MXPA01001485A - Error correction encoding a data stream of information - Google Patents

Abstract

An apparatus for error correction encoding a datastream of information into blocks of error correction encoded information is disclosed, comprising an input terminal (20) for receiving the data stream of information. An error correction encoding unit (22) is present for carrying out an error correction encoding step on portions of said datastream of information so as to obtain said blocks of error correction encoded information, a block of error correction encoded information comprising a plurality of n sync blocks, each sync block comprising a sync word and a portion of said error correction encoded information, where n is a positive integer larger than 3. An output terminal (24) is present for supplying said blocks of error correction encoded information. In accordance withthe invention, the error correction encoding unit (22) is adapted to supply one of m mutually different sync words to each of said n sync blocks in said block of error correction encoded information, such that the sequence of two sync words of two subsequent sync blocks in the block of error correction encoded information is unique for each two subsequent sync blocks in the block of error correction encoded information, m being an integer for which holds 2<m<n.

Description

CORRECTING ERRORS CODING A CURRENT OF INFORMATION DATA The invention relates to an error correction apparatus coding an information data stream in blocks of error correction coded information, the apparatus comprising: - input means for receiving the information data stream, - coding means of error correction to carry out an error correction coding step in portions of said stream of information data to then obtain said blocks of error correction encoded information, a block of error correction encoded information comprising a plurality of synchronized "n" blocks, each synchronized block comprises a synchronized word and a portion of said encoded error correction information, where n is a positive integer greater than 3, - output means for providing said blocks of coded information of error correction. Said apparatus is known from WO 96/31880.

The known apparatus describes the generation of different synchronized words for the blocks synchronized in a block of encoded error correction information. This allows the identification of the position of a synchronized block of encoded error correction information. Instead, errors occur after receiving the encoded error correction information that can not be corrected in the error correction step that is normally available at the receiver.

The object of the invention is to improve the ability to correct errors.

According to the invention, the apparatus as defined in the introductory paragraph is characterized in that the error correction coding means is adapted to provide one of the mutually different synchronized words "m" to each of said synchronized blocks " n "in said encoded error correction information block, such that the sequence of the two synchronized words of two subsequent synchronized blocks in the encoded error correction information block is unique to each subsequent two synchronized blocks in the block of encoded information of error correction, "m" being an integer for which it has 2 < m < n. The invention is based on the following recognition. The synchronized words used to identify the synchronized blocks are usually unique bit patterns that do not occur anywhere in the serial data information stream. A further objective is to uniquely identify the exact position of a synchronized block in the selection of synchronized blocks "n" in the encoded error correction information blocks. This requires a plurality of mutually different synchronized words. Subsequently it should be noted that the error correction capability increases for the size increase of the error correction encoded information blocks: this means for an increasing number of blocks synchronized in a code block of error correction information. The identification of each block synchronized separately would mean as many synchronized words as there are synchronized blocks existing in a block of encoded error correction information. According to the invention, with the requirement that the sequence of two synchronized words of two subsequent synchronized blocks in the code block of error correction information be unique for each two subsequent synchronized blocks in the information block gateBgg .-- '. i ^ W' ^ »% i» 8 »á ^^^ K¿á» coded error correction, "differently" synchronized words are needed, so that more words are available for The information itself, while also improving the ability to correct errors The apparatus as defined in the opening paragraph can also be characterized in that the correcting coding means of letters are adapted to provide one of the synchronized words. mutually different "m * to each of said synchronized blocks" n "in said code block error correction information, such that each time two synchronized words of two synchronized blocks in the error correction encoded information block separated from each other by a synchronized block are unique to each group of two synchronized blocks in the coding information block of correction of errors, said two synchronized blocks are separated from each other by a synchronized block, "m" being an integer for which it has 2 <; m < n. This allows a reliable determination of the position of the detected synchronized block, even in case the synchronized word of this synchronized block is lost. The apparatus as defined in the opening paragraph may also be characterized in that the error correction coding means is adapted to provide one of the mutually different synchronized words "m" to each of said synchronized blocks "n" in said encoded information block of error correction, in such a way that each time two synchronized words of two synchronized