Transceiver circuit including an echo canceller
AssigneeSTMicroelectronics S.r.l.
InventorWilliam Glass
Life of this patent
Estimating the term…
Abstract
A circuit for transmitting and receiving communications. The circuit includes a transmit block, a receive block, and an echo canceller, coupled to the transmit block and to the receive block, for determining an echo signal and subtracting it from the received signal, the determination of the echo signal involving a predetermined number N of coefficients calculated at the beginning of each of the communications in an initialization phase. The circuit periodically updates during communication a restricted group of coefficients chosen from among the most significant coefficients. The present invention also relates to an echo cancellation method.
Claims31
A circuit for transmitting and receiving communications, including:
- a transmit block,
- a receive block,
- an echo canceller, coupled to the transmit block and to the receive block, for determining an echo signal and subtracting it from the received signal during communication, the determination of the echo signal involving a predetermined number of coefficients calculated at a beginning of the communication in an initialization phase, and
- means for periodically updating, during the communication, a restricted group of coefficients chosen from among the most significant coefficients,
- wherein said restricted group includes a maximum coefficient obtained at an end of the initialization phase and a defined number of its neighboring coefficients.
A method of echo canceling in a circuit adapted for transmitting and/or receiving a respectively transmitted and/or received signal, and in which a signal representative of the echo is subtracted from the received signal during communication, the signal representative of the echo being determined by summing up N terms, each term being obtained by multiplying a sample of rank i of the transmitted signal by a coefficient of rank i, i ranging between 1 and N,
- including the steps of:
- in an initialization phase corresponding to a beginning of a communication, determining a value of the N coefficients of rank i,
- determining the most significant coefficients, and
- during the communication, updating coefficients of a restricted group of said coefficients chosen from among the most significant coefficients, said restricted group including a maximum coefficient obtained at an end of the initialization phase and a defined number of its neighboring coefficients.
A method of generating an estimated echo signal to correct for echoes in a received signal of a communication, the method comprising acts of:
- determining values of N coefficients during an initialization phase, the N coefficients providing weights to samples of a transmitted signal to form a basis of the estimated echo signal the estimated echo signal being used to modify the received signal during the communication;
- and
- updating values of a restricted group of the N coefficients during the communication by selecting the restricted group of the N coefficients based on a coefficient having a greatest value after the initialization phase.
An echo canceller comprising:
- a first group of coefficients configured to weight samples of a transmission signal to provide a basis for an estimated echo signal, the estimated echo signal being used to modify, when present, a received signal during a communication;
- and
- means for adjusting values of an active group of the first group of coefficients,
- wherein, during an initialization phase, the active group includes the first group and, during a communication phase, the active group includes only a restricted group of coefficients selected from the first group including a maximum coefficient in the first group having a greatest value at an end of the initialization phase.
The echo canceller of claim 19, wherein the active group in the communication phase includes only coefficients in the first group having a value within a predetermined percentage of the maximum coefficient.
The echo canceller of claim 21, wherein the means for adjusting the active group includes means for subtracting the estimated echo signal from a received signal to provide an error signal.
Dependencies are inferred from the claim text.