Patent ID: 8576114

Claim:
A radiolocation system for a vehicles moving along a guideway, comprising: an on-board transmitter for successively energizing radio frequency identification (RFID) transponders distributed along the guideway as the vehicle moves past each transponder, each transponder being associated with a transponder ID; an on-board radiofrequency identification (RFID) antenna; an on-board RFID detector/receiver configured to detect a coded RFID signal received by said RFID antenna containing the transponder ID from an energized transponder and to generate a lock signal upon detection of the coded RFID signal; at least one on-board crossover loop antenna configured to couple inductively with a guideway side crossover loop antenna co-located with each transponder as the vehicle moves past each transponder; an on-board phase demodulator for detecting a phase change in a signal from the at least one on-board crossover loop antenna when the at least one on-board crossover loop antenna is coupled with the guideway side crossover loop antenna; and an on-board computer configured, upon receipt of said lock signal, to determine the coarse position of the vehicle based on the transponder ID and to determine a precise position of the vehicle from a crossover point at which said phase change is detected.