blocks in the code block of error correction information separated from each other by two synchronized blocks are unique for each group of two synchronized blocks in the encoded information block of error correction, said two synchronized blocks are separated from each other by two synchronized blocks, "m" being an integer for which it has 3 < m < n. This allows a reliable determination *. $$ * «- '* - ^ z¿¡ & of the position of the synchronized block detecjilo, even in the case that the synchronized word of this synchronized block and the synchronized word of the previous or subsequent synchronized block were lost. elucidated with respect to the characterization said in the following description of the figure, in which: Figure 1 shows a block of encoded error correction information, including synchronized blocks of information; Figure 2 shows a characterization of the error correction coding apparatus; and Figure 3 shows a characterization of an error correction apparatus. Figure 1 shows a block 10 of encoded error correction information obtained by carrying out an error correction coding step, generally known in the art, in a portion of information input data stream. Block 19 comprises synchronized blocks "n" indicated SB ^ SB2, ..., SBn-1, SBn. Each synchronized block comprises a synchronized word, included in the first part FP1 in each of the synchronized blocks and the remaining part FP2 of the synchronized blocks is used to store portions of encoded information of error correction. A limited number of mutually different synchronized words "m" are used for incorporation into the first FP1 parts of each one of the synchronized blocks. In a characterization of the error correction encoded information block it is assumed that n = 31 and that 7 mutually different synchronized words are used for incorporation into the first FP1 parts of the 31 synchronized blocks. In the table provided below, the words synchronized for the 31 synchronized blocks of the error correction encoded information block «^ & t ^ m-é¿7 fe aBsai ÜÍ? - * are provided for four different characterizations. In all characterizations, 7 mutually different synchronized words are available, swO to sw6. As can be seen, in each characterization, the synchronized word swO is used for the first synchronized block of the encoded information block of error correction. The other synchronized words are used to identify the synchronized blocks numbered from 2 to 31 in the encoded error correction information block. Table 1: several sequences of synchronized words iZfim., ', u ?? taftate & ~ - It is presented that the apparatus of the invention generates the encoded error correction information blocks according to the selection of synchronized words in one of the columns provided below. From the examples shown above, it is clear that the selection of synchronized words satisfies the following rules: 1. A sequence of two synchronized words of two subsequent synchronized blocks in the error correction encoded information block is unique for every two blocks Subsequent synchronizations in the block of • encoded error correction information. An example: in the first characterization, the synchronized words of the synchronized blocks SB27 and SB28 are sw6 and swd. This sequence of two synchronized words occurs only once in the sequence of 31 synchronized words. In addition, preferably, also the sequence of the last word synchronized in a block of encoded information of error correction and the first word synchronized in the next block of encoded information of error correction is unique. 2. Each time two synchronized words of two synchronized blocks in the error correction coded information block, which are separated from each other by a synchronized block, are unique to each group of two synchronized blocks in the coded information block of each block. correction of errors separated from each other by a synchronized block. An example: in the second characterization, the synchronized words of the synchronized blocks SB13 and SB15 are sw1 and swd. This sequence of two synchronized words occurs only once for the synchronized words of the synchronized blocks that are separated from each other by a synchronized block in the encoded information block of error correction. This requirement is preferably also valid across the border between two blocks of coded error correction information. 3. Each time two synchronized words of two synchronized blocks in the error correction encoded information block separated from each other by two synchronized blocks is unique to each group of two synchronized blocks in the encoded information block of separate error correction one from the other by two synchronized blocks. An example: in the third characterization, the synchronized words of the synchronized blocks SB2 and SB5 are sw1 and sw2. This sequence of two synchronized words occurs only once for the synchronized words of blocks separated from each other by two blocks in the encoded information block of error correction. This requirement is preferably also valid across the boundary between two encoded information blocks of subsequent error correction. 4. Each time two synchronized words of two synchronized blocks in the error correction encoded information block that are separated from each other by three blocks are unique to each group of two synchronized blocks in the error correction encoded information block separated from each other by three synchronized blocks. An example: in the fourth characterization, the synchronized words of the synchronized blocks SB ^ and SB24 are sw2 and sw1. This sequence of two synchronized words occurs only once for the synchronized words of synchronized blocks separated from each other by three synchronized blocks in the encoded error correction information block. This preemption requirement is also valid across the boundary between two encoded information blocks of subsequent error correction.

