JPS6323274A - Data transmission method - Google Patents

Abstract

PURPOSE:To attain error correction satisfactorily even in case of increasing a data size, and to improve reliability for data, by changing error correction capacity by changing the length of an error correction code added on the data of each column of the data to be transmitted, corresponding to the quantity of the data to be transmitted. CONSTITUTION:A two-dimensional arrangement is formed by dividing the data to be transmitted into a prescribed number, and a first error correction code C1 having a prescribed length is added on the data of each row in the two dimensional arrangement, and also, a second error correction code C2 having the length corresponding to the quantity of the above stated data to be transmitted is added on the data of each column, and data transmission by every row is performed in order. The length of the second error correction code added in the columnar direction of the data to be transmitted arranged two- dimensionally, is set corresponding to the quantity of the data, then, the error correction capacity changes. It is possible to correct the data by the error correction code C2 in a columnar direction even when the data in the direction of a column, for example, an entire one row share is defective.

Description

[Detailed description of the invention] Hereinafter, the present invention will be explained in the following order.

A. Industrial field of application B0 Summary of the invention C4 Prior art 0 Problems to be solved by the invention E1 Means for solving the problems 23 Effects G. Example G-1. Explanation of data structure (Part 1) (Figure 1) G-2. Explanation of the disk format (Figure 2) G-3. Explanation of the recording/reproducing device (Figure 3) The present invention relates to a data transmission method suitable for use when transmitting data via a transmission (recording) medium with a relatively high error rate.

B0 Overview of the Invention The present invention is a data transmission method in which data to be transmitted is arranged two-dimensionally and the data is transmitted sequentially for each row, in which the length of the error correction code added in the column direction is made variable. In addition, the error correction ability is changed, so that sufficient error correction can be performed regardless of the data size, and the reliability of the data can be improved.

C8 Prior Art Conventionally, magneto-optical disks have been known as large-capacity recording media on which data can be rewritten.

In the case of magneto-optical disks, various types of additional information are added to the original data and recorded due to their large capacity.However, compared to hard disks, for example, pepper-stack errors occur relatively frequently, so the above-mentioned There is a risk that data and additional information may become unreadable. In order to prevent this, the applicant has previously filed the patent application No. 61-09389.
A data transmission method as disclosed in the specification and drawings of No. 2 is proposed. In this data transmission method, additional information is added to the end of the data to be transmitted, and this is arranged two-dimensionally to form a first error correction code for each row of data, and for each column of data. On the other hand, the error correction ability is improved by forming a second error correction code. Also, for example, the data size is IK (1024)
The data structure for bytes is 2 for 512 bytes.
It has a structure in which data is stacked above a dimensional array.

D1 Problems to be solved by the invention By the way, when handling large amounts of data such as image information,
Since a data size of about 512 bytes is small and inconvenient, it is desirable that the data size be as large as, for example, about 8 bytes, which is advantageous in terms of processing time and ease of processing.

However, as the data size increases, the probability that errors cannot be corrected increases and the reliability of the data decreases.

The present invention has been proposed in view of the above-mentioned conventional problems, and provides a data transmission method that can perform sufficient error correction and improve data reliability even when the data size is increased. The purpose is to provide a method.

Means for Solving the E0 Problem In order to achieve the above-mentioned purpose, the data transmission method according to the present invention divides the data to be transmitted into a predetermined number of parts.
Forming a dimensional array, adding a first error correction code of a predetermined length to data in each row of this two-dimensional array,
The present invention is characterized in that a second error correction code having a length corresponding to the amount of data to be transmitted is added to the data in each column of the two-dimensional array, and data is transmitted sequentially for each row.

F0 effect According to the present invention, the length of the second error correction code added in the column direction of two-dimensionally arranged data to be transmitted is set according to the amount of the data, and the error correction ability is improved. It's going to change.

G. Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In this embodiment, the present invention is applied to the case where data is transmitted (recorded/reproduced) via a magneto-optical disk.

G-1. Description of Data Structure In a magneto-optical disk, the standard unit data amount recorded in one sector data section is, for example, 512 bytes in consideration of use as an information recording medium for a computer. This data size (sector size) is 5
The data structure in the case of 12 bytes is as shown in FIG. 1(A).

