KR20010083258A - Method for correcting errors of digital data - Google Patents

Abstract

PURPOSE: A method of error correction in digital data is provided to enable design of an integrated circuit for high processing of error correction by dividing an inner parity and an outer parity included in received digital data and calculating syndromes respectively corresponding to the inner parity and the outer parity. CONSTITUTION: Frame portions are received and temporarily stored in an ECC(Error Correction Code) buffer(13) from a number of frames constituting an error correcting unit block. A syndrome calculator block(121) of an error correcting block(12) calculates an outer syndrome from the frame portions. An outer syndrome of the next frame portions is calculated, and the first calculated outer syndrome is corrected based upon the next calculated outer syndrome. The foregoing steps of calculation and correction are repeated until receiving the whole error correcting unit block. The error correcting block(12) performs outer error correction by using the corrected outer syndrome. A RAM controller(11) controls input/output between the error correcting block(12) and the ECC buffer(13) to output error-corrected digital data.

Description

{Method for correcting errors of digital data}

According to the present invention, when a signal recorded on a disc recording medium such as a DVD (Digital Versatile Disc) is read out and demodulated to original digital data, an error does not exist by correcting an error present in the demodulated digital data. The present invention relates to an error correction method of digital data that causes normal digital data to be output.

First, an ECC (Error Correction Code) block, which is an error correction unit of digital data, particularly an ECC block according to the DVD format, has 172 bytes of inner data and 10 bytes of inner parity (PI: Parity Inner). ) A total of 37,586 bytes corresponding to the product of 182 consecutive horizontal RS (Reed Solomon) codes, 192 bytes of outer data and 16 bytes of outer parity (PO: Outer Parity Outer). Has the size of.

Therefore, in order to temporarily store one ECC block, a memory of 37,586 bytes corresponding to the size of the ECC block is required, and in order to receive digital data continuously demodulated and output and to correct errors in units of ECC blocks, at least The two ECC blocks must be temporarily stored, so that the 37,586 bytes of memory are two. You will need 75,172 bytes of large memory.

Accordingly, recently, various error correction methods that can reduce the size of the memory required for error correction have been proposed from the related companies one after another, the error correction method proposed as described above in detail with reference to the accompanying drawings. do.

First, FIG. 2 illustrates a part of an optical disk apparatus to which the error correction method of the recently proposed digital data is applied as described above. The optical disk apparatus is a digital readout and demodulated output from a disk recording medium such as a DVD. An error correcting unit 2 for correcting an error of data; An ECC buffer (3) for temporarily storing the demodulated digital data; A PO buffer (4) for temporarily storing outer parity (PO) included in the digital data; The RAM control unit 1 which receives the demodulated digital data and controls data input / output between the error correction unit 2, the ECC buffer 3, and the PO buffer 4, and outputs error corrected normal digital data. Wherein the error correction unit 2 separately detects and transmits parity included in the digital data, and calculates a syndrome for providing an error of the digital data and providing the error information. Part 21; An error value / position calculation section 22 for calculating an error value and its error position based on the syndrome calculated and output from the syndrome calculation section 21; An ECC unit (23) for correcting an error of digital data temporarily stored in the ECC buffer (3) according to the error value and the error position calculated and output by the error value / position calculation unit (22); And a syndrome buffer 24 for temporarily storing the syndrome value calculated by the syndrome calculator 21.

As described above, the error correction method in the optical disk device is configured, first, when the digital data read out from the disk recording medium such as DVD and demodulated output is input to the RAM control unit 1, the RAM control unit 1, The ECC buffer 3 and the PO buffer 4 are controlled to separately store input and received digital data and outer parity. For example, the ECC buffer 3 has a size of 2,236 bytes, respectively. It consists of two SRAMs (31, 32) having a temporary storage of digital data excluding outer parity, the PO buffer 4 is composed of two SRAMs (41, 42) each having a size of 2,752 bytes The outer parity is temporarily stored.

On the other hand, the syndrome calculator 21 included in the error correction unit 2 detects parity included in the digital data received through the RAM control unit 1 and detects the error and error information of the digital data. The calculated syndrome is calculated, and the calculated syndrome value is temporarily stored in a syndrome buffer 24 including two SRAMs 241 and 242 each having a size of 2,752 bytes, and then the error value / position calculator 22 Is sent).

The error value / position calculation unit 22 calculates an error value of the digital data and its error position based on the received syndrome value, and then transmits the calculated error value and the error position to the ECC unit 23. The error value and the error position calculated as described above become the error value and error position of the digital data temporarily stored in the ECC buffer 3, and therefore, in the ECC unit 23, the RAM control unit 1 After reading the digital data temporarily stored in the ECC buffer 2 through the data, the error existing in the digital data is corrected based on the error value and the error position. Output digital data.

