Triple orthogonally interleaed error correction system

• US 5,392,299 A
• Filed: 01/15/1992
• Issued: 02/21/1995
• Est. Priority Date: 01/15/1992
• Status: Expired due to Term

• Current Assignee: Ampex Corporation (Delta Information Systems, Inc.), Emass LLC
• Original Assignee: Ampex Corporation (Delta Information Systems, Inc.), E-Systems Incorporated (Rtx Corporation)
• Inventors: McCoy, William D., Rhines, Don S., Handley, Kirk H.
• Primary Examiner(s): GORDON, PAUL P
• Application Number:
  US07/820,737
• Time in Patent Office: 1,133 Days
• Field of Search: 371/37.4, 371/37.5, 371/37.7
• US Class Current: 714/756
• CPC Class Codes: G11B 20/1866 by interleaving G11B20/1809 takes precedence
• CPC Class Codes: H03M 13/2703 the interleaver involving at least two directions
• CPC Class Codes: H03M 13/2764 Circuits therefore
• CPC Class Codes: H03M 13/29 combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
• CPC Class Codes: H03M 13/31 combining coding for error detection or correction and efficient use of the spectrum without error detection or correction H03M5/14 , H03M5/145

Abstract

The detection and correction of errors in digital data transmitted by or stored in a media channel is provided by processing the data through a triple orthogonally interleaved error correction system. On the transmit/store side of the system, the data is encoded three times prior to placement in the media channel with two different interleaving steps performed between the encoding steps. The first interleave is an orthogonal row shuffling interleave that provides enhanced protection against burst errors. On the receive/play back side, the data is decoded and deinterleaved, with included errors detected and corrected to enable recovery of the original data. To enhance the error correction, a circuit is used for generating a symbol accurate error flag identifying symbols containing errors thereby allowing the error correcting decoders to focus on and correct the data.

Claims

1. A method for interleaving and encoding a user data stream, comprising the steps of:

dividing the user data stream into a sequence of first code groups;

encoding each first code group in the sequence by appending thereto a first error correction code to form a first code word;

sequentially combining each encoded first code word according to the sequence of first code groups to output a sequence of first code words;

arranging the sequence of first code words into a first series of two-dimensional column by row data planes;

orthogonally interleaving the first series of data planes by inter-data plane row shuffling to form a second series of two-dimensional column by row data planes, each column of the second series of data planes comprising a second code group for sequential output;

encoding each second code group in the sequence by appending thereto a second error correction code to form a second code word;

sequentially combining each encoded second code word according to the sequence of second code groups to output a sequence of second code words;

arranging the sequence of second code words into a second code word two-dimensional column by row data plane, each row of the data plane comprising a third code group;

interleaving the arranged second code words in the second code word data plane by sequentially outputting the rows of the first data plane as a sequence of third code groups;

encoding each third code group in the sequence by appending thereto a third error correction code to form a third code word; and

sequentially combining each encoded third code word according to the sequence of third code groups to output a sequence of third code words as the interleaved and encoded user data stream.

2. The method as in claim 1 further comprising the step of encoding the sequence of third code words with a run-length limiting code.

3. The method as in claim 1 wherein the step of arranging the sequence of first code words comprises the step of sequentially storing an integral number of first code words in each column of the first series of data planes.

4. The method as in claim 3 wherein one first code word is stored in each column of the first series of data planes.

5. The method as in claim 1 wherein the step of arranging the sequence of second code words comprises the step of sequentially storing an integral number of second code words in each column of the second code word data plane.

6. The method as in claim 5 wherein one second code word is stored in each column of the second code word data plane.

7. The method as in claim 1 wherein the step of orthogonally interleaving by inter-data plane row shuffling comprises the step of shuffling the rows of the first series of data planes between data planes according to a predetermined shuffling algorithm to form the second series of a data planes while maintaining relative row position of a shuffled row between the first and second series of data planes.

