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Method for measuring a signal transmission delay time, central station, terminal station and network to perform this method

  • US 5,808,766 A
  • Filed: 09/20/1996
  • Issued: 09/15/1998
  • Est. Priority Date: 09/22/1995
  • Status: Expired due to Fees
First Claim
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1. An optical network with a plurality of terminal stations TS1-TSn connected to a central station (CS) via a tree-like connection structure, and wherein said terminal stations are adapted to send cells containing information signals to said central station in dedicated time slots, said central station including means to receive a predetermined ranging signal from one terminal station (TSi) of said plurality of terminal stations in an idle time window during which no said cells are transmitted, said ranging signal initially having a length or duration equal to two times a maximum possible difference, among respective terminal stations, in respective transmission delays between each terminal station and said central station, and said terminal stations each including means to send said predetermined ranging signal, characterized in that said central station additionally includes:

  • means to send a start signal (start CR) from said central station to said terminal stations;

    means to send, after a first predetermined time interval after the sending of said start signal, an inhibit signal from said central station to said terminal stations, to indicate to said terminal stations that no said cells are to be transmitted during said idle time window;

    error recovery means to interpret error codes included in said cells by said terminal stations and to recover said information signals in case of corruption of said information signals due to the transmission of said predetermined ranging signal outside said idle time window;

    means to determine a signal transmission delay time, between said one terminal station and said central station, from the contents of said ranging signal received by said central station from said one terminal station during said idle time window; and

    wherein said terminal stations each additionally include;

    means to receive said start signal from said central station sent to said terminal stations and to send out said predetermined ranging signal, a second predetermined time interval after the receipt of said start signal, said predetermined ranging signal having an amplitude relatively near to amplitude of said information signals; and

    means to include said error codes in said cells.

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