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The QR code system was invented in 1994, at the Denso Wave automotive products company, in Japan. [5] [6] [7] The initial alternating-square design presented by the team of researchers, headed by Masahiro Hara, was influenced by the black counters and the white counters played on a Go board; [8] the pattern of position detection was found and determined by applying the least-used ratio (1:1:3 ...
The first element of a CIRC decoder is a relatively weak inner (32,28) Reed–Solomon code, shortened from a (255,251) code with 8-bit symbols. This code can correct up to 2 byte errors per 32-byte block. More importantly, it flags as erasures any uncorrectable blocks, i.e., blocks with more than 2 byte errors.
In Apple iOS 11, the native camera app can decode QR codes and can link to URLs, join wireless networks, or perform other operations depending on the QR Code contents. [30] Other paid and free apps are available with scanning capabilities for other symbologies or for earlier iOS versions. [31]
The BCH code with and higher has the generator polynomial. This code has minimal Hamming distance 15 and corrects 7 errors. It has 1 data bit and 14 checksum bits. It is also denoted as: (15, 1) BCH code. In fact, this code has only two codewords: 000000000000000 and 111111111111111 (a trivial repetition code ).
For a turbo code decoder, the front end would provide an integer measure of how far the internal voltage is from the given threshold. To decode the m + n -bit block of data, the decoder front-end creates a block of likelihood measures, with one likelihood measure for each bit in the data stream.
Luby transform code. In computer science, Luby transform codes ( LT codes) are the first class of practical fountain codes that are near-optimal erasure correcting codes. They were invented by Michael Luby in 1998 and published in 2002. [1] Like some other fountain codes, LT codes depend on sparse bipartite graphs to trade reception overhead ...
Raptor codes are formed by the concatenation of two codes. A fixed rate erasure code, usually with a fairly high rate, is applied as a 'pre-code' or 'outer code'.This pre-code may itself be a concatenation of multiple codes, for example in the code standardized by 3GPP a high density parity check code derived from the binary Gray sequence is concatenated with a simple regular low density ...
A Viterbi decoder uses the Viterbi algorithm for decoding a bitstream that has been encoded using a convolutional code or trellis code . There are other algorithms for decoding a convolutionally encoded stream (for example, the Fano algorithm ). The Viterbi algorithm is the most resource-consuming, but it does the maximum likelihood decoding.