During the reception of data stream comprising a selection of blocks of encoded error connection information, subsequent synchronized blocks of information are received. Three subsequent synchronized blocks, defined as Sb, -2, SbM, Sb "Sb, + 1 and Sb, + 2 have synchronized words defined as swa, swbl swc, swd and sw ?, respectively. - ^ Suppose that, on reception, the synchronized word of the synchronized block SB "is distorted and can not be identified. Assuming that the synchronized words swb and swd both equal sw2, and also assuming that the synchronized words satisfy the selection of words synchronized according to the first characterization, it can be established that the distorted synchronized word was sw3, and that the synchronized block of this distorted synchronized word was the synchronized block SB5. Now it is possible to store the data included in this synchronized block in the correct position in an error correction memory included in a receiver, so that then an error correction step can be carried out in the data stored in the memory. Suppose that, upon receipt, the synchronized words of the synchronized blocks SB, and SBI + 1 are distorted and can not be identified. Assuming that the synchronized words swb and swe equals sw3 and sw1, and also assuming that the synchronized words satisfy the selection of words synchronized according to the second characterization, it can be established that the distorted synchronized words were swd and sw1, and that the blocks synchronized of these distorted synchronized words were the synchronized blocks SB12 and SB13 respectively. It is now possible to store the data included in these synchronized blocks in the correct position in an error correction memory included in a receiver, so that then an error correction step can be carried out in the data stored in the memory. Suppose that, upon receipt, the synchronized words of the synchronized blocks SB,.?, SB, and SB, + 1 are distorted and can not be identified. Assuming that the synchronized words swa and swc equal sw1 and swd, and also assuming that the synchronized words satisfy the selection of words synchronized according to the third characterization, it can be established that the distorted synchronized words were sw3, sw1 and swd, and that the synchronized blocks of these distorted synchronized words were the synchronized blocks SB28, SB29 and SB30 respectively. Now it is possible to store the data included in these blocks synchronized in the correct position in an error correction memory included in a receiver, so that then an error correction step can be carried out in the data stored in the memory. It will be clear that, where necessary, this can be extended for the purpose of correcting more than three distorted synchronized words. Figure 2 shows schematically a characterization of the apparatus according to the invention. The error correction apparatus encoding an information data stream in blocks of error correction encoded information comprises an input terminal 20 for receiving the information data stream. The input terminal 20 is coupled to an input of a signal processing unit 22. The unit 22 is capable of carrying out an error correction coding step, well known in the art, in an incoming data stream. In addition, the unit 22 may be capable of carrying out a channel coding step, well known in the art, either before, but usually after, the error correction coding step, in the incoming data stream. . A coded data stream fl & »» 's ^ s &sfa error correction information is provided an enj? j || 24. In addition, a generator unit 2 (suitable for providing the plurality of mutually different synchronized words "m." The generation of a synchronized word can be carried out by directing a memory location in memory. a direction signal generated and provided via line 30. The unit 28 further provides a control signal via line 32 to the processing unit 22 to control the operation of the unit 22. The error correction coding unit 22 generates blocks of coded error correction information in response to said coding step of error correction carried out in portions of said stream of information data. As an example, a block of data words "w" times "v" of the current serial data information is subject to an error correction coding step, which results in the generation of "horizontal" parity words and "vertical" parity words. The words of pandad are placed in such a way that the encoded data blocks of error correction are created by comprising data words "m" times "n". The "n" selections of data words "m" each are set in the right-hand portion of figure 1, indicated by FP2 for each of the synchronized blocks "n". In addition each synchronized block comprises a synchronized word, "n" is a positive integer larger than 3. The error correction coding unit 22 is further adapted to provide one of the mutually different synchronized words "m" at each said blocks synchronized "n" in said encoded information block of error correction, so that the sequence of two synchronized words of two subsequent