In other words, the original data is data D. -5 of D511
The data D is 12 bytes. -D, 1 after 11
6 bytes of additional information is added, and this total is 528
The byte data is the actual data to be transmitted. This data is then divided into 48 bytes, 48 bytes in the row direction and 11 bytes in the column direction (48X11=
528), which are arranged two-dimensionally. In other words, it is a matrix array of 11 rows and 48 columns. Of the 16 bytes of additional information, 12 bytes are reserved for a reserved area, for example, link information to the next sector, data identification information, etc. are inserted. Furthermore, an error detection code EDC is generated for the 524-byte data including this reserved area, and inserted into the last 4-byte area of additional information.

Also, for each row of data in a 528-byte two-dimensional array including 4 bytes of this error detection code EDC, a length of 4
byte's first error correction code C8 (for example (52,4
8) Reed-Solomon code) is added, and a second 2-byte length code is added to each column of the above two-dimensional array.
An error correction code C2 (for example, a (13,11) Reed-Solomon code) is added to form a product code.

These data are sequentially written and read row by row in the row direction of a two-dimensional array (matrix array).

The read data is recorded in one sector of the disk. During this recording, a synchronization signal is inserted, for example, every row, or even every predetermined byte, to facilitate data synchronization during data processing on the reproduction side.

By the way, if a burst error occurs during reproduction of data recorded on a disk, data in the row direction of the two-dimensional array will be affected. However, even if the data in the row direction becomes a categorical item, for example, it can be corrected by the error correction code C2 in the column direction. According to the error correction code C2 having a length of 2 bytes, it is possible to perform 1-byte error correction and 2-byte erasure correction, and it is possible to correct about 2 lines.

On the other hand, in consideration of handling large amounts of data such as image information, for example, the data size (sector size) is 8K (8K).
192) The case of bytes will be explained. The data structure when the data size is 8 bytes is shown in FIG. 1(B).

That is, 16 bytes of additional information consisting of a 12-byte reserve area and a 4-byte error detection code EDC are added after the 8192-byte data D, ~D, , etc., making a total of 8208 bytes of data. Divided into 48 byte units, 48 bytes in the row direction and 17 bytes in the column direction.
It is arranged two-dimensionally as 1 byte (48×171=8208).

In addition, a first error correction code C1 (for example, (52,48) Reed-Solomon code) of 4 bytes in length is added to the data in each row of this 8208-byte two-dimensional array, and Length 1 for each column of data
6-byte second error correction code C, (for example (187
, 171) Reed-Solomon code) are added to form a product code.

In this way, comparing the case where the data size is 512 bytes and the case where the data size is 8 bytes, the length of the first error correction code CB + C'1 in the row direction is fixed at 4 bytes in both cases. On the other hand, the second error correction code in the column direction c2. For c', transmission (recording/
The length is set according to the amount of data to be played (i.e., 2 bytes for 512 bytes), 16 bytes for 8 bytes, and the error correction ability is changed. Even if the data size is increased, The probability that errors cannot be corrected does not increase, that is, the probability that errors can be corrected does not decrease, and sufficient error correction can be performed. According to the error correction code C-, which is 16 bytes long, it is possible to correct 8 bytes of errors and correct erasures of 16 bytes, and it is possible to perform 166 corrections, improving the reliability of data. can. Further, the redundancy when the data size is 8 bytes is approximately equal to that when the data size is 512 bytes, so there is no need to increase the redundancy.

G-2 Disc Format Description This will be explained with reference to FIG. 2. Data is recorded on the magneto-optical disk 11 by forming tracks 12 in a circular or spiral pattern, with one track per revolution. The track 12 of this disk 11 is made up of a plurality of sectors equally divided in the circumferential direction, and data, error correction codes, etc. having the above-described structure are recorded in each sector.

In this example, as shown in FIG. 2(A), the track consists of (n+1) sectors, for example, 32 sectors.

The format of data recorded in one sector is determined, for example, as shown in FIG. 2(B).

