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Fence with localized intrusion detection

  • US 9,922,511 B2
  • Filed: 10/24/2011
  • Issued: 03/20/2018
  • Est. Priority Date: 10/29/2010
  • Status: Active Grant
First Claim
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1. A method for detecting and locating a cut in a detection cable having a plurality of detection means (Dn), preferably identical, and preferably with spacing between two adjacent detection means which is substantially equal,connection means at each of both ends thereof, each detection means preferably being a shock and/or vibration detector,and each detection means comprising two interfaces (121, 122), one on each side of the detection means,wherein each detection means (Dn), each of said interfaces (121, 122) has a transmission channel (201, 202) and a reception channel (211, 212) suitable for transmitting and receiving data to (or from) another detection means (Dn+1 or Dn−

  • 1) or to (or from) a management unit (UG) to which said detection means (Dn) is, in operation, directly connected, and in that each of said interfaces (121, 122) comprises at least three buffer memories (101, 105, 111;

    102, 106, 112) suitable for storing at least one byte of the signal frame, wherein;

    a first reception buffer memory (111, 112) for each interface (121, 122), wherein the byte or one of the bytes of the frame currently being received is stored;

    a second transmission buffer memory (101, 102) for each interface (121, 122), wherein the byte or one of the bytes of the frame currently being transmitted is stored;

    a third intermediate buffer memory (105, 106) for each interface (121, 122) which acts as a link between the reception channel (211, 212) on one side and the transmission channel (202, 201) on the other side;

    wherein, the method comprises the steps;

    the management unit (UG) periodically transmits a query in the form of at least one byte frame (referred to as a “

    query frame”

    ) to the detection means to which it is directly connected;

    each detection means (Dn) transmits this query frame to the next adjacent unit, which may be either another detection means (Dn+1) or a management unit (UG), or a terminal unit;

    in response to the query, the management unit (UG) expects to receive the same query frame as that transmitted and comprising the sequential number of the last detection means belonging to the detection cable connected to the management unit (UG),the reception of said at least one query frame by said next adjacent unit of said detection means (Dn) triggers the transmission of an acknowledgement frame to the sender;

    if the detection means (Dn) has not received the acknowledgement frame from the next adjacent unit (Dn+1) thereof, said detection means (Dn) transmits the query frame received to the preceding adjacent unit (Dn−

    1) and the management unit (UG) finally receives the same query frame as that transmitted, but observes that the sequential number of said query frame is in this case (Dn) and not the sequential number of the last detection means of the cable;

    the management unit UG then decides that the cable is cut between the detection means (Dn) and the detection means (Dn+1).

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