synchronized blocks in the block of encoded information of correction of errors is unique for every two subsequent synchronized blocks in the block ; -O & éSt a & ^ - * &2 í¡é ^ ll tf¿ & encoded error correction information, "m" being an integer for which it has 2 < m < n. In another characterization, the error correction coding unit 22 is further adapted to provide one of the mutually different synchronized words "m" to each of said synchronized blocks "n" in said coded error correction information block, such that each time two synchronized words of two synchronized blocks in the error correction encoded information block being separated a synchronized block apart from each other is unique to each group of two synchronized blocks in the coding information block of correction of errors being separated a separate synchronized block, m being an integer for which it has 2 < m < n. Again in another characterization, the error correction coding unit 22 is further adapted to provide one of the mutually different synchronized words "m" to each of said synchronized blocks "n" in said encoded error correction information block. , such that each time two synchronized words of two synchronized blocks in the error correction encoded information block separate two synchronized blocks apart from each other, it is unique for each group of two synchronized blocks in the coding information block of correction of errors separate two synchronized blocks apart from each other, m being an integer for which it has 3 < m < n. In this case "n" must be larger than 4. All the above requirements may also be valid across the boundary between two subsequent blocks of coded error correction information.

Furthermore, it should be noted that the apparatus can be provided with a channel coding unit 40 for carrying out a channel coding step in the information before, for example, recording the encoded data of error correction in a record carrier 44., as a magnetic record carrier, or an optical record carrier 46. The channel coding step is well known in the art. The step of adding the synchronized words can be carried out in the channel coding unit 40, instead of in the error correction coding unit 22. It should be noted here that the various requirements described above for the application of the mutually synchronized words different from the various synchronized blocks can be combined in one and the same characterization of the apparatus according to the invention. Figure 3 shows an error correction apparatus provided with an input terminal 50 for receiving the encoded error correction information blocks. These information blocks encoded error correction may have been obtained from reading information from a carrier records, as the conveyor magnetic registers 44 or the conveying optical record 46, by means of a reading unit and after carried out the step of channel decoding in reading information in a record carrier decoding unit 52. a channel error correction unit dd is available to perform a step of error correction information blocks det encoded error correction included in the signal provided via terminal 60, in order to obtain blocks of information corrected for errors. The error corrected information blocks are provided to an output terminal 68 as an information serial data stream. The device s 8 &? is provided with a detection unit 60 to detect mutually different synchronized words "m", where "m" is an integer smaller than "n". More specifically, the detection unit 60 is adapted to detect two synchronized words in the error correction encoded information blocks, said two synchronized words the synchronized words of the synchronized block i * and j being in a block of coded correction information. mistakes. The detected synchronized words are stored in a memory 62. This memory has at least three memory locations for storing the synchronized-detected words for three subsequent synchronized blocks in a coded error correction information block. When two subsequent synchronized words of two subsequent synchronized blocks i and j have been detected in an information block, the apparatus is able to identify the position of said synchronized block y and * * in said encoded error correction information block. This is done by means of a converter unit 64, which is able to convert the sequence of two successive synchronized words directly to a position information, indicating the position of the two synchronized blocks in the code block of error correction information. . The memory 62 has "p" memory locations for storing synchronized words of subsequent synchronized blocks "p", where "p" is equal to 3 or more. In the case of p = 3, the word synchronized in the second memory location may be erroneous, or it may not be detected at all. Again the position of this central synchronized block of three successive synpronized blocks corresponding to the three words synchronized in the memory 62 can be established in the converter unit 64, using the words synchronized at the first and third memory location of the memory 62.

