Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1998-02-11
2002-03-12
Decady, Albert (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C714S807000
Reexamination Certificate
active
06357031
ABSTRACT:
This application claims the benefit of Korean Patent Application No. 4407/1997, filed in Korea on Feb. 14, 1997, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a serial data transmission apparatus, and more particularly, to an improved serial data transmission apparatus which is capable of enhancing operational speed and is well adapted for serial data transmission using a cyclic redundancy checking (CRC) method. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for serially transmitting a large amount of data. The present invention also relates to a corresponding method for serially transmitting data.
2. Discussion of Related Art
FIG. 1
illustrates a conventional serial data transmission apparatus. As shown therein, the conventional serial data transmission apparatus includes a transceiver
10
and a receiver
20
.
The transceiver
10
includes a data storing unit
11
for storing source data to be transmitted and a data checking unit
12
for checking the data from the data storing unit
11
based on a cyclic redundancy checking (CRC) method. The transceiver
10
also includes a data combining unit
13
for combining the outputs from the data storing unit
11
and the data checking unit
12
to generate new data. The transceiver
10
further includes a data encoding unit
14
for encoding the data output from the data combining unit
13
using a non-return-zero-inverted (NRZI) method and serially transmitting the encoded data via a channel.
The receiver
20
includes a data decoding unit
21
for receiving and decoding the NRZI type data transmitted from the transceiver
10
and a data separation unit
22
for separating the data from the data decoding unit
21
to restore it to the form before the data combination by the transceiver
10
. Also, the receiver
20
includes a data storing unit
23
for temporarily storing the source data separated by the data separation unit
22
, a data checking unit
24
for checking the output from the data storing unit
23
based on the CRC method, and a data comparison unit
25
for comparing the data in order to judge whether the output from the data checking unit
24
and the detection data separated by the data separation unit
22
are identical.
The operation of the conventional serial data transmission apparatus will now be explained with reference to the accompanying drawings.
First, the data storing unit
11
of the transceiver
10
outputs source data D
1
to the data checking unit
12
. Then, the data checking unit
12
checks the data D
1
based on the CRC method and outputs the detection data d
1
.
Here, the data D
1
through Dn are outputted from the data storing unit
11
in a packet-format. In addition, the cyclic redundancy checking (CRC) method employed in the data checking unit
12
is a method of checking whether the data is transmitted without an error. This is accomplished by dividing a k-bit binary data M by an (n+1)-bit data P to produce an n-bit residual F and attaching the n-bit residual F to the front of the k-bit binary data M when transmitting the k-bit binary data M. Then, the combined (n+k)-bit data is output to the next circuit block which checks whether a residual is produced when the (n+k)-bit combined data is divided by the (n+1)-bit data P. If no residual is produced by the division, the transmission of the k-bit data M is judged to have been performed without an error.
In addition, the data combining unit
13
combines the data D
1
from the data storing unit
11
and the detection data d
1
from the data checking unit
12
, and generates a new data (D
1
+d
1
). The data (D
1
+d
1
) is not to be confused as a mathematical sum of the data D
1
and d
1
. Instead, the data (D
1
+d
1
) is generated by combining the bits of the data D
1
and d
1
, i.e., attaching the data d
1
to the end of the data D
1
as shown in FIG.
2
. The data combining unit
13
, as shown in
FIG. 2
, changes the data D
1
and d
1
having different lengths A and B, respectively, into a new (A+B)-bit data (D
1
+d
1
).
The data encoding unit
14
encodes the data (D
1
+d
1
) by the non-return-to-zero-inverted (NRZI) method. The encoded data (D
1
+d
1
)′ is transmitted to the receiver
20
.
As shown in
FIG. 3
, the non-return-to-zero-inverted (NRZI) method is a data encoding method for changing the magnetized state of the encoded data only at falling edges, i.e., when the source data changes the state from 1 to 0, thus generating a different type of data. The method may also be set to change the magnetized state of the encoded data only at rising edges.
In addition, the data decoding unit
21
of the receiver
20
decodes the transmitted data (D
1
+d
1
)′ to restore the original form of the data (D
1
+d
1
) and outputs the data to the data separation unit
22
. The data separation unit
22
separates the data (D
1
+d
1
) into the source data D
1
and the detection data d
1
, and outputs the separated data D
1
and d
1
.
The source data D
1
separated by the data separation unit
22
is transmitted to the data checking unit
24
through the data storing unit
23
. The data checking unit
24
checks the source data D
1
based on the CRC method and outputs a different detection data d
1
′.
The data comparison unit
25
decides whether the detection data d
1
′ output by the data checking unit
25
and the restored detection data d
1
separated by the data separation unit
22
are identical.
If the detection data d
1
and d
1
′ are judged to be identical, namely if it is judged that the source data D
1
transmitted from the transceiver
10
to the receiver
20
is correct, the data comparison unit
25
outputs a first signal. In response to the first bit signal, the transceiver
10
transmits the next data D
2
to the receiver
20
, and the source data D
1
is outputted from the data storing unit
23
. Here, the first bit signal has a value of 0 or 1.
In contrast, if the detection data d
1
and d
1
′ are judged not to be identical, the data comparison unit
25
outputs a second bit signal. In response to the second bit signal, the transceiver
10
does not transmit the next data D
2
to the receiver
2
, and the previously transmitted source data D
1
is transmitted again.
In the conventional serial data transmission apparatus, only after the decoding, data separation, cyclic redundancy checking, and comparison processes are sequentially performed to determine that the data transmitted from the transceiver to the receiver is correct, the transceiver can transmit the next data to the receiver. Thus, the conventional serial data transmission apparatus has an inherent problem of lengthy transmission delay.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a serial data transmission apparatus that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
Another object of the present invention is to provide an improved serial data transmission apparatus which is capable of rapidly transmitting a large amount of data at a high speed by configuring a transceiver to have a function of performing an encoding operation before a cyclic redundancy checking operation is performed and by configuring a receiver to have a function of concurrently performing a decoding operation and a cyclic redundancy checking operation.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly
Chase Shelly A
De'cady Albert
Morgan & Lewis & Bockius, LLP
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