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    Feedback error control arrangement
    1.
    发明授权
    Feedback error control arrangement 失效
    反馈错误控制布置

    公开(公告)号：US3605091A

    公开(公告)日：1971-09-14

    申请号：US3605091D

    申请日：1969-09-18

    Applicant: BELL TELEPHONE LABOR INC

    Inventor： TONG SHIH Y

    IPC: G06F11/16 ,  H04L1/12 ,  G06F11/10 ,  G08C25/02 ,  H04L1/10

    CPC classification number: H04L1/12 ,  G06F11/1625

    Abstract: A feedback error control arrangement for data transmission systems which have both forward and reverse channels is disclosed. Parity check digits for an information message are generated at a transmitting terminal and stored there while the information message only is transmitted via the forward channel to a receiving terminal. At the receiving terminal, parity check digits for the information message are again generated and sent back via the reverse channel to the transmitting terminal where they are compared with the parity check digits stored. If the parity digits agree, the next information message is transmitted. If they disagree, the first information message is retransmitted and a record is kept of the position in the data train of the retransmitted message. After all information messages have been sent, the record information is transmitted. Upon receipt of this information, the receiving terminal rewinds the tape and in accordance with the record information, sequentially locates and erases the incorrect messages.

    Random and burst error-correcting systems utilizing self-orthogonal convolution codes
    3.
    发明授权
    Random and burst error-correcting systems utilizing self-orthogonal convolution codes 失效
    使用自正交变换码的随机和爆发误差校正系统

    公开(公告)号：US3571795A

    公开(公告)日：1971-03-23

    申请号：US3571795D

    申请日：1969-06-09

    Applicant: BELL TELEPHONE LABOR INC

    Inventor： TONG SHIH Y

    IPC: H03M13/43 ,  H04L1/00 ,  G08C25/00 ,  H04L1/10

    CPC classification number: H04L1/0059 ,  H03M13/43

    Abstract: Sequences of information, encoded in a self-orthogonal convolution code of rate (b-1)/b and transmitted via a communication channel, are decoded to correct t random errors and bursts of B blocks where each block is b bits in length. The interconnections of the information digit shift registers of the encoder and decoder and their respective parity check digit generating circuits are determined by deriving a difference triangle of order lambda (b-1)t and of size (b-1) (t+1), partitioning the rows of the triangle into b-1 groups of t+1 rows each such that no more than t repetitions of any entry appear in each group, deriving a new difference triangle from each of the b-1 groups by inserting t-2 zeros at the top of the first column of each group and expanding the column into a difference triangle, and reconstructing each new triangle by multiplying each entry by B, and incrementing various entries until each entry of all triangles is different from all other entries of all triangles. The diagonal entries of the resulting triangles determine the interconnections.

    Character-error and burst-error correcting systems utilizing self-orthogonal convolution codes
    5.
    发明授权
    Character-error and burst-error correcting systems utilizing self-orthogonal convolution codes 失效
    使用自正交变换代码的字符错误和爆发错误校正系统

    公开(公告)号：US3593282A

    公开(公告)日：1971-07-13

    申请号：US3593282D

    申请日：1969-11-04

    Applicant: BELL TELEPHONE LABOR INC

    Inventor： TONG SHIH Y

    IPC: H04L1/00 ,  G06F11/12 ,  G08C25/00

    CPC classification number: H04L1/0059

    Abstract: Systems are disclosed for utilizing self-orthogonal convolution codes for correcting t character errors and certain burst errors. The elements or characters of the code words of the particular code utilized are elements of a finite field GF(p ). Information characters are encoded into the code and transmitted along with parity characters to a receiving terminal where they are there decoded to obtain the syndrome thereof. The number of nonzero elements in a portion SO, S1, ..., S2t 1 of the syndrome is then counted and if this number exceeds a threshold value t, it is assumed that errors have occurred in the block of characters being checked. The simultaneous equations Si Alpha r e1+...+ Alpha r i et are then solved for r1, ..., rt , and for e1, ..., et , where t'' is the number of errors in the block ranging from 1 to t, i 0,..., 2t-1, and Alpha is the primitive root of GF(p ). The number of errors t'' is determined as that t'' which satisfies t+1 or more of the equations Si. The values of r obtained from solving these equations identify the error positions in the received block of characters and each ei gives the value of the error in the corresponding error position ri. Each ei is then added to the character in position ri to thereby correct the erroneous characters.

