Communication system doubles as a vehicle position transducer

The communication link between the wayside and vehicles in an Automated Guideway Transit (AGT) System is utilized to provide incremental position information. The guideway transmission line along with the vehicle antenna modulates (multiplies) the inductively coupled signals (data, voice, and identification) by a function which is related to the longitudinal position of each vehicle. The modulation is detected and processed on the wayside to simultaneously determine the position and velocity of each vehicle. The equations of the modulation and demodulation are discussed along with methods for processing the information. The development process of the guidway transmission line and electronics is presented. Typical performance parameters and characteristics are given.