Location of a transponder center point

• US 8,576,114 B2
• Filed: 06/24/2011
• Issued: 11/05/2013
• Est. Priority Date: 06/24/2011
• Status: Expired due to Fees

• Current Assignee: Thales Canada Incorporated (Thales SA)
• Original Assignee: Thales Canada Incorporated (Thales SA)
• Inventors: Kanner, Abe, Seitz, Pat
• Primary Examiner(s): Sotomayor, John B
• Application Number:
  US13/168,519
• Publication Number:
  US 20120326916A1
• Time in Patent Office: 865 Days
• Field of Search: 342 42- 51
• US Class Current: 342/42
• CPC Class Codes: B61L 2027/204 using Communication-based Train Control [CBTC]
• CPC Class Codes: B61L 25/025 Absolute localisation, e.g. providing geodetic coordinates
• CPC Class Codes: B61L 3/121 using magnetic induction
• CPC Class Codes: B61L 3/125 using short-range radio transmission
• CPC Class Codes: G01S 1/14 using amplitude comparison of signals transmitted simultaneously from antennas or antenna systems having differently oriented overlapping directivity-characteristics
• CPC Class Codes: G01S 13/82 wherein continuous-type signals are transmitted
• CPC Class Codes: G01S 13/84 for distance determination by phase measurement

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.

Claims

1. 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.

2. A radiolocation system as claimed in claim 1, wherein a said on-board crossover loop antenna is located on each side of said on-board RFID antenna.

3. A radiolocation system as claimed in claim 1, further comprising an on-board look-up table containing the course positions of the trackside transponders based on transponder ID, and wherein said on-board computer is configured to determine the coarse position of the vehicle by looking up the transponder ID in said look-up table.

4. 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.

5. A method as claimed in claim 4 wherein a lock signal is generated in response to the receipt of the coded identification signal, and an on-board computer on the moving vehicle determines the crossover point upon receipt of the lock signal.

6. A method as claimed in claim 5, wherein the moving vehicle receives the second signal at two crossover loop antennas, one on each side of an antenna receiving the coded radio frequency identification signal.

7. A transponder as claimed in claim 4 further comprising a signal conditioner for conditioning the signal for the crossover loop antenna.

8. 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.

9. A method as claimed in claim 8, wherein the coarse position of the vehicle is determined by looking up the transponder ID in an on-board look-up table.