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System for, and method of, transmitting and receiving through telephone lines signals representing data

  • US 5,627,885 A
  • Filed: 02/14/1994
  • Issued: 05/06/1997
  • Est. Priority Date: 02/14/1994
  • Status: Expired due to Term
First Claim
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1. In combination for transmitting from a transmitter and receiving at a receiver through telephone lines data represented by successive digital signals indicating analog levels in a plurality as increments of data,first means for modulating the successive digital signals with digital signals in a pseudo random code,second means responsive to the digital signals from the first means for converting such digital signals to corresponding analog signals and for introducing the analog signals into the telephone lines for transmission through the telephone lines,third means responsive to the analog signals passing through the telephone lines for converting such analog signals to corresponding digital signals,a linear echo canceller having a first plurality of adjustable coefficients,fourth means, including the linear echo canceller, responsive to the digital signals from the third means and the digital signals in the pseudo random code, adjusted in accordance with the adjustable coefficients in the first plurality, for comparing such digital signals to cancel the digital signals transmitted from the receiver to the transmitter and reflected from the transmitter back to the receiver to obtain resultant digital signals and for adjusting the coefficients in the first plurality in the linear echo canceller in accordance with the results of such comparison,a non-linear echo canceller having a second plurality of adjustable coefficients,fifth means, including the non-linear echo canceller, responsive to the resultant digital signals from the fourth means and the digital signals in the pseudo random code, adjusted in accordance with the adjustable coefficients in the second plurality, for comparing such digital signals to provide an enhanced approximation of the digital signals representing the data and for adjusting the coefficients in the second plurality in accordance with the results of such comparison, andsixth means responsive to the digital signals from the fifth means for processing such digital signals to recover the digital signals representing the data.

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