Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1998-02-12
2001-03-20
Baker, Stephen M. (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
Reexamination Certificate
active
06205568
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a data transmission system using a device for correcting errors in the received data and an error correcting method.
A conventional data transmission system, such as a disk reproducing device, comprises a receiving device
1
for receiving data, a temporary storage device
2
for storing the received data temporarily, an error correcting device
4
for correcting errors in the data temporarily stored, and a transmitting device
3
for transmitting the error-corrected data, as shown in FIG.
1
.
As an example of data, consider the data received in this order: [d
0,0
, d
0,1
, d
0,2
, . . . , d
0,M−1
, d
1,0
, d
1,1
, . . . , d
N−1,M−2
, d
N−1,M−1
] as shown in
FIG. 2
, and assume that error correction codes P (internal code) and Q (external code) consisting of product codes as shown in
FIG. 2
are added the data. In this case, information on the sensing of errors in the data codes using one correction code P, or the internal code, can be used for what is called an erasure correction using the other correction code Q, or the external code.
In the conventional system, the data recorded on a disk or the like is received by the receiving device
1
. The received data is stored in the temporary storage device
2
. An error correcting process using the error correction codes P and Q consisting of the product codes is performed on the data stored in the temporary storage device
2
.
Specifically, the data stored in the temporary storage device
2
is called back to the error correcting device
4
. The error correcting device
4
then executes a correcting process using the internal code P first. Because in the first correcting process, there is no error position information, erasure correction cannot be performed. In that case, the correcting process is performed on the data using only the internal code P and the result is stored in the temporary storage device
2
.
Then, the data is called back again from the temporary storage device
2
to the error correcting device
4
, which then performs a correcting process using the external code Q. In this correcting process, it is possible to perform erasure correction on the basis of information on the position of the error sensed in the correcting process of the internal code P, in addition to the correcting process using only the external code Q.
That is, with the conventional error correcting device, erasure correction cannot be performed in the first correcting process. After the first correcting process using the internal code P, however, when the correcting process using the external code Q is performed on the basis of information on the first correction, this achieves a sufficient correcting capability, even if erasure correction is not carried out in the first correcting process.
To do this, it is necessary to repeat the correcting process using the internal code P and the correcting process using the external code Q. Therefore, to perform error corrections at high speed, the data transfer rate between the error correcting device
4
and the temporary storage device
2
has to be increased.
An attempt to increase the data transfer rate between the error correcting device
4
and the temporary storage device
2
gives rise to an increase in the device size and in the power consumption resulting from the faster operation.
BRIEF SUMMARY OF THE INVENTION
The main object of the present invention is to provide a data transmission system capable of avoiding the problems of an increase in the power consumption and in the device size resulting from the faster operation needed for the repetition of error correcting processes using internal and external codes, by providing a data transfer device capable of performing erasure correction in a correcting process first carried out.
According to a first aspect of the present invention, there is provided a data transmission system comprising: a receiving device for receiving data to which a pair of error correction codes consisting of product codes is added, one error correction code having a data arrangement identical with the order in which the receiving device receives the data; a temporary storage device for storing the data temporarily; an error sensing device for sensing errors in one error correction code, before storing the data in the temporary storage device; an error correcting device for correcting errors in the data stored in the temporary storage device, the error correcting device executing erasure correction of the other error correction code by using information on errors in one error correction code sensed at the error sensing device; and a transmitting device for transmitting the data whose errors have been corrected by the error correcting device.
With this configuration, erasure correction can be performed in a correcting process first carried out at the error correcting device.
It is desirable that the error sensing device should be a syndrome computing device that calculates a syndrome for one of the pair of error correction codes consisting of product codes. It is also desirable that the error correcting device should perform erasure correction using a specific number of syndromes instead of using all of the syndromes for one error correction code. This could speed up the sensing process and the correcting process.
The application of the data transmission system to a DVD reproducing device or a CD-ROM device enables the system to exhibit its capability effectively.
According to a second aspect of the present invention, there is provided an error correcting method comprising: a first step of sensing errors in one error correction code received in the order in which data has been received of a pair of error correction codes consisting of product codes added to the data and then storing the data in a temporary storage device; a second step of calling back the other error correction code of the product codes added to the data from the temporary storage device and performing not only an error correcting process using only the other error correction code but also erasure correction on the basis of information on the errors in one error correction code sensed in the first step; and a third step of correcting the data stored in the temporary storage device.
It is desirable that the error correcting method should further comprise: a fourth step of calling back the one error correction code for the data from the temporary storage device; a fifth step of performing not only an error correcting process using only the one error correction code but also erasure correction using information on errors in the other error correction code; a sixth step of correcting the data stored in the temporary storage device; a seventh step of calling back the other error correction code from the temporary storage device; an eighth step of performing not only an error correcting process using only the other error correction code but also erasure correction on the basis of information on errors in the one error correction code; and a ninth step of correcting the data in the temporary storage device.
Furthermore, it is desirable that the fourth step to the ninth step should be repeated according to the error correcting capability needed.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
REFERENCES:
patent: 4476562 (1984-10-01), Sako et al.
patent: 4680764 (1987-07-01), Suzuki et al.
patent: 4785451 (1988-11-01), Sako et al.
patent: 5392299 (1995-02-01), Rhines et al.
patent: 5463640 (1995-10-01), Cloetens
patent: 5974580 (1999-10-01), Zook et al.
Baker Stephen M.
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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