Excavating
Patent
1997-01-29
1999-05-11
Chung, Phung M.
Excavating
371 491, 371 30, G06F11/10
Patent
active
059035811
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method of detecting transmission errors that may occur during serial transmission of digital signals and correcting the detected transmission errors.
BACKGROUND ART
Binary digital signals transmitted through a transmission line suffer bit reversal at a certain rate that depends upon the characteristics of the transmission line.
In order to detect and correct transmission errors due to bit reversal, redundant characters or check bits are added to information bits that represent information to be transmitted.
A hamming code V shown in FIG. 38 has its respective characters spaced a predetermined distance not less than three (hamming distance) from adjacent ones. If there is an error in one bit or character, such an error can be easily detected because in such a case, the hamming distance between the bit in error and the original bit changes from zero to one and the hamming distance between the bit in error and any adjacent bit changes from three to two.
Specifically, in the transmitter (see FIG. 38A), data a.sub.k (k=1, 2 . . . ) and redundant bits c.sub.1 (1=1, 2 . . . ) are mixed together using a coding matrix B to create e.g. a hamming code "c.sub.1 c.sub.2 a.sub.1 c.sub.3 a.sub.2 a.sub.3 ".
Upon receiving the hamming code, the receiver checks it by multiplying the code by a check matrix M as shown in FIG. 38B. operations will be (100) as shown in FIG. 38C. Thus, it is possible to detect and specify the bit in error. FIG. 38D show the results of operations on bits in error.
One problem with such a hamming code is that such a code needs a relatively large number of redundant bits c.sub.k (in the above example, the ratio of information bits to the entire transmission bits is 4/7=57.2%), and thus the transmission efficiency is low. Also, in this arrangement, only one error can be detected and corrected at one time. That is, if errors occur in two bits, it is impossible to detect and correct such errors.
Now therefore, it is a first object of this invention to provide a method for detecting multiple transmission errors with high reliability while maintaining high transmission efficiency. A second object of the invention is to provide a method for correcting multiple transmission errors with high reliability while maintaining high transmission efficiency.
DISCLOSURE OF THE INVENTION
In order achieve the first object, there is provided, according to this invention, a method for detecting errors in transmission of n (in number) digital signals which are a mixture of k (in number) information bits (a.sub.k) and n-k check bits (c.sub.(n-k)), the method comprising, in a processing unit of a transmitter: system having integer q as its base (n =q.sup.h) to the respective n digital signals, allocating the check bits (c.sub.(n-k)) to respective addresses (ad) each including h-r (1.ltoreq.r.ltoreq.h) integers q-1 or 0's, and allocating the information bits (a.sub.k) to the remaining ones of the addresses, selecting h-r digits from the h digits of each of the addresses (ad) without duplication, creating .sub.h C.sub.h-r .multidot.q.sup.h-r bit strings (g) each comprising q.sup.r bits having the same integers for the selected h-r digits, determining the value of the check bits (c.sub.(n-k)) in each bit string (g) to which the largest address (ad) is attached by subjecting the respective bit strings (g) to parity checks, thus producing a transmission code (1), and in a processing unit of a receiver: attaching n addresses (ad) which are h-digit numbers expressed in a number system having integer q as its base (n =q.sup.h) to the respective n digital signals of the transmission code (1) received from the transmitter, selecting h-r digits from the h digits of each of the addresses (ad) without duplication, creating .sub.h C.sub.h-r .multidot.q.sup.h-r bit strings (g) each comprising q.sup.r bits having the same integers for the selected h-r digits, and detecting errors in transmission by subjecting the respective bit strings (g) to parity checks.
In this method, in the transmi
REFERENCES:
patent: 5740186 (1998-04-01), Widmer
LandOfFree
Method of detecting and correcting transmission error of digital does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of detecting and correcting transmission error of digital, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of detecting and correcting transmission error of digital will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-251599