Bezpečnostní kódy v železničních zabezpečovacích zařízeních
Aggregation/disaggregation method for safety models
The paper concerns the possibilities for mathematical modelling of safety related systems (equipment oriented on safety). Some mathematical models have been required by the present European Standards for the railway transport. We are interested in the possibility of using Markov’s models to meet these Standards. In the text an example of using that method in the interlocking equipment life cycle is given. An efficient aggregation/disaggregation method for computing some characteristics of Markov...
Message doubling and error detection in the binary symmetrical channel
The error correcting codes are a common tool to ensure safety in various safety-related systems. The usual technique, employed in the past, is to use two independent transmission systems and to send the safety relevant message two times. This article focuses on analysis of the detection properties of this strategy in the binary symmetrical channel (BSC) model. Besides, various modifications of the mentioned technique can be used. Their impact on the detection properties can be significant, positively...
Detection codes in railway interlocking systems
This paper describes a model of influence of random errors on the safety of the communication. The role of the communication in railway safety is specified. To ensure a safe communication, using of safety code is important. The most important parameter of the safety code is the maximal value of the probability of undetected error. Problems related with computing of this value are outlined in the article. As a model for the information transmission the binary symmetrical channel is introduced. ...
Calculation of the detection properties in the binary symmetrical channel
One of the important parts of railway signalling systems design is the safety of communication, achievable - among others - with the error detecting code. Getting evidence of quantitative safety targets, especially the probability of undetected error of the code, is a surprisingly complicated issue. We've analysed 2048 irreducible self-adjoint generator polynomials of the degree 32. More than 70 of these have a maximum probability of failure lower than the standard codes generally used. In this...
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