Error detective information adding equipment

Details Error detective information adding equipment Error detective information adding equipment

1998-12-01

2001-06-26

Decady, Albert (Department: 2133)

Error detection/correction and fault detection/recovery

Pulse or data error handling

Error/fault detection technique

Reexamination Certificate

active

06253349

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an error-detecting information adding apparatus for adding error-detecting information to data to be recorded onto recording mediums in a system for recording data onto recording mediums or to data to be transferred in a communications system.
BACKGROUND OF THE INVENTION
Recently, great efforts have been made to develop efficient techniques for digitizing information and recording or communicating large amounts of digitized data. In conjunction with the efforts, techniques for increasing the reliability of data have also been improved.
A known technique of this field has succeeded in increasing the reliability of the data by adding error-correcting codes to the data.
This technique deals with errors which may happen in data transfers via communication paths, such as data read errors due to minor flaws, stains, or dusts on mediums like optical discs, and deals with data reception errors due to multipath fading in communications. In this technique, error-correcting codes are previously added to data before the data is recorded onto recording mediums or transmitted via communications. The added error-correcting codes are used to correct the data when the data is read by data reading apparatuses from the recording mediums or received by data receiving apparatuses via communications.
Another technique has also been developed to deal with errors which cannot be corrected with the error-correcting codes. In the other technique, data recording or transmitting apparatuses further add error-detecting codes so that errors due to the error correction can be detected.
A conventional technique for adding error-detecting codes to data used in a process of recording data in a conventional optical disc recording system is described below with reference to
FIGS. 1-5
.
FIG. 1
shows a construction of a conventional optical disc recording system
9000
.
The conventional optical disc recording system
9000
receives data from an external host apparatus
9900
, adds headers, error-detecting codes, and error-correcting codes to the received data, modulates the data, and writes the modulated data onto the DVD. The conventional optical disc recording system
9000
includes a bus
9001
, a microcomputer
9010
, a DMA controller
9020
, an input interface unit
9030
, a scramble unit
9040
, an EDC generation unit
9050
, a buffer interface unit
9060
, a buffer memory
9061
, an ECC generator
9070
, a modulating unit
9080
, and an optical disc recording unit
9090
.
The DVD is an optical disc. Hereinafter, the DVD is called optical disc. Also, of the data transferred from the external host apparatus
9900
to be recorded in the optical disc, an amount of data corresponding to a data field which will be described later is called original data. Therefore, it may happen that the external host apparatus
9900
transmits a plurality of pieces of original data.
Now, the construction of information to be recorded onto the optical disc is described below.
FIG. 2
shows a configuration of the data sector.
FIG. 3
shows a configuration of the ECC block.
Here, the data sector is a unit of data standardized for the DVD, and the ECC block is a unit of data used in adding error-correcting codes, where ECC stands for Error-Correcting Code.
As shown in
FIG. 2
, each data sector is composed of a header field, a data field, and an EDC (Error-Detecting Code). As shown in
FIG. 3
, each ECC block is composed of 16 data sectors and two kinds of error-correcting codes: an inner parity correcting code, and an outer parity correcting code. The error-correcting codes are product codes by the Reed-Solomon codes.
The header field is composed of an ID code, an error-correcting code (IEC) related to the ID code, and a reserve area. The ID code is address information related to the current data sector.
The data field is composed of 2,048 bytes of data which is the original data having been subjected to a scramble which will be described later.
The components of the optical disc recording system
9000
are described below (see FIG.
1
).
The microcomputer
9010
, including a ROM storing a program to be executed, controls the entire operation of the optical disc recording system
9000
by receiving data transfer notifications from the external host apparatus
9900
. The microcomputer
9010
also generates headers to be attached to the original data and writes the generated headers into the buffer memory
9061
.
The DMA controller
9020
receives addresses of the transfer source and transfer destination from the microcomputer
9010
and transfers data between the buffer memory
9061
and other units in the level of hardware.
The input interface unit
9030
, being achieved by an SCSI interface or the like and connecting the external host apparatus
9900
to the optical disc recording system
9000
, has a function of transferring a data transfer notification from the external host apparatus
9900
to the microcomputer
9010
. The input interface unit
9030
, including a FIFO buffer
9031
for storing a certain amount of data which makes up the original data, receives the original data from the external host apparatus
9900
.
The scramble unit
9040
subjects the original data to the scramble.
The term “scramble” used here indicates arranging data elements of the data sequence on a pseudo random basis. That is, the scramble is a process performed to prevent the amount of information on amplitude change points from decreasing by setting the same probability of occurrence for data “1” and data “0.” With this process, it is possible for the optical disc playback side to prevent occurrence of a problem that the playback side which reads the data sequences from the optical disc fails to extract the timing elements from the data sequences and fails to play back the data sequences. It should be noted here that in a data transmitting/receiving system, the transmitting side subjects the data sequences to the scramble before transmission so that the receiving side surely receives the data sequences.
The EDC generation unit
9050
generates error-detecting codes corresponding to the original data.
The ECC generator
9070
generates error-correcting codes corresponding to data (see FIG.
3
).
The modulating unit
9080
modulates data digitally. The optical disc recording unit
9090
records data onto the optical disc by irradiating laser rays onto the optical disc from the laser light source.
The buffer memory
9061
is a RAM for storing the headers, original data, error-detecting codes, and error-correcting codes. The buffer interface unit
9060
controls reading and writing of data from and into the buffer memory
9061
.
The operation of a conventional optical disc recording system is described below with reference to
FIGS. 4 and 5
.
FIG. 4
is a flowchart showing the operation of a conventional optical disc recording system
9000
.
FIG. 5
is a flow diagram showing data flow in the conventional optical disc recording system
9000
in which error-detecting codes are finally stored in the buffer memory
9061
.
Note that
FIG. 5
shows data being transferred in unit of one data sector.
In the optical disc recording system
9000
, the FIFO buffer
9031
in the input interface unit
9030
receives the original data from the external host apparatus
9900
({circle around (
1
)} in FIG.
5
). On receiving information on the address setting and the like from the microcomputer
9010
, the DMA controller
9020
transfers the original data from the FIFO buffer to the buffer memory
9061
(step S
9101
, {circle around (
2
)} in FIG.
5
). After this step, the buffer memory
9061
stores data which is the content of the data field.
After the content of the data field is stored in the buffer memory
9061
, the microcomputer
9010
generates the header field (see FIG.
2
), and writes the created header field into the buffer memory
9061
(step S
9102
, {circle around (
3
)} in FIG.
5
). After this step, the buffer memory
9061
stores the header field.
After the header field is stored in the buffer memor

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