Thus, as described above, an ECC buffer 3 consisting of two SRAMs 31, 32 each having a size of 2,236 bytes, and two SRAMs 41, 42 each having a size of 2,752 bytes, Since error correction can be performed using only the memory capacity of the syndrome buffer 24 composed of the PO buffer 4 and the two SRAMs 241 and 242 each having a size of 2,752 bytes, that is, 15,480 bytes of memory. The memory capacity for correction can be greatly reduced.

However, as described above, the demodulated and output digital data, particularly the digital data corresponding to the ECC block, is composed of a total of 16 unit sectors, and one unit sector includes one inner parity as shown in FIG. 3. Since outer parity of one frame is received after interleaving for every 12 data frames, a PO buffer 4 for distinguishing and storing the outer parity is necessary, so that an integrated circuit for high-speed processing of error correction may be performed. There was a problem that greatly limited the design of the IC.

Accordingly, the present invention was created to solve the above problems, and can eliminate the use of an outer parity storage buffer used for error correction of digital data read and demodulated from a disc recording medium such as a DVD. It is an object of the present invention to provide an error correction method for digital data.

1 shows the configuration of an error correction (ECC) block,

2 illustrates a part of an optical disk apparatus to which the conventionally proposed error correction method is applied.

3 shows digital data in error correction block units;

4 shows a part of an optical disk apparatus to which the error correction method according to the present invention is applied;

FIG. 5 illustrates inner data and outer data corresponding to a unit sector.

FIG. 6 illustrates some configurations of some hardware for calculating the fractional outer syndrome according to the present invention.

※ Explanation of code for main part of drawing

1,11 RAM control unit 2,12 Error correction

3,13: ECC buffer 4: outer parity buffer

5,15: error correction 21,121: syndrome calculation unit

22,122: Error value / position calculation unit 23,124: ECC unit

The error correction method of digital data according to the present invention for achieving the above object, in the method for error correction of the error correction unit block interleaved outer parity, some of the plurality of frames constituting the error correction unit block Receiving the first step of calculating the outer syndrome; Calculating an outer syndrome of some frames received next, and correcting the calculated outer syndrome based on the outer syndrome; 3 steps of repeating the above step 2 until the entire reception of the error correction unit block; And four steps of performing outer air correction using the corrected outer syndrome.

Hereinafter, an error correction method of digital data according to the present invention will be described in detail with reference to the accompanying drawings.

First, FIG. 4 shows a part of an optical disk apparatus to which the error correction method of digital data according to the present invention is applied. As described above with reference to FIG. An error correcting unit 12 for correcting an error of digital data; An ECC buffer (13) for temporarily storing the demodulated digital data; And a RAM control unit 11 for receiving the demodulated digital data and controlling data input / output between the error correction unit 12 and the ECC buffer 13 to output error corrected normal digital data. The error correction unit 12 includes: a syndrome calculation unit 121 for separately detecting parity transmitted in the digital data and calculating a syndrome for providing an error of digital data and providing the error information; An error value / position calculation unit 122 for calculating an error value and an error position thereof based on the syndrome calculated and output from the syndrome calculation unit 121; An ECC unit (123) for correcting an error of digital data temporarily stored in the ECC buffer (13) according to the error value and the error position calculated and output by the error value / position calculation unit (122); And a syndrome buffer 124 for temporarily storing the syndrome value calculated by the syndrome calculator 21.

On the other hand, the syndrome calculation unit 121, the inner syndrome calculation unit 1211 for calculating the syndrome for the inner data, in particular the inner parity (PI) of the digital data received through the RAM control unit 11; An outer syndrome calculator 1212 that calculates a syndrome for outer data, in particular, outer parity PO, among digital data received through the RAM controller 11; A mux 1213 for selectively outputting the calculated inner syndrome and outer syndrome for each sector; And a syndrome buffer 124 for temporarily storing the calculated outer syndrome, which is received as described above through an error correction method in the optical disk device according to the present invention, in particular through the RAM controller 11. In the error correction method for distinguishing the inner parity and the outer parity included in the digital data to calculate the syndrome corresponding to each, it is possible to eliminate the use of the PO buffer 4 described above with reference to FIG. The detailed description is as follows.