    Double-character erasure correcting system
    6.
    发明授权
    Double-character erasure correcting system 失效
    双重刻蚀校正系统

    公开(公告)号：US3588819A

    公开(公告)日：1971-06-28

    申请号：US3588819D

    申请日：1968-09-18

    Applicant: BELL TELEPHONE LABOR INC

    Inventor： TONG SHIH Y

    IPC: H03M13/23 ,  H04L1/00 ,  G08C25/00 ,  H04L1/10

    CPC classification number: H04L1/0059 ,  H03M13/23

    Abstract: INFORMATION CHARACTERS OF L-BIT LENGTH ARE ENCODED IN A CONVOLUTION CODE OF RATE UP TO (2K-1)/2K, (WHERE 2 -1 IS AN EVEN MULTIPLE OF 2K-1) AND THEN TRANSMITTED OVER A COMMUNICATION CHANNEL TO A RECEIVING TERMINAL. THE RECEIVED CHARACTERS ARE PROCESSED TO (1) OBTAIN TWO PARTIAL SYNDROMES S0 AND S1 ASSOCIATED WITH THE TWO MOST RECENTLY RECEIVED BLOCKS OF CHARACTERS, EACH BLOCK CONTAINING 2 CHARACTERS, AND (2) DETERMINE CHARACTER ERASURES, I.E., THE POSITION OF ERRORS. DETERMINATION OF CHARACTER ERASURES IS DONE BY PERFORMING SIGNAL QUALITY CHECKS ON THE CHARACTERS SUCH AS NULLZONE DETECTION. THE TWO SYNDROMES SO AND S1 ARE THEN UTILIZED TO CORRECT THE CHARACTER ERASURES. SIGNAL-CHARACTER ERASURES IN ANY 2-CHARACTER BLOCK CAN BE CORRECTED WITHOUT THE REQUIREMENT OF A GUARD SPACE. IN ADDITION, DOUBLE-CHARACTER ERASURES IN ANY 2 -CHARACTER BLOCK CAN BE CORRECTED PROVIDED THE SUBSEQUENT BLOCK IS ERROR FREE.

    Automatic synchronization recovery for data systems utilizing burst-error-correcting cyclic codes
    7.
    发明授权
    Automatic synchronization recovery for data systems utilizing burst-error-correcting cyclic codes 失效
    用于数据系统的自动同步恢复利用爆发错误校正循环码

    公开(公告)号：US3571794A

    公开(公告)日：1971-03-23

    申请号：US3571794D

    申请日：1967-09-27

    Applicant: BELL TELEPHONE LABOR INC

    Inventor： TONG SHIH Y

    IPC: H03M13/17 ,  H03M13/33 ,  H04L7/04 ,  G06F11/12 ,  G08C25/00

    CPC classification number: H03M13/17 ,  H03M13/33 ,  H04L7/048

    Abstract: A method of providing automatic synchronization recovery in data transmission systems utilizing b-burst-error-correcting cyclic codes is disclosed. Synchronization recovery is accomplished by utilizing error patterns which, although not likely to occur in a transmission channel subject to burst error are nevertheless correctable by burst-error-correcting cyclic codes. In particular, the patterns utilized are those indicating that errors have occurred (simultaneously) at each end, but not the middle of the data word. By adding a specific preselected data sequence to each data word to be transmitted, subtracting the same fixed sequence from the received data sequences, and then decoding each resulting data word, such unlikely error patterns are obtained. These patterns indicate whether or not a synchronization gain or loss of up to b-2 symbols has occurred.

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