Setting up a Phase Shift Overlay track circuit requires specialized equipment designed to generate, transmit, receive, and measure small changes in the phase of an AC signal.
The PSO transmitter generates a continuous AC signal at a specific stable frequency and power level. It may also include phase control and output impedance matching.
The PSO receiver detects small changes in the phase of the received AC signal compared with a reference signal. It may include phase comparators, filters, and processing circuitry to identify occupancy or broken rail conditions.
Tuned circuits or impedance matching units are placed at track block boundaries. They help define the electrical length of the track circuit and reduce signal reflections.
Transmission lines and cables connect the transmitter and receiver to the rails. Good cable quality helps reduce signal distortion and loss.
A phase meter or analyzer is used during setup and testing to measure the phase relationship between transmitted and received signals.
A calibrated shunt application device is used to simulate train occupancy and verify that the receiver responds at the proper detection threshold.