In the case of p = 4, the words synchronized in the second and / or third memory location of the memory 62 may be erroneous, or may not be detected at all. Again the position of this second and / or third synchronized block of the four successive synchronized blocks corresponding to the four words synchronized in the memory 62 can be set in the converter unit 64, using the words synchronized in the first and fourth memory locations of the the memory 62. In the case of p = 5, the words synchronized in the second and / or third and / or fourth memory location of the memory 62 may be erroneous, or may not be detected at all. Again the position of this second and / or third and / or fourth synchronized block of the five successive synchronized blocks corresponding to the five words synchronized in the memory 62 can be established in the converter unit 64, using the words synchronized in the first and fifth memory location of the memory 62. Next, a different approach will be provided to determine the number of rows within a block of the synchronized numbers. The sequence of synchronized words as listed in feature 4 in the above table 1 will be used. - Assume that two synchronized numbers SR and SR-d have been detected, where R is the unknown row number and "d" is the distance (known) between synchronizations. - It seems convenient to redraw the synchronized numbers (see columns 4 and 5 of table 2) and divide the total block of 31 synchronized blocks into 6 sub-blocks of d rows and row 0. Now the synchronized numbers show a 3struct regular (as shown in column 6 of table 2). The synchronized OS disturbs the regular structure, which has to be counted for (dark gray areas in columns 8 through 10 in table 2). Note that all the additions in table 2 were made modulo 6. After, follow the procedure to determine the number of rows in the total block of two synchronized numbers and their distances: 1. Review for special cases: SR = 0 (before redrawing) SR = 2 and SR-4 = 5 (after to redraw, only when d = 4) 2.Calculate the difference = SR - SR-d (module 6) 3. Determine the relative row number "r" with the appropriate search table (see table 3) 4 Calculate nb. This is also the sub-block number "b" 5. Calculate the absolute row number: R = d * b + r + 1 With a brute force search table one would need 8 input bits (2 x 3 bits for synchronized numbers and 2 bits for distance) and 5 output bits. When this table is implemented in a ROM, 1280 bits will be required. With the method described above, 5 search tables are needed (4 shown in table 3 and one to redraw the synchronized numbers) with 3 input bits and 3 output bits. This requires 135 ROM bits plus some additional logic. fß¡? seA? ki ¿¿& * Table 2: General Perspective Table 3: Search tables that trace the differences? for the relative row number "r" While the invention has been described with reference to characterization there, it should be understood that these are not limiting examples. Therefore, several modifications may become apparent to those who are experts in the art, without departing from the perspective of the invention, as defined in the claims. In addition, any reference sign does not limit the perspective of the claims. The invention, as incorporated in the error correction coding apparatus, can be implemented by means of the hardware and software, and various "means" can be represented by the same hardware article. The word "comprises" does not exclude the presence of other elements or steps than those that are listed in a claim. Also, the word "a" or "an" before an element does not exclude the presence of a plurality of said elements. In addition, the invention lies in each of the novel features or combinations of features. "" "* ^ a» * e? ae. ~ j * Jai

Claims (17)

CHAPTER CLAIMING Having discovered the invention, it is considered as a novelty and, therefore, the content is claimed in the following:
1. CLAIMS 1. Apparatus for correcting errors coding a stream of information data in blocks of encoded error correction information, the apparatus comprises. - input means for receiving the information data stream, - error correction coding means for carrying out an error correction coding step in portions of said information data stream in order to obtain said blocks of encoded information of error correction, a block of error correction encoded information comprising a plurality of synchronized blocks "n", each synchronized block comprises a synchronized word and a portion of said encoded error correction information, where "n" is a positive integer greater than 3, - output means for providing said blocks of coded error correction information, characterized in that the error coding means is adapted to provide one of the mutually different synchronized words "m" for each of said synchronized blocks "n" in said coded information block of corr error correction, such that the sequence of two synchronized words of two subsequent synchronized blocks in the encoded error correction information block is unique to each of the two subsequent synchronized blocks in the error correction encoded information block , "m" being an integer for which it has 2 < m < n. j j & amp; amp; ^ & íS & UBt
2. 2. Apparatus for correcting errors coding an information data stream in blocks of error correction encoded information, the apparatus comprises: - input means for receiving the information data stream, - error correction coding means for carrying carrying out an error correction coding step in portions of said information data stream in order to obtain said blocks of error correction encoded information, a block of error correction encoded information comprising a plurality of synchronized blocks "n" , each synchronized block comprises a synchronized word and a portion of said encoded error correction information, where "n" is a positive integer larger than 3, - output means for providing said blocks of coded error correction information, characterized in which the means of coding errors are adapted s to provide one of the mutually different synchronized words "m" for each of said synchronized blocks "n" in said encoded error correction information block, such that each time two synchronized words of two blocks synchronized in the encoded information block of correction of errors separated from each other by a synchronized block is unique for each group of the two synchronized blocks in the code block of error correction information, said two synchronized blocks being separated from each other by a synchronized block , "m" being n integer for which it has 2 < m < n.