That is, one sector consists of a header section, a data section, and a gap section GAP provided after the header section and after the data section, respectively. In the header section, a preamble signal is recorded at the beginning, and an address signal AD consisting of a track address TA and a sector address SA is recorded.
D to which an error correction code FCC is added and an address synchronization signal ASYNC are added are repeated twice and recorded. Further, a preamble signal is recorded at the beginning of the data section, followed by a data synchronization signal DSYNC. Furthermore, the data synchronization signal DSYNCK is then transmitted, and the data and error correction code E having the structure shown in FIG. 1(A) or FIG. 1(B) is transmitted.
CC (C,, C2 or c,, C'2') and others are recorded.

G-3, Description of recording and reproducing device FIG. 3 is a block diagram showing an example of a recording/reproducing apparatus.

Recording is performed on the magneto-optical disk 11 as a spiral track, and tracking control is performed so that a recording/reproducing head (not shown) correctly scans the pre-formed track. disc 1
1 is rotationally controlled by a drive motor 21 so that it rotates at a predetermined speed with a constant angular velocity.

That is, this drive motor 21 is provided with a frequency generator 22, and the frequency generator 22 causes the motor 21 to
A frequency signal FC proportional to the rotational speed of is obtained, and this is supplied to the phase comparator circuit 23. On the other hand, this phase comparator circuit 23 is supplied with a speed reference signal REF. This speed reference signal REF should be recorded as described below.
Alternatively, it is a signal that can be changed depending on the transfer rate of data to be reproduced, and is equal to the frequency of the output FG of the frequency generator 22 when the disk 11 is rotating at a target rotational speed. However, a signal with a frequency similar to that obtained by dividing the output FC may also be used, and in that case, the output FG is of course also divided by the same frequency division ratio and supplied to the comparator circuit 23.

The comparison output of this phase comparison circuit 23 is passed through an integration circuit 24 and made into a speed error voltage, which is supplied to the motor 21 via a motor drive circuit 25 to drive the motor 2.
1 is controlled to rotate at an angular velocity according to the speed reference signal REF.

Next, the recording system will be explained. In addition to computer data, the digital data input terminal 31D receives data in which analog audio data is sampled at various predetermined sampling frequencies and each sample value is sampled as a word with a predetermined number of bits, and other various types of transfer data. Digital data of the rate is provided. The input terminal 31A has
An audio signal is supplied when the analog signal ψ is received.

When a digital signal is input to the digital signal input Koko 31D, a signal indicating the transfer rate may be sent together with the digital signal, and the signal indicating the transfer rate is supplied to the input terminal 31R.

Digital data from the input terminal 31D is supplied to the selector 33. Further, the analog signal from the input terminal 31A is converted into a digital signal by the A/D converter 32. The sampling frequency of this A/D converter 32 is, for example, 32IIG(z, 44.1KHz + 4
It is possible to switch to various frequencies such as 8KllHz, and one sample can be switched and output as words with various pit counts such as 8 bits, 12 pits, 16 pits, etc.

A digital signal from this A/D converter 32 is supplied to a selector 33. The selector 33 is connected to the input terminal 31D manually or by an external control signal.
Either the digital signal from the A/D converter 33 or the digital signal from the A/D converter 33 is selected.

The digital signal obtained by this selector 33 is supplied to the ECC encoder 34, and as described above, for example,
One sector worth of data is formed every two bytes or every eight bytes. At this time, if the digital data is 8 pins per word, one sector's worth of data is formed every 512 words or every 8 words, but if there are 12 pins,
In the case of digital data where one word is not 8 bits, such as 16 bits, one row cannot be made up of integer words in Figure 1, and one word may span two rows or even two sectors. This can be prevented by setting the number of bytes in the row direction to an appropriate value in the sector format data structure shown in FIG.

The data from the FCC encoder 34 is supplied to a recording process circuit 35, and after being subjected to appropriate modulation, it is supplied bit serially to the head and recorded on the magneto-optical disk 11.

The rotational speed of the disk 11 at this time is synchronized with the transfer rate of digital data to be recorded as follows. That is, during this recording, the switch 26 is connected to the terminal R.
The signal from the speed reference generation circuit 36 is switched to the EC side, and the signal from the speed reference generation circuit 36 is sent to the phase comparator circuit 2 as the speed reference signal REF.
3.