8. The method as in claim 1 wherein:

the step of arranging the sequence of first code words comprises the step of sequentially storing one first code word per data plane column; and

the step of arranging the sequence of second code words comprises the step of sequentially storing one second code word per data plane column;

further comprising the step of arranging the sequence of third code words into a third code word two dimensional column by row data plane, one third code word sequentially stored per data plane row, such that the third error correction code is transverse to the first and second error correction codes.

9. The method as in claim 1 wherein the first and second series of data planes and the second code word data plane each comprise a pair of data storage buffers alternately available for reading and writing such that while a first buffer receives a portion of a sequence of uninterleaved code words for storage, a second buffer is outputting, in interleaved fashion, a preceding portion of a sequence as previously stored.

10. The method as in claim 1 further comprising decoding and deinterleaving the interleaved and encoded user data stream output as a sequence of third code words, the interleaved and encoded user data stream received as a sequence of fourth code words comprising the sequence of third code words with a total number of included data errors introduced therein, comprising the steps of:

decoding each fourth code word in the received sequence of fourth code words by detecting included data errors and correcting a first set number of data errors according to the appended third error correction code, each decoded fourth code word minus the third error correction code comprising a fourth code group combined according to the sequence of fourth code words for output as a sequence of fourth code groups substantially equal to the sequence of third code groups and including first erasure flags indicating each fourth code group in the sequence containing a detected but uncorrected error;

arranging the sequence of fourth code groups and first erasure flags into a fourth code group two-dimensional column by row data plane, each column comprising a fifth code word;

deinterleaving the sequence of fourth code groups and first erasure flags in the fourth code group data plane by sequentially outputting the columns of the data plane as a sequence of fifth code words and including deinterleaved first erasure flags;

decoding each fifth code word by detecting included data errors and correcting a second set number of data errors according to the appended second error correction code and the deinterleaved first erasure flags, each decoded fifth code minus the second error correction code comprising a fifth code group combined according to the sequence of fifth code words for output as a sequence of fifth code groups substantially equal to the sequence of second code groups including second erasure flags indicating each fifth code group in the sequence containing a detected but uncorrected error;

combining the first and second erasure flags to generate a third erasure flag pointing to locations within each fifth code group having data in error;

arranging the sequence of fifth code groups with the third erasure flags into a third series of two-dimensional column by row data planes;

orthogonally deinterleaving the third series of data planes by inter-data plane row unshuffling to form a fourth series of two-dimensional column by row data planes, each column of the fourth series of data planes comprising a sixth code word for sequential output and including deinterleaved third erasure flags;

decoding in sequence each sixth code word by detecting included data errors and correcting a third set number of data errors according to the appended first error correction code and the third erasure flags, each decoded sixth code word minus the first error correction code combined according to the sequence of sixth code words for output as a sequence of sixth code groups, wherein the sequence of sixth code groups are substantially equal to the sequence of first code groups comprising the user data stream.

11. The method as in claim 10 further comprising the steps of:

encoding the output sequence of third code words with a run-length limiting code; and

decoding the run-length limiting encoded sequence of third code words to generate the sequence of fourth code words that include data errors.

12. The method as in claim 11 further comprising the steps of:

detecting run-length errors in the sequence of run-length limiting decoded fourth code words; and

outputting the sequence of fourth code words including run-length erasure flags indicating detected run-length errors.

13. The method as in claim 12 wherein the step of decoding each fourth code word further includes the step of using the run-length erasure flags to enhance correction capability such that the sum of first, second and third set number of corrected errors substantially equals the total number of included data errors introduced into the sequence of third code words.

14. The method as in claim 12 further comprising the step of combining the run-length erasure flag and first erasure flag to generate a fourth erasure flag to assist in decoding each fifth code word, comprising the steps of:

delaying the run-length erasure flag to adjust for the processing needed to perform the step of decoding each fourth code word; and

logically combining the delayed run-length erasure flag in synchronization with the first erasure flag.