3. 3. Apparatus as claimed in claim 1, characterized in that the error correction coding means is further adapted to provide words synchronized to each of the synchronized blocks "n" in said encoded error correction information block, such as so that each time two synchronized words of two synchronized blocks in the error correction encoded information block separated from each other by a synchronized block are unique to each group of two synchronized blocks in the encoded error correction information block, said two synchronized blocks being separated from each other by a synchronized block.
4. 4. Apparatus for correcting errors coding a stream of information data in blocks of encoded error correction information, the apparatus comprises: - input means for receiving the information data stream, - error correction coding means for carrying carrying out an error correction coding step in portions of said information data stream in order to obtain said blocks of error correction encoded information, a block of error correction encoded information comprising a plurality of synchronized blocks "n" , each synchronized block comprises a synchronized word and a portion of said encoded error correction information, where "n" is a positive integer greater than 4, - output means for providing said blocks of coded error correction information, characterized in which the means of coding errors are adapted for providing one of the mutually different synchronized words "m" for each of said synchronized blocks "n" in said code block of error correction information, such that each time two synchronized words of two blocks synchronized in the encrypted information block of correction of errors separated from each other by a synchronized block is unique to each group of the two synchronized blocks in the error correction encoded information block, said two synchronized blocks being separated from each other by two synchronized blocks, ¥ being an integer for which he has 3 < m < n.
5. 5. Apparatus as claimed in claim 1 or 2, characterized in that the error correction coding means are further adapted to provide words synchronized to each of the synchronized blocks "n" in said encoded error correction information block, in such a way that each time two synchronized words of two synchronized blocks in the block of error correction coded information separated from each other by two synchronized blocks are unique for each group of two synchronized blocks in the coded information block of correction of errors separated from each other by two synchronized blocks.
6. 6. Apparatus as claimed in claim 1, characterized in that the error correction coding means is further adapted to provide words synchronized to each of the synchronized blocks "n" in said encoded error correction information block, such as so that each time two synchronized words of two synchronized blocks in the error correction encoded information block separated from each other by "p" synchronized blocks are unique to each group of two synchronized blocks in the coding information block of correction of errors separated from each other by "p" blocks synchronized apart from each other, where "p" is an integer larger than 2.
7. 7. Apparatus as claimed in claim 1, 2 or 4 characterized in that the error correction coding means are further adapted to provide a specific word of said synchronized words "m" only to the first synchronized block of said synchronized blocks "n" in each of said blocks of coded error correction information.
8. 8. Apparatus as claimed in claim 1, 2 or 4 characterized in that the error correction coding means are further adapted * to carry out a channel coding step in either an information data stream or in the current of encoded data correction of information errors.
9. 9. Apparatus as claimed in claim 1, 2 or 4 characterized in that it further comprises means for inscribing said blocks of coded error correction information in a record carrier.
10. 10. Apparatus as claimed in claim 1, 2 or 4, characterized in that the error correction coding means are further adapted to provide a word synchronized to each of the synchronized blocks "n" in said coding information block of correction of errors, in such a way that the sequence of two synchronized words of the last block synchronized in the code block of error correction and the first block synchronized in the next code block of error correction information is unique for every two synchronized blocks subsequent in the said two blocks of error correction coded information.
