International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In coding theory, a linear code is an error-correcting code for which any linear combination of codewords is also a codeword. Linear codes are traditionally divided into block codes and convolutional codes. Linear codes allow more efficient encoding and decoding algorithms than other codes using the syndrome decoding. Linear codes are applied in methods for transmitting symbols on a communication channel so that, if errors occur in the communications, some errors can be corrected or detected by the recipient of a message block. The codewords in a linear block code are blocks of symbols that are encoded using more symbols than the original value to be sent. A (6, 3) linear block code example and its decoder implementation using Logisim, an educational tool for designing and simulating digital logic circuits, are given in the paper. The processes of encoding and decoding when detecting and correcting errors using this (6, 3) linear block code are illustrated. The material presented in the paper is used in the educational process in the University of Ruse.

In telecommunication, a convolutional code is a type of error-correcting code that generates parity symbols via the sliding application of a Boolean polynomial function to a data stream. A general convolutional encoder consists of a k*L-stage shift register and n modulo-2 adders, where L is the constraint length of the encoder. Convolutional codes are used to achieve reliable data transfer in numerous applications, such as digital video, radio, mobile communications and satellite communications. These codes are often implemented in concatenation with a hard-decision code, particularly Reed-Solomon codes. The material presented in the paper is used in the educational process in the University of Ruse. In order to better perception of the material active learning methods are applied. An individual assignment is given to each student and he/she has to solve the task during the practical exercise and present it at the end of the classes to the lecturer. The student should synthesize a convolutional encoder with NAND/XOR gates and flip-flops and to simulate its operation using Logisim, an educational tool for designing and simulating digital logic circuits.