nonlinearly decoded values and applying a first error correction operation thereon including correcting data signals based upon said first residues received with said data signals from said nonlinear decoder for supplying corrected output data signals; and second ECC means receiving said input coded values and generating an error detecting residue in accordance therewith; including compare means receiving said second ECC generated residue and a residue received from said input coded values for indicating any errors in said input coded values.

Claim 16

A decoding system for receiving input nonlinearly coded values including data and first check bit residues, the improvement including in combination: a nonlinear decoder converting said received input coded values into nonlinearly changed decoded values; first ECC means receiving said nonlinearly decoded values and applying a first error correction operation thereon including correcting data signals based upon said first residues received with said data signals from said nonlinear decoder for supplying corrected output data signals; and second ECC means receiving said input coded values and generating an error detecting residue in accordance therewith; including compare means receiving said second ECC generated residue and a residue received from said input coded values for indicating any errors in said input coded values.

Claim 17

The decoder set forth in claim 11 further including third ECC means operatively associated with said first ECC means and said nonlinear decoder means for detecting miscorrected errors by said first means and further including permutation means for altering a polynomial-to-data-set relationship, as between said first and third ECC means and said data.

Claim 18

The decoder set forth in claim 11 further including a nonlinear encoder receiving the corrected data signals from said first ECC means and re-encoding same into a nonlinear form similar to said input coded values; and said second ECC means receiving the nonlinearly encoded values from said nonlinear encoder rather than from said input coded value inputs.

Claim 19

The decoder set forth in claim 13 further including third ECC means operatively associated with said first ECC means and said nonlinear decoder for detecting miscorrected errors, and said residues associated with said first and third ECC means being supplied to said nonlinear encoder in the same manner as said corrected data signals.

Claim 20

A magnetic recording and reproducing system of the multitrack type having first and second portions respectively adapted for recording received signals and supplying readback signals, sets of such digital signals being exchanged with at least some of the tracks in parallel via a multitrack head, the improvement including in combination: first error detection and correction means (ECC-1 means) operatively associated with said first and second portions of said recorder and including predetermined permutation means interposed between said head and said error correction means, said head including two outer track scanning transducers, a first of said error correction means receiving signals from said outer transducers in relatively widely spaced nonadjacent input portions associated respectively with nonadjacent polynomial terms representing an error correction code on which the apparatus operation is based and further including that no adjacent tracks of said multitrack system exchange signals to any adjacent error correction inputs respectively representing adjacent terms of such code; second error detection means (ECC-2 means) also receiving data signals to be recorded or read back and having a relationship with respect to said tracks which is different from said relationship between said tracks and said polynomial of said first ECC means; one of said tracks being denoted as a check bit recording track, and said check bit recording track supplying and receiving signals from the lowest ordered polynomial position of both said first and second ECC means; and third ECC means receiving signals from and supplying signals to said tracks in a third permutation of polynomial-to-track relatioNships wherein no adjacent tracks are supplied to adjacent inputs representing adjacent terms of polynomial on which said third ECC means is constructed, and said outer ones of said transducers also being supplied to nonadjacent inputs representing nonadjacent terms of said polynomial.

Claim 21

A magnetic recording and reproducing system of the multitrack type having first and second portions respectively adapted for recording received signals and supplying readback signals, sets of such digital signals being exchanged with at least some of the tracks in parallel via a multitrack head, the improvement including in combination: first error detection and correction means (ECC-1 means) operatively associated with said first and second portions of said recorder and including predetermined permutation means interposed between said head and said error correction means, said head including two outer track scanning transducers, a first of said error correction means receiving signals from said outer transducers in relatively widely spaced nonadjacent input portions associated respectively with nonadjacent polynomial terms representing an error correction code on which the apparatus operation is based and further including that no adjacent tracks of said multitrack system exchange signals to any adjacent error correction inputs respectively representing adjacent terms of such code; second error detection means (ECC-2 means) also receiving data signals to be recorded or read back and having a relationship with respect to said tracks which is different from said relationship between said tracks and said polynomial of said first ECC means; one of said tracks being denoted as a check bit recording track, and said check bit recording track supplying and receiving signals from the lowest ordered polynomial position of both said first and second ECC means; and third ECC means receiving signals from and supplying signals to said tracks in a third permutation of polynomial-to-track relatioNships wherein no adjacent tracks are supplied to adjacent inputs representing adjacent terms of polynomial on which said third ECC means is constructed, and said outer ones of said transducers also being supplied to nonadjacent inputs representing nonadjacent terms of said polynomial.

Claim 22

The system set forth in claim 15 wherein signals exchanged with a first one of said outer transducers being supplied to three different input portions of each said ECC means respectively representing different ordered terms of three polynomials respectively defining said ECC means operations and signals exchange with a second one of said outer transducers being supplied to a different set of different input portions representing, respectively, three different polynomial terms and in differing orders in the respective ECC means.

Claim 23

The system set forth in claim 16 wherein each and every track of said multitrack system is applied to different input portions respectively representing different terms of polynomials in said ECC-1 and ECC-3 means.

Claim 24

The system set forth in claim 17 wherein said ECC-2 means has a predetermined polynomial input-portion-to-track relationship and said ECC-1 and ECC-2 means having their respective track-to-polynomial relationship different such that no track supplies input signals to the same input portion in said ECC-1 or ECC-3 means.

Claim 25

The system set forth in claim 18 wherein said ECC-1 means receives and supplies signals to the fifth track from its third position, to and from the seventh track from its sixth position, to and from the third track from its ninth position, to and from the eighth track from its first position, to and from the second track from its fifth position, to and from the first track from its eighth position, to and from track zero from its second position, to and from the sixth track from its fourth position, and to and from the fourth track from its seventh position, wherein tracks 4 and 5 are the outside tracks; and said ECC-3 means exchanging signals with the fifth track from its fourth position, the seventh track from its fifth position, the third track from the eighth position, the eighth track from its sixth position, the second track from the ninth position, the first track with the seventh position, track zero with the third position, the sixth track with the first position, and the fourth track from the second position.

Claim 26

The system set forth in claim 18 further including nonlinear means interposed between said data signals and one of said ECC means.

Claim 27

The system set forth in claim 20 wherein said nonlinear means is interposed between said ECC-1 means and said ECC-2 means and said ECC-2 means receives at least nonlinearly changed data signals.

Claim 28

The system set forth in claim 21 wherein said ECC-2 means receives the nonlinearly changed data signal plus the nonlinearly changed residues generated by said ECC-1 means.

Claim 29

The system set forth in claim 18 further including means on one of said ECC means operative with said recording system for selectively changing one of said permutation means.

Claim 32

The method set forth in claim 24 wherein said magnetic recording system is of the multitrack type, the method further including the following steps: treatIng outside ones of said tracks in a multitrack system as adjacent tracks insofar as exhibiting the same probability of error therebetween and exchanging signals between said outside tracks, any of said adjacent tracks, and at least one of said error correction means in a manner such that no signals exchanged with two adjacent tracks or said outside tracks are applied to input positions of said one error detection means that are mathematically nonadjacent with respect to a polynomial, the basis of which said error correction means is constructed, respectively.