Modeling of a continuous-type automatic locomotive signaling channel was conducted in the environment of MATLAB+Simulink on a simulation virtual test desk under stationary harmonic and random pulse noises. The size of the first interval between pulses in the “J” and “Z” code group was the parameter for the evaluation of signal-to-noise ratio influence on shape-time signal characteristics of the numerical code. Standard value of this interval is accepted within the limits of 120 to 180 milliseconds (ms). According to the results of modeling threshold value of signal-to-noise ratio was determined for the given carrier frequencies under the influence of stationary or random noise. Dependency graphs of the size of the first interval between pulses and threshold value of signal-to-noise ratio for the numerical code signal were designed by the obtained results. In order to verify the obtained results most probable intervals of threshold value of signal-to-noise ratio were calculated on the basis of experimental data. The data in question was received during automatic cab signaling systems operation at the mountain pass areas of the East Siberian Railway equipped with alternate-current electric traction. Calculation of sample characteristics of the general population of observations was conducted for carrier frequencies of 25 and 75 Hz under the influence of stationary harmonic and random pulse noises. Calculated threshold values of signal-to-noise ratio, obtained by the results of modeling, made it into most probable intervals of threshold values, obtained by the results of experimental observations, in all cases. Calculated threshold values of signal-to-noise ratio under the influence of random pulse noise were lower compared to those under the influence of stationary harmonic noise; the latter agrees with the classical concept of jamming resistance of radio engineering systems.
Automatic cab signaling, automatic cab signaling failure, statistical characteristics of signal-to-noise ratio, simulation virtual test desk, stationary and random noise of automatic cab signaling