15. The method as in claim 10 wherein the steps of orthogonally interleaving and deinterleaving by interdata plane shuffling and unshuffling are opposite row shuffling operations such that each shuffled row in the third series of data planes is unshuffled and returned to a position in the fourth series of data planes corresponding to that position the row occupied in the first series of data planes.

16. The method as in claim 10 wherein the step of combining the first erasure flag and second erasure flag includes the steps of:

delaying the first erasure flag to adjust for an amount of processing time needed to perform the step of decoding fifth code words; and

logically combining in synchronization the delayed first erasure flag and the second erasure flag to generate the third erasure flag pointing to locations within each fifth code group having data in error.

17. The method as in claim 10 wherein the sequence of third code words are written into a media channel, further comprising the step of reading the media channel while writing thereto, comprising the steps of:

reading the sequence of third code words from the media channel after transmission thereto to provide the sequence of fourth code words which include a total number of channel introduced data errors;

dividing the sequence of fourth code words into predetermined portions;

counting the number of first erasure flags generated for each predetermined portion;

comparing the number of first erasure flags for each portion to a first threshold number; and

triggering a rewrite into the media channel of the user data stream corresponding to the portion of the sequence of fourth code words affected by errors exceeding the first threshold.

18. The method as in claim 17 wherein the step of triggering further comprises the steps of:

inhibiting further transmission of the user data stream; and

accessing a portion of the user data stream transmitted to the media channel corresponding to the portion of the sequence of fourth code words containing excessive errors for re-encoding, re-interleaving and writing into the media channel.

19. The method as in claim 17 further comprising the steps of:

counting the number of second erasure flags generated for each predetermined portion indicating the number of channel introduced errors in each portion of the user data;

comparing the number of second erasure flags to a second threshold number; and

triggering a rewrite into the media channel of the user data stream corresponding to the portion of the sequence of fourth code words affected by errors exceeding the second threshold.

20. Apparatus for interleaving and encoding a data stream divided into a sequence of first code groups, comprising:

first encoding means for calculating and appending a first error correction code to each first code group to form a first code word, each first code word combined according to the sequence of first code groups for output as a sequence of first code words;

means for orthogonally interleaving the sequence of first code words including means for sequentially storing the sequence of first code words into a first series of two-dimensional column by row data planes on a column by column basis, the first code words orthogonally interleaved by inter-data plane row shuffling according to a predetermined shuffling sequence to form a second series of two-dimensional column by row data planes, each column of the second series of data planes comprising a second code group for sequential output as a sequence of second code groups;

second encoding means for calculating and appending a second error correction code to each second code group to form a second code word, each second code word combined for output according to the sequence of second code groups as a sequence of second code words;

means for interleaving the sequence of second code words including means for sequentially storing the sequence of second code words into a second code word two dimensional column by row data plane on a row by row basis, each row comprising a third code group, the second code words interleaved by sequentially outputting rows of third code groups as a sequence of third code groups; and

third encoding means for calculating and appending a third error correction code to each third code group to form a third code word, each third code word combined to output a sequence of third code words representing the interleaved and encoded data stream.

21. The apparatus as in claim 20 further comprising means for encoding the sequence of third code words with a run-length limiting code.

22. The apparatus as in claim 21 wherein the means for encoding comprises a Miller-squared encoder.

23. The apparatus as in claim 20 wherein each of the first, second and third encoding means comprises a Reed-Solomon encoder.

24. The apparatus as in claim 20 wherein the means for storing of said means for orthogonally interleaving comprises first and second data storage buffers alternately available for reading and writing such that while the first buffer receives for storage a predetermined part of the sequence of first code words as a first series of data planes, the second buffer outputs a preceding part of the sequence of first code words as previously stored and having been orthogonally interleaved to form the second series of data planes.

25. The apparatus as in claim 24 wherein each data storage buffer comprises a plurality of two dimensional random access memories each holding at least one data plane.

26. The apparatus as in claim 20 wherein the row shuffling sequence maintains relative row location as the rows are shuffled between the series of data planes.

