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Method of determining automatically the rate of data signals in a modem

  • US 4,663,766 A
  • Filed: 10/10/1984
  • Issued: 05/05/1987
  • Est. Priority Date: 10/10/1984
  • Status: Expired due to Term
First Claim
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1. In a data communication system having first and second modems for exchanging data signals at one of a first and a second rate, a method of determining the rate of the signals sent by the first modem comprising:

  • a. transmitting a sequence of training signals, said training signals being sent only for the purpose of determining the rate of the signals being sent by the first modem and containing no message data interspersed therein from said first modem said sequence comprising a first segment comprising a series of preselected signals;

    b. detecting said sequence of training signals at said second modem;

    c. initializing a pulse generator which outputs pulses which correspond to the period of training signals having a first data rate;

    d. initializing a timing means which operates form the moment said sequence is first detected for a first pre-selected time period which corresponds to the period of said first segment at said first data rate;

    e. comparing the training signals received after said first segment with a set of stored constants representation of the first data rate to determine whether they correspond to the pre-selected signals of said second segment; and

    f. changing said pulse generator to generate pulses corresponding to the second rate if said received signals do not correspond to said stored constants.

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