Fault tolerant apparatus for detecting the passage of a moving body

• US 5,889,478 A
• Filed: 03/31/1997
• Issued: 03/30/1999
• Est. Priority Date: 04/01/1996
• Status: Expired due to Term

• Current Assignee: Matra Transport International (Siemens AG)
• Original Assignee: Matra Transport International (Siemens AG)
• Inventors: Minesi, Didier
• Primary Examiner(s): Hofsass, Jeffery A.
• Assistant Examiner(s): MANNAVA, ASHOK K
• Application Number:
  US08/829,661
• Time in Patent Office: 729 Days
• Field of Search: 340/933, 340/936, 340/941, 340/825.54, 340/572, 340/573, 340/552, 340/553, 340/561, 340/445, 340/447, 340/448, 340/572.5
• US Class Current: 340/933
• CPC Class Codes: B61L 25/043 using inductive tags
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles

Abstract

On the moving body, the apparatus comprises an active transponder, and on the track it comprises a passive responder. The transponder has an LF transmitter and an MF transmitter which, during displacement of the moving body, transmit to a zone through which the responder passes during said displacement. The responder has an LF receiver circuit and an MF receiver circuit having tuned radiating circuits that are associated so that an LF signal induced in the LF circuit causes the MF radiating circuit of the responder to be closed at the LF rate. The transponder responds to disturbances in the MF transmitter caused by the MF circuit of the responder being closed. The MF circuit of the responder includes two units having respective tuned radiating circuits that are strongly coupled together. Each is connected to a respective logic unit which, when excited, delivers a digital message causing the MF radiating circuit to be closed only for bits of a determined value in the digital message.

Claims

1. Apparatus for detecting the passage of a moving body at a determined point in its guided displacement along a track, the apparatus comprising, on the moving body, an active interrogation assembly connectable to an electrical power supply, and on the track, a passive responder, wherein:

the interrogation assembly has a low frequency transmitter and a medium frequency transmitter that continuously operates while the moving body is moving, each having a respective antenna directed to transmit towards a predetermined zone with respect to the moving body and selected to be traversed by the responder during displacement of the moving body; and

the responder comprises a low frequency signal receiver circuit and a medium frequency signal receiver circuit having respective tuned radiating circuits associated in such a manner that a low frequency signal induced in the low frequency circuit by passage through the zone causes the medium frequency radiating circuit of the responder to be closed at the rate of the low frequency, with the interrogation assembly also having means responsive to disturbances in the medium frequency transmitter caused by closing the medium frequency tuned radiating circuit of the responder when the responder is in said zone;

wherein said medium frequency circuit of the responder includes at least two assemblies having respective tuned radiating circuits that are strongly coupled together and each connected to a respective one or two logic units that arranged to deliver a digital message and causes the medium frequency radiating circuit to be closed only for bits of a determined value in the digital message, the digital messages originating from one of the logic unit being different from the digital message originating from the other and being transmitted asynchronously; and

said low frequency signal receiver circuit includes a plurality of tuned radiating circuits connected in series that are spaced apart in the displacement direction of the moving body and that are provided with means for closing them simultaneously at the rate of the message originating from the associated logic unit.

2. Apparatus according to claim 1, wherein each of said logic units includes a programmable read-only memory and a sequencer energized by said low frequency receiver circuit and designed to cause delivery of the messages by the two logic units asynchronously.

3. Apparatus according to claim 2, wherein said sequencers are constructed to transmit said messages repetitively at intervals that are separated by a determined number of periods of a clock derived from the low frequency signal, the number of periods between two messages originating from one of the logic units and the number of periods between the messages originating from the second unit having no common divider which is an interrogator.

4. Apparatus according to claim 1, wherein the closure means are diodes connected in series in a common current loop also including a current generator and switch means.

5. Apparatus for detecting the passage of a moving body at a determined point in its guided displacement along a track, the apparatus comprising, on the moving body, an active interrogation assembly connectable to an electrical power supply, and, on the track, a passive responder, wherein:

the active interrogation assembly has a low frequency transmitter and a medium frequency transmitter for continuous operation while the moving body is moving, each having a respective antenna directed to transmit towards a zone which is predetermined with respect to the moving body and selected to be traversed by the responder during displacement of the moving body; and

the responder comprises;

a low frequency signal receiver circuit having a circuit tuned at the low frequency, and

a medium frequency receiving circuit including two assemblies having respective radiating circuits tuned at the medium frequency and strongly electromagnetically mutually coupled, each of said assemblies having a respective one of two logic units that are each arranged to deliver a respective digital message when energized and to cause the respective medium frequency radiating circuit to be closed only for bits of a determined value in the respective digital message, the digital message originating from one of the logic units being different from the digital message originating from the other of the logic units and being transmitted asynchronously therewith,

wherein said low frequency signal receiver circuit is associated with said medium frequency receiving circuit and responsive to a low frequency signal induced in the low frequency receiver circuit by passage through the zone to cause each of the two logic circuits of the medium frequency receiving circuit to close the respective medium frequency radiating circuit, at the rate of the low frequency, and

wherein the interrogation assembly has means responsive to closure of one of the medium frequency tuned radiating circuits of the responder when the responder is in said zone to identify said digital messages.

6. Apparatus according to claim 5, wherein the low frequency signal receiver circuit includes a plurality of tuned radiating circuits connected in series that are spaced apart in the displacement direction of the moving body and that are provided with means for closing them simultaneously at the rate of the message originating from the associated unit.

7. Apparatus according to claim 6, wherein the closure means are diodes connected in series in a common current loop also including a current generator and switch means.

8. Apparatus according to claim 5, wherein each of said logic units includes a programmable read-only memory and a sequencer energized by said low frequency receiver circuit and designed to cause delivery of the messages by the two logic units asynchronously.

9. Apparatus according to claim 8, wherein said sequencers are constructed to transmit said messages repetitively at intervals that are separated by a determined number of periods of a clock derived from the low frequency signal, the number of periods between two messages originating from one of the logic units and the number of periods between the messages originating from the second unit having no common divider which is an interrogator.