27. The apparatus as in claim 20 wherein the means for storing of said means for interleaving comprises first and second two-dimensional column by row data storage buffers alternately available for reading and writing such that while a predetermined part of the sequence of second code words are written into the columns of the first buffer, each row of the second buffer will be sequentially read to output a preceding part of the sequence of second code words previously stored in the columns of the first buffer.

28. The apparatus as in claim 20 wherein the sequence of third code words are written into a media channel, the media channel introducing data errors therein, further including a decoder and deinterleaver receiving from the media channel a sequence of fourth code words comprising the third sequence of code words with a total number of included data errors introduced therein, comprising:

first decoding means for detecting data errors and correcting a first number of included data errors in the sequence of fourth code words according to the third error correction code, the decoded fourth code words minus the third error correction code being output according to the sequence of fourth code words as a sequence of fourth code groups that include first erasure flags indicating fourth code groups containing detected but uncorrected data errors;

means for deinterleaving the sequence of fourth code groups and first erasure flags including means for sequentially storing the sequence of fourth code groups and first erasure flags into a fourth code group two-dimensional column by row data plane on a row by row basis, each column comprising a fifth code word, the sequence of fourth code groups deinterleaved by sequentially outputting the columns of the data plane as a sequence of fifth code words, including deinterleaved first erasure flags;

second decoding means for detecting data errors and correcting a second number of included data errors in the sequence of fifth code words according to the second error correction code and the first erasure flags, the decoded fifth code words minus the second error correction code output according to the sequence of fifth code words as a sequence of fifth code groups including second erasure flags indicating fifth code groups containing detected but uncorrected data errors;

means for combining the first and second erasure flags to generate a third erasure flag identifying locations within each fifth code group having uncorrected data errors;

means for orthogonally deinterleaving the sequence of fifth code groups including means for sequentially storing the sequence of fifth code groups and third erasure flags into a third series of two-dimensional column by row data planes on a column by column basis, the sequence of fifth code groups orthogonally deinterleaved by inter-data plane row unshuffling to form a fourth series of data planes corresponding to the first series of data planes, each column of the fourth series of data planes comprising a sixth code word, the columns of the fourth series of data planes sequentially output as a sequence of sixth code words, including deinterleaved third erasure flags;

third decoding means for detecting data errors and correcting a third number of included data errors in the sequence of sixth code words according to the first error correction code and the third erasure flags, the decoded fifth code words minus the first error correction codes output according to the sequence of sixth code words as a sequence of sixth code groups, wherein the sequence of sixth code groups are substantially equal to the sequence of first code groups comprising the data stream.

29. The apparatus as in claim 28 further comprising:

means for encoding the sequence of third code words with a run-length limiting code; and

means for decoding the run-length limiting encoded sequence of third code words to generate the sequence of fourth code words.

30. The apparatus as in claim 29 wherein the means for run-length limiting decoding further comprises means for detecting run-length errors in the sequence of fourth code words and outputting run-length erasure flags identifying included errors in the sequence of fourth code words.

31. The apparatus as in claim 30 further comprising means for combining the run-length erasure flag in synchronization with the first erasure flag comprising:

means for delaying the run-length erasure flag to adjust for the processing time of the first decoding means; and

means for logically combining the delayed run-length erasure flag and first erasure flag to generate a fourth erasure flag for processing by said second decoding means to identify error locations within the sequence of fourth code groups.

32. The apparatus as in claim 30 wherein the first decoding means uses the run-length erasure flags in addition to the third error correction codes to detect and correct additional errors in the sequence of fourth code words thereby enhancing error correction capability such that the sum of the first, second and third corrected errors substantially equals the total number of introduced data errors.

33. The apparatus as in claim 30 wherein the run-length limiting code comprises a Miller-squared code, and the means for encoding and decoding comprises a Miller-squared encoder and decoder, and wherein the means for detecting includes:

means for detecting and flagging short run data sequence violations in the sequence of channel decoded fourth code words;

means for detecting and flagging long run data sequence violations in the sequence of channel decoded fourth code words; and

means for detecting and flagging illegal Miller-squared sync sequences in the sequence of channel decoded fourth code words.

