Transient Behaviour of a Data Transmission System using FSK-modulation and Coupled Inductive Loops

Safety and efficiency of modern transportation systems require the intensive use of data transmission devices. They should operate in both directions between on-board and wayside equipment. Especially, high-speed applications require a suitable data transmission rate. The design of the entire transmission path has to consider the input and output signals of all the involved components, investigated here for the modulation method FSK. It is demonstrated how the transient behaviour can be simulated using SPICE subcircuits. The main components to be modelled are the following: modulator, a fixed and a movable inductive loop, connected to an input and an output filter, amplifier and limiter, and demodulator.