Functioning of a quadrature receiver for automatic train signaling under frequency instability conditions and with a random phase of the signal carrier wave

Up to date, the task of increasing the fidelity of receiving the signals of continuous automatic train signaling (CATS) remains relevant. One of the possible ways to solve it is the correlation receiving of signals in the CATS receiving device. The article presents a correlation receiver with quadrature channels, as well as the results of a study of its operation under conditions of frequency instability and with a random carrier phase of the CATS signal. The study has shown that a change in the phase value of the carrier wave in the range of from 0° to 45° does not lead to a change in the amplitude of the envelope at the output of the quadrature correlator. It has also been found out that with an increase in the absolute frequency instability, carrying up to ±1 Hz relative to the nominal value of 25 Hz and 50 Hz, the amplitude of the envelope decreases by 0.41% and 0.44%, respectively. Thus, the correlation receiver with quadrature channels has at least a two-fold margin of stability for the absolute instability of the carrier frequency in comparison with the tolerance of±0.5 Hz according to the power supply standards of signaling devices relative to the nominal value of 25 (50) Hz. The loss of receiver performance is observed with absolute instability of the carrier frequency of ±9.3 Hz relative to the carrier frequency of 25 Hz and ±9.5 Hz relative to the carrier frequency of 50 Hz.