AF railway signalling circuit - has frequency converter near rails converting rail de-coupled voltage into higher frequency

摘要

The rail circuit is remote supplied and monitored in relation to unearthed transmission and receiver lines, screened against external voltages. The operation takes place between the track rails and a remote transceiver module. Near the rails (G1) is mounted a converter for the frequency (f1) of the voltage decoupled from the rails into a different frequency (f2), which is preferably higher. The receiver module (E) may be coupled to the reception lines (L3,L4) via a filter, tuned to the converter output frequency. The converter may be in the form of a full-wave rectifier (ZG). In the railway signalling and track monitoring high frequencies in the 10 kHz ranqe are used. In such instances, however, the transmit and receive ends must be earthed. The present system provides an AF circuit, excluding untimely free report over a track section also with an earth connection.