Phase-controlled track circuit receiver

摘要

A track circuit receiver with a synchronous detector is provided wherein the phase of the reference voltage is caused to automatically follow that of the input voltage, so that there can be no reduction in output signal level as a result of phase differences between input voltage and reference voltage. Fail-safe operation is achieved by inverting the phase of the reference voltage and monitoring the rate of phase change at the output. The track circuit receiver of the present invention additionally utilizes simplified circuitry to achieve the foregoing.