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Modem line probing signal techniques

  • US 5,515,398 A
  • Filed: 03/15/1994
  • Issued: 05/07/1996
  • Est. Priority Date: 03/15/1994
  • Status: Expired due to Term
First Claim
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1. A modem, associated with a computer, for generating a line probing signal over a communication channel for use by a receiving modem to determine the non-linearity of the electrical characteristics of said communication channel comprising, in combination:

  • a first bus for communicating with said computer;

    a transmitter for generating a finite plurality of different tones, said tones having a predetermined relative phase relationship; and

    a second bus for delivering signals, including said tones, to said communication channel,said tones being divided into a first group having a first predetermined phase and a second group having a second predetermined phase, said first and second predetermined phases having a predetermined phase relationship, said predetermined phase relationship arranged to substantially minimize the peak to root mean square average value of said line probing signal;

    wherein said transmitter comprises a signal generator for generating said line probing signal at a first power level for a first predetermined time period and for generating said line probing signal at a second power level for a second predetermined time period later than said first predetermined time period;

    said line probing signal at said first power level comprising tones having a plurality of amplitude peaks at a power level above the average signal power level of a nominal transmission data signal so as to attain peak amplitudes in the non-linear region of said communication channel.

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