Adaptive echo canceling
First Claim
1. A method for transmitting data signals on a modem connection between a first and a second modem, comprising:
- determining echo cancellation coefficients for the first modem;
transmitting data signals in full duplex between the first and second modems;
providing a transmission hiatus of the second modem, in which an average energy of signals on a transmission line of the second modem is lower than in full duplex transmission;
identifying the transmission hiatus of the second modem by the first modem, by determining that the energy of the signals received by the first modem from the second modem is below a predetermined threshold energy;
beginning updating echo cancellation coefficients of the first modem, responsive to identifying the transmission hiatus of the second modem;
identifying further transmission hiatuses of the second modem by the first modem, by counting sampling periods, which sampling periods are a reciprocal of the sampling rate at which data signals are generated for transmission; and
periodically repeating the identifying of the transmission hiatus of the second modem by the first modem in order to recalibrate timing of the first modem,wherein providing the transmission hiatus comprises decreasing the number of symbols in a transmission window, from which signals are provided to the transmission line.
1 Assignment
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Accused Products
Abstract
A method for transmitting data signals in full duplex with echo cancellation between a first and a second modem connected by a two-wire channel, wherein a data signal is a function of at least one data symbol in a stream of data symbols generated by a modem comprising: determining echo cancellation coefficients for the first modem; transmitting data signals in full duplex between the two modems using the echo cancellation coefficients to cancel echoes in data signals received by the first modem; providing at least one hiatus in data symbol generation by the second modem while continuing data symbol generation by the first modem at a time at which echo cancellation using the echo cancellation coefficients is effective in canceling echoes in data signals received by the first modem; and updating the first modem echo cancellation coefficients during the at least one second modem hiatus.
25 Citations
34 Claims
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1. A method for transmitting data signals on a modem connection between a first and a second modem, comprising:
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determining echo cancellation coefficients for the first modem; transmitting data signals in full duplex between the first and second modems; providing a transmission hiatus of the second modem, in which an average energy of signals on a transmission line of the second modem is lower than in full duplex transmission; identifying the transmission hiatus of the second modem by the first modem, by determining that the energy of the signals received by the first modem from the second modem is below a predetermined threshold energy; beginning updating echo cancellation coefficients of the first modem, responsive to identifying the transmission hiatus of the second modem; identifying further transmission hiatuses of the second modem by the first modem, by counting sampling periods, which sampling periods are a reciprocal of the sampling rate at which data signals are generated for transmission; and periodically repeating the identifying of the transmission hiatus of the second modem by the first modem in order to recalibrate timing of the first modem, wherein providing the transmission hiatus comprises decreasing the number of symbols in a transmission window, from which signals are provided to the transmission line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A method for transmitting data signals on a modem connection between a first and a second modem, comprising:
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determining echo cancellation coefficients for the first modem; transmitting data signals in full duplex between the first and second modems; providing at least one transmission hiatus of the second-modem, in which an average energy of signals on a transmission line of the second modem is lower than in full duplex transmission; updating echo cancellation coefficients of the first modem during the second modem transmission hiatus; identifying an end of a transmission hiatus of the second modem by the first modem, by determining that the energy of the signals received by the first modem from the second modem is above a predetermined ending threshold energy; and ending the update of the echo cancellation coefficients responsive to identifying that the energy received by the first modem from the second modem is above the predetermined ending threshold energy, identifying at least some transmission hiatuses of the second modem by the first modem, by counting sampling periods, which sampling periods are a reciprocal of the sampling rate at which data signals are generated for transmission; and periodically repeating the identifying of the end of a transmission hiatus of the second modem by the first modem, wherein the second modem ends the transmission hiatus by increasing the number of symbols in a transmission window, from which signals are provided to the transmission line. - View Dependent Claims (33, 34)
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Specification