When the digital signal to be recorded is a digital signal from the input terminal 31D and is so-called self-clocking data, the data from the input terminal 31D is supplied to the speed reference generation circuit 36, and from this data The clock is extracted, the transfer rate is detected, and a speed reference signal corresponding to the detected transfer rate is output from this.

When the digital signal from the input terminal 31D is not a so-called self-clock signal, but a signal indicating the transfer rate separately from the data, such as a clock, this is supplied to the speed reference generation circuit 36 through the input terminal 31R. Then, a speed reference signal corresponding to the transfer rate detected from the signal indicating the transfer rate is outputted.

In addition, when the signal to be recorded is a signal obtained by sampling the analog signal from the input terminal 31A, the switch 37 is switched according to the selected sampling frequency and the number of bits for one sample, and the transfer rate is A speed reference signal is obtained from the speed reference generation circuit 36.

If the transfer rate of the digital signal from the input terminal 31D is known, but if neither self-clock data nor a signal indicating the transfer rate is sent, this switch 37 can be used to set the transfer rate. It is possible to select a reference signal according to the

The motor 21 is driven so that the speed reference signal corresponding to the transfer rate thus obtained and the frequency signal FG from the frequency generator 22 match in phase (frequency match), and the disk 11 rotates at a rotation speed synchronized with the transfer rate. Rotate with.

In this case, a signal identifying the transfer rate of the speed reference generation circuit 36 is supplied to the FCC encoder 34, and this transfer rate identification signal is recorded as part of the data identification information of the reserved area in FIG. Ru. Still, the sampling frequency and the focus number of the data word are also recorded as part of this identification information.

Incidentally, when the digital signal supplied to the input terminal 31D is FCC encoded with parity or other redundant focus added, these are decoded once to make only the original digital data.

Next, the reproduction system will be explained. The digital signal reproduced by the head from the disk 11 is sent to the reproduction process circuit 41.
The signal is then demodulated, focus-synchronized and reproduced, and converted into a digital signal. The output of this process circuit 41 is supplied to an identification information decoder (ID decoder) 46 to decode the signal indicating the transfer rate recorded in the reserved area of the additional data section of each sector, and the decoded output is used as the speed standard. A speed reference signal corresponding to the decoded transfer rate is obtained from the generation circuit 47, and this signal is supplied to the phase comparator circuit 23 through the playback side terminal PB of the switch 26, and the disc receives the recorded data. Rotates at a rotation speed synchronized with the transfer rate.

In this way, the data reproduced at a rotation speed synchronized with the data transfer rate is supplied to the FCC decoder 42 via the reproduction process circuit 41, where it is subjected to processing such as error correction on a sector-by-sector basis, and redundant bits are removed. If this is digital data, it is output to the output terminal 45D by the multiplexer 43, and if it is a digitized analog signal, it is converted back to an analog signal by the D/A converter 44 and output. Terminal 45A
is derived.

Note that although the above is a case where the rotation of the disk is controlled so that the rotational angular velocity is constant, it goes without saying that the present invention can also be applied to a case where the rotation of the disk is controlled so that the linear velocity is constant.

H1 Effects of the Invention As is clear from the description of the embodiments described above, according to the data transmission method of the present invention, the second error added to each column of the two-dimensionally arranged data to be transmitted is By changing the length of the correction code according to the amount of data to be transmitted, the error correction ability can be changed, and even if the data size is increased to about 8 bytes, sufficient error correction can be achieved. The reliability of the data can be improved.

[Brief explanation of drawings]

1 to 3 are diagrams for explaining an embodiment of the data transmission method according to the present invention, and FIG. 1 shows the data structure when the data size is 512 bytes and 8 bytes. 2 is a diagram showing an example of the format of a magneto-optical disk, and FIG. 3 is a block diagram showing an example of a recording/reproducing apparatus.

Claims (1)

[Claims] A two-dimensional array is formed by dividing data to be transmitted into a predetermined number of pieces, and a first error correction code of a predetermined length is added to data in each row of the two-dimensional array, and A data transmission method characterized by adding a second error correction code having a length corresponding to the amount of data to be transmitted to each column of data in the two-dimensional array, and sequentially transmitting data for each row. .