11. 11. Apparatus as claimed in claim 1, 2 or 4, characterized in that the error correction coding means are further adapted to provide a word synchronized to each of the synchronized blocks "n" in said coding information block of correction of errors, in such a way that a group of two synchronized words, a block synchronized in the block of information encoded of correction of errors and the other in the next block of information encoded of correction of errors and being separated by synchronized blocks "q" be unique for each group of two synchronized blocks in the two blocks of error correction encoded information, said two synchronized blocks being separated from each other by synchronized blocks "q", where "q" is an integer larger than 1.
12. 12. Method for carrying out the error correction coding in the apparatus as claimed in claim 1, 2, 4, 8 or 9.
13. 13. Record transporter having encoded error correction information blocks registered in a route of said record carrier, obtained with the apparatus as claimed in claim 9.
14. 14. Apparatus for error correction blocks of coded error correction information in an information serial data stream, an error correction coded information block comprising a plurality of synchronized blocks "n", each synchronized block comprising a synchronized word and a portion of said coded error correction information, where "n" is a positive integer greater than 3, the apparatus comprises: - input means for receiving the information data stream, - input means for receiving the blocks encoded error correction information, - error correction means for carrying out an error correction step in said code blocks error correction information to obtain blocks 5 of error corrected information, - output means for providing said blocks of error corrected information as a stream of serial information data, characterized in that said error correction means is adapted to detect mutually different synchronized words "m", where "m" is an integer 10 smaller than "n", the error correction means comprise the detection means for detecting two synchronized words in the error correction coded information blocks, said two synchronized words being the synchronized words of the synchronized block i * and jth in a block of information encoded of correction of errors, with the purpose of identifying the position of said block 15 synchronized i "1 and j * in said encoded error correction information block.
15. 15. Apparatus for error correction blocks of coded error correction information in an information serial data stream, an error correction coded information block comprising a plurality of synchronized blocks V, each synchronized block comprising a synchronized word and a portion of said coded error correction information, where "n" is a positive integer greater than 3, the apparatus comprises: - input means for receiving the information data stream, - input means for receiving the data blocks; encoded information of correction of 25 errors, _7 ÁsMsté ^^^ ^ t ^ Z ^^^^ ^^ ^^ tj ^ ^ ASi £ -¡? - error correction means to carry out an error correction step on said blocks of encoded information error correction for obtaining blocks of error-corrected information, - output means for providing said blocks of error-corrected information as a stream of serial information data, characterized in that said error correction means are adapted to detect mutually synchronized words different "m", where "m" is an integer less than "n", means error correction comprises means for detecting sync words "p" of subsequent sync blocks "p" in a block of coded information error correction, where "p" is an integer larger than 2, the detection means being adapted to identify the position of at least one central synchronized block of said synchronized blocks subsequent "p" using the detected synchronized words of the first and last synchronized blocks of said subsequent synchronized blocks "p" in said encoded error correction information block.
16. 16. Apparatus for error correction blocks of coded error correction information in an information serial data stream, an error corrected coded information block comprising a plurality of synchronized blocks "n", each synchronized block comprising a synchronized word and a portion of said encoded information error correction, where "n" is larger than 3 positive integer, the apparatus comprising: - input means for receiving the data stream of information, - input means for receiving the blocks information encoded error correction, - means error correction to perform a step of correcting errors in said information blocks encoded error correction for blocks of information corrected errors - output means for providing such blocks of information corrected for errors as a serial data stream of i nformation, characterized in that said error correction means are adapted to detect mutually different synchronized words "m", where "m" is an integer smaller than "n", the error correction means comprise the detection means for detecting two synchronized words in the error correction encoded information blocks, and the distance between said two synchronized words, expressed in synchronized block numbers, said two synchronized words being the synchronized words of the synchronized block i * and j * in a coded information block of error correction, for the purpose of identifying the position of said synchronized block i * and j * in said coding information block of error correction, using said two detected synchronized words and said distance.
17. 17. Apparatus as claimed in claim 16, characterized in that said identification step for identifying said position makes use of a conversion table.