34. The apparatus as in claim 28 wherein the first, second and third encoding means comprise Reed-Solomon encoders and the first, second and third decoding means comprise Reed-Solomon decoders.

35. The apparatus as in claim 28 wherein the means for combining the first erasure flag and second erasure flag comprises:

means for delaying the first erasure flag as deinterleaved to adjust for the processing time of the second decoding means; and

means for logically combining the delayed deinterleaved first erasure flag in synchronization with the second erasure flag as output from the second decoding means to generate the third erasure flag identifying errors within the sequence of fifth code groups.

36. The apparatus as in claim 28 further including read-while-write means for the interleaved and encoded data stream to trigger a rewrite of the data stream containing excessive errors, comprising:

means for reading the sequence of third code groups while being written to the media channel to provide the sequence of fourth code words with introduced errors;

means, coupled to the third decoding means, for counting the number of generated first erasure flags indicating the number of detected errors in a predetermined portion of the data stream in the sequence of fourth code words;

means for comparing the number of first erasure flags to a first threshold number; and

control means for triggering a rewrite of the predetermined portion of the data stream affected by errors when the comparison indicates that the number of first erasure flags exceed the first threshold.

37. The apparatus as in claim 36 wherein the control means further comprises:

means for inhibiting further data stream transmission to the first encoder; and

means for accessing the predetermined portion of the data stream in error as stored in the first series of data planes of the means for orthogonally interleaving for re-encoding and re-interleaving the data stream.

38. The apparatus as in claim 36 further comprising:

means, coupled to the second decoding means, for counting the number of generated second erasure flags indicating the number of detected errors in the predetermined portion of the data stream in the sequence of fifth code words; and

means for comparing the number of second erasure flags to a second threshold number;

wherein the control means triggers a rewrite of the predetermined portion of the data stream affected by errors when the comparison indicates that the number of second erasure flags exceeds the second threshold number.

39. A method for interleaving and encoding a user data stream, comprising the steps of:

dividing the user data stream into a sequence of first code groups;

encoding each first code group in the sequence to append a first error correction code to form a first code word;

sequentially combining each encoded first code word according to the sequence of first code groups to output a sequence of first code words;

arranging the sequence of first code words into a first series of two-dimensional column by row data planes;

orthogonally interleaving the first series of data planes to form a second series of two-dimensional column by row data planes, each column of the second series of data planes comprising a second code group for sequential output;

encoding each second code group in the sequence to append a second error correction code to form a second code word; and

sequentially combining each encoded second code word according to the sequence of second code groups to output a sequence of second code words.

40. The method as in claim 39 wherein the step of orthogonal interleaving comprises the shuffling rows of the first series of data planes between data planes to form the second series of data planes such that each shuffled row maintains relative row position between the first and second series of data planes.

41. The method as in claim 39 further comprising the steps of:

arranging the sequence of second code words into a second code word two-dimensional column by row data plane, each row of the data plane comprising a third code group;

interleaving the arranged second code words in the second code word data plane by sequentially outputting the rows of the first data plane as a sequence of third code groups;

encoding each third code group in the sequence to append a third error correction code to form a third code word; and

sequentially combining each encoded third code word according to the sequence of third code groups to output a sequence of third code words as the interleaved and encoded user data.

42. Apparatus for interleaving and encoding a data stream, comprising:

first encoding means for receiving and encoding the data stream, the first encoding means dividing the data stream into a series of user code groups by appending, to each user code group, a first error correction code to output a series of first code words;

first interleaving means for receiving the series of first code words from the first encoding means and for orthogonally interleaving the series of first code words to output an orthogonally interleaved series of second code groups;

second encoding means for receiving and encoding the orthogonally interleaved series of second code groups by appending, to each second code group, a second error correction code to output a series of second code words;

second interleaving means for receiving the series of second code words from the second encoding means and for interleaving the second series of code words to output a series of third code groups; and

third encoding means for receiving and encoding the series of third code groups by appending, to each third code group, a third error correction code to output a series of third code words as the interleaved and encoded data stream.