First, the inner syndrome calculation unit 1211 receives inner data and inner parity of an ECC block through the RAM controller 11, calculates a syndrome for the inner parity, and calculates the calculated inner syndrome as the error value. The error correction operation by the ECC unit 123, that is, the error correction operation on the inner data, is performed to the position calculation unit 122. The inner data corrected as described above is illustrated in FIG. As shown in a), 13 inner frames, that is, one unit sector, are temporarily stored in the internal memory built into the RAM control unit 11. For reference, the RAM controller 11 includes two internal memories having a size of 2,236 bytes corresponding to one unit sector.

On the other hand, the RAM control unit 11, the outer syndrome calculation unit 1212 before the next unit sector is completed again, the outer data and outer parity corresponding to the unit sector consisting of 13 inner frames as described above The output will be sent to.

Accordingly, the outer syndrome calculation unit 121 calculates a syndrome for the outer parity, wherein the calculated outer syndrome is partially calculated as a fractional outer syndrome that is continuously calculated, and the syndrome buffer is calculated. It is sequentially updated and stored in the SRAM 1241 constituted at 124.

That is, as shown in (b) of FIG. 5, the fractional outer syndrome for the 172 outer frames in which 13 symbols are present is calculated, and the calculated fractional outer syndrome is converted into the SRAM 1241 of the syndrome buffer. By sequentially repeating the operation of updating and storing the data, the complete outer syndrome corresponding to 16 unit sectors, which is one ECC block, is calculated and outputted. In another SRAM 1242 constituting the syndrome buffer 124, Since the complete outer syndrome is calculated by repeating the above operation, it is output to the error value / position calculation unit 122, and the error correction by the ECC unit 123 is performed. Allow error correction to be performed.

On the other hand, the outer data received by the outer syndrome calculation unit 1211 is expressed as a polynomial as follows.

That is, if the polynomials are simply expressed as arithmetic expressions, the following equation 1 is obtained.

----------------------------- Equation 1

{R} _ {k}: kth symbol

{x} ^ {i}: i th position

Each outer syndrome, that is, 16 fractional outer syndromes for the outer data represented by the above arithmetic expression, may be calculated by 16 hardware configurations, as shown in FIG. The fractional outer syndrome calculated by the hardware is described as follows.

First, when input of data corresponding to the first unit sector is completed, 16 fractional outer syndromes for each frame are obtained from the 172 outer frames composed of 13 symbols, as shown in Equation 2 below. The fractional outer syndrome is stored in the SRAM 1241 configured in the syndrome buffer 124.

------------------------------ Equation 2

m = 0,1,2 ... 15

: Mth syndrome value for the first sector

a is the source of GF (2 ⁸ )

GF (2 ⁸ ): Galoa field

Then, when input of data corresponding to the second unit sector is completed, as described above, 16 fractional outer syndromes for each frame are obtained from 172 outer frames composed of 13 symbols, as shown in Equation 3 below. The calculated outer syndrome is thus calculated and updated as the fractional outer syndrome for the first unit sector previously calculated and stored, as shown in Equation 4 below.

------------------------------ Expression 3

------------------------ Expression 4

m = 0,1,2 ... 15

Subsequently, the above operation is repeated. When the last fractional outer syndrome calculated by the completion of input of data corresponding to the last 16th sector is calculated and updated as previously stored outer syndrome, the following equation is obtained. A complete outer syndrome such as 5 is calculated.

----------- Equation 5

As a result, since the complete outer syndrome calculated and updated as described above is output to the error value / position calculating unit 122, the error value / position calculating unit 122 determines the error value and the value based on the outer syndrome value. The error position is calculated, and the ECC unit 123 corrects an error of digital data temporarily stored in the ECC buffer 13 in accordance with the error value and the error position, and the RAM control unit 11 generates an error. The corrected digital data is output.

The error correction method of digital data according to the present invention as described above reads and demodulates from a disc recording medium such as a DVD, and distinguishes inner parity and outer parity included in the received digital data, respectively. By calculating the syndrome, it is possible to eliminate the use of the outer parity storage buffer used for error correction of digital data, which is a very useful invention that enables the design of an integrated circuit (IC) for high-speed processing of error correction.

Claims (2)

In the method for error correction of the error correction unit block interleaved outer parity, Calculating an outer syndrome by receiving some frames among a plurality of frames constituting the error correction unit block; Calculating an outer syndrome of some frames received next, and correcting the calculated outer syndrome based on the outer syndrome; 3 steps of repeating the above step 2 until the entire reception of the error correction unit block; And And four steps of performing outer air correction using the corrected outer syndrome. The method of claim 1, And the number of the partial frames is as many as at least one interleaved outer parity is included.