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COMMUNICATION APPARATUS AND DELAY DETECTING METHOD

  • US 20130170388A1
  • Filed: 09/15/2010
  • Published: 07/04/2013
  • Est. Priority Date: 09/15/2010
  • Status: Active Grant
First Claim
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1. A communication apparatus that performs periodical communication with another communication apparatus connected via a transmission line, the communication apparatus comprising:

  • a clock configured to measure time;

    a communicating unit configured to transmit and receive a communication frame;

    a time-stamp generating unit configured to generate a time stamp using the clock during transmission or during reception of the communication frame transmitted and received by the own communication apparatus;

    a transmission-data storing unit configured to store periodical transmission data stored in the periodically-transmitted communication frame;

    a reception-data storing unit configured to store the periodical transmission data in the periodically-received communication frame;

    a frame processing unit configured to generate a refresh instruction frame including a data refresh instruction to the other communication apparatus, the periodical transmission data in the transmission-data storing unit, and a frame transmission time, which is a time stamp of transmission timing, acquired from the time-stamp generating unit and store, upon receiving a refresh instruction frame from the other communication apparatus, periodical transmission data included in the refresh instruction frame in the reception-data storing unit; and

    a one-way-delay detecting unit configured to determine, upon receiving the refresh instruction frame, whether a next refresh instruction frame is received within a first delay allowable time after the refresh instruction frame is received last time and determine, when the next refresh instruction frame is received within the first delay allowable time, according to whether a transmission time of the refresh instruction frame from the other communication apparatus to the own apparatus is within a second delay allowable time, whether a delay has occurred in a communication frame transmitted from the other communication apparatus.

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