43. The apparatus as in claim 42 further comprising media channel encoding means for receiving and encoding the series of third code words with a run-length limiting code.

44. The apparatus as in claim 42 wherein the first interleaving means includes means for sequentially storing the series of first code words into a first series of two-dimensional column by row data planes, one first code word stored per data plane column, the first code words orthogonally interleaved by inter-data plane row shuffling according to a predetermined shuffling sequence to form a second series of data planes with each column of the second series of two-dimensional column by row data planes comprising a second code group for sequential output.

45. The apparatus as in claim 44 wherein the means for storing in the first interleaving means comprises a pair of data storage buffers alternately available for reading and writing such that while a first buffer operates in a write mode to sequentially store a predetermined part of the series of first code words as the first series of data planes, a second buffer operates in a read mode to output a preceding part of the series of first code words as previously stored and orthogonally interleaved to form the second series of data planes.

46. The apparatus as in claim 45 wherein each data storage buffer comprises a plurality of two dimensional random access memories each holding at least one data plane.

47. The apparatus as in claim 42 wherein the second interleaving means includes means for sequentially storing the sequence of second code words into a first two-dimensional column by row data plane, one second code word per column, the second code words interleaved by sequentially outputting the rows of the first data plane with each row output comprising a third code group.

48. The apparatus as in claim 47 wherein the means for storing comprises a pair of two-dimensional column by row data storage buffers alternately available for reading and writing such that while a predetermined part of the series of second code words is sequentially written into the columns of a first buffer, a second buffer operates to sequentially read each row and output a preceding part of the sequence of second code words as previously stored in the columns of the buffer.

49. The apparatus as in claim 42 wherein the first, second and third encoding means comprise Reed-Solomon encoders.

50. The apparatus as in claim 42 further including means for decoding and deinterleaving a series of fourth code words, the series of fourth code words consisting of the series of third code words with included errors, comprising:

first decoding means for receiving the series of fourth code words, detecting errors and correcting a first number of errors in each fourth code word according to the third error correction code, the first decoding means further stripping the third correction code from each fourth code word to output a series of fourth code groups;

first deinterleaving means for receiving and deinterleaving the series of fourth code groups to output a series of fifth code words;

second decoding means for receiving the series of fifth code words, detecting errors and correcting a second number of errors in each fifth code word according to the second error correction code, the second decoding means stripping the second error correction code from each fifth code word to output a series of fifth code groups;

second deinterleaving means for receiving and orthogonally deinterleaving the series of fifth code groups to output a series of sixth code words; and

third decoding means for receiving the series of sixth code words, detecting errors and correcting a third number of errors in each sixth code word according to the first error correction code, the third decoding means stripping the first error correction code from each sixth code word to output a series of sixth code groups, wherein the series of sixth code groups are substantially equal to the series of first code groups comprising the data stream.

51. The apparatus as in claim 50 wherein further including means, associated with the first decoding means, for outputting a first erasure flag with each fourth code group indicating the existence of a detected by uncorrected error therein and the second decoding means includes means for utilizing the first erasure flags to enhance error correction capability therein.

52. The apparatus as in claim 51 further including:

means, associated with the second decoding means, for outputting a second erasure flag with each fifth code group indicating the existence of a detected but uncorrected error therein; and

means for logically combining, in synchronization, the first and second erasure flags to generate a third erasure flag identifying detected but uncorrected errors in each sixth code word;

wherein the third decoding means includes means for utilizing the third erasure flags to enhance error correction capability such that the sum of the first, second and third corrected errors substantially equals the number of included errors.

