Location of a transponder center point
AssigneeThales Canada Inc.
InventorsAbe Kanner, Pat Seitz
Life of this patent
Estimating the term…
Abstract
In a radio location system for vehicles moving along a guideway, a transmitter for energizes a transponder beside the guideway. A first detector for detects a response signal from the energized transponder to determine the transponder identification. A second detector detects a positional signal received from the transponder that is decoupled from the first signal and contains precise positional information. In one embodiment, the second detector picks up a crossover signal from a crossover antenna.
Claims9
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.
A transponder for use with a radiolocation system for a vehicles moving along a guideway, comprising:
- a radiofrequency identification (RFID) transponder antenna;
- a crossover loop antenna for inductively coupling with a crossover loop antenna on a passing moving vehicle;
- an RFID receiver/transmitter responsive to reception of an energizing signal from a moving vehicle to transmit a coded RFID signal containing a transponder ID through said RFID antenna;
- a receiver/rectifier for generating power from the energizing signal;
- and
- an oscillator powered by the receiver/rectifier for generating a signal for the crossover loop antenna upon receipt of said energizing signal.
A method of determining the position of a moving vehicle on a guideway with precision, comprising:
- transmitting a radio frequency identification (RFID) energizing signal to a trackside RFID transponder from the moving vehicle;
- receiving a coded identification first signal containing a transponder ID from the guideway side transponder;
- receiving at a crossover loop antenna a second signal from guideway side crossover loop antenna co-located with the guideway side transponder;
- determining a coarse position of the vehicle from the transponder ID;
- detecting a phase change in the second signal;
- and
- determining the precise position of the moving vehicle from a crossover point at which the phase change is detected.
Dependencies are inferred from the claim text.