MODELLING OF SAFETY-RELATED COMMUNICATIONS FOR RAILWAY APPLICATIONS

Abstract

Purpose. The authors according to requirements of the standard valid for safety-related communication between interlocking systems (EN 50159) analyze the situation of message undetected which is transmitted across BSC channel. The main part is orientated to description of model with CRC code used for messages assurance across noise communication channel. Methodology. For mathematical description of encoding, decoding, error detection and error correction is used algebra of polynomials. Findings. The determination of the intensity of dangerous failure caused by the electromagnetic interference was calculated. Originality. To obtain information on the probability of undetected error in transmission code and safety code and on the intensity of dangerous failure from the motel it was created program with graphical interface. To calculate the probability of undetected error for any block code (n, k) was created a supporting program that displays the probabilityof undetected error for selected interval of error bit rate. Practical value.From the measured and calculated values obtained by the simulation one can see that with increasing error bit rate is increasing also intensity of dangerous failures. Transmission code did not detect all corrupted messages therefore it is necessary to use safety code independent on transmission code in safety-related applications. CRC is not able to detect errors if all bits are logical 0.

Keywords

• safety integrity level
• railway applications
• safety-related communications
• safety code
• CRC
• Matlab
• modeling