53. The apparatus as in claim 50 further including read-while-write means to trigger a rewrite of the encoded and interleaved data stream containing errors, comprising:

means for reading the series of third code words while being written to provide the series of fourth code words including data errors;

means, coupled to the first decoding means, for counting the number of generated first erasure flags indicating the number of included errors in a predetermined part of the series of fourth code words;

means for comparing the number of first erasure flags to a first threshold number; and

control means for triggering a rewrite of the data stream corresponding to the predetermined portion of the series of fourth code words affected by errors when the first threshold number is exceeded.

54. The apparatus as in claim 53 wherein the control means further comprises:

means for inhibiting further data stream transmission to the first encoding means during the rewrite of the affected data; and

means for accessing a part of the data stream corresponding to the predetermined part of the series of fourth code words including excess errors for re-encoding and re-interleaving.

55. The apparatus as in claim 53 further including:

means, coupled to the second decoding means, for counting the number of generated second erasure flags indicating the number of included errors in a predetermined part of the series of fifth code words;

means for comparing the number of second erasure flags to a second threshold number; and

wherein the control means triggers a rewrite of the data stream corresponding to the predetermined portion of the series of fifth code words affected by errors when the second threshold number is exceeded.

56. The apparatus as in claim 50 further comprising:

means for encoding the series third code words with a run-length limiting code; and

means for decoding the run-length limiting encoded series of third code words to generate the series of fourth code words.

57. The apparatus as in claim 56 wherein the means for decoding run-length limiting encoded code words further includes means for detecting and flagging run-length limiting errors in the series of fourth code words, and wherein the first decoding means includes means for receiving run-length limiting error flags to enhance error correction capability.

58. The apparatus as in claim 57 further including:

means for logically combining, in synchronization, the run-length limiting error flags and first erasure flags to generate a fourth erasure flag;

wherein the second decoding means includes means for utilizing the fourth erasure flags to enhance error correction capability of the means for decoding and deinterleaving.

59. The apparatus as in claim 57 wherein the run-length limiting code is a Miller-squared code, and the means for run-length limiting encoding and decoding is a Miller-squared encoder and decoder, and wherein the means for detecting includes:

means for detecting short run data sequence violations in the undecoded series of code words received from the media channel and outputting short run error signal;

means for detecting long run data sequence violations in the undecoded series of code words received from the media channel and generating long run error signal;

means for detecting illegal Miller-squared sync sequences in the decoded series of code words received from the media channel and generating sync sequence error signal; and

means responsive to the short run, long run and sync sequence error signals for outputting run-length limiting error flags identifying data locations in the series of channel decoded fourth code words in error.

60. Apparatus for interleaving and encoding a data stream divided into a series of user code groups, comprising:

first encoding means for receiving and encoding the user data, the first encoding means appending to each user code group a first error correction code to output a series of first code words;

interleaving means for receiving the series of first code words from the first encoding means and for orthogonally interleaving the series of first code words to output an orthogonally interleaved series of second code groups;

second encoding means for receiving the orthogonally interleaved series of second code groups and appending, to each second code group, a second error correction code to output a series of second code words.

61. The apparatus as in claim 60 wherein the interleaving means includes means for storing the series of first code words into a first series of two-dimensional column by row data planes, the first code words orthogonally interleaved by inter-data plane row shuffling according to a predetermined shuffling sequence to form a second series of data planes with each column of the second series of two-dimensional column by row data planes comprising a second code group for sequential output.

62. The apparatus as in claim 60 further comprising:

second interleaving means for receiving the series of second code words from the second encoding means and for interleaving the second series of code words to output a series of third code groups; and

third encoding means for receiving the series of third code groups and appending, to each third code group, a third error correction code to output a series of third code words for transmission onto a media channel as the interleaved and encoded user data.

63. The apparatus as in claim 62 wherein the second interleaving means includes means for storing the sequence of second code words into a second code word two-dimensional column by row data plane, the second code words interleaved by sequentially outputting the rows of the data plane with each row output comprising a third code group.