Echo canceling method and apparatus for data over cellular
DCFirst Claim
Patent Images
1. Data communications equipment apparatus comprising:
- an echo canceler for processing an echo-corrupted signal to provide an echo-canceled signal, wherein the echo canceler has a set of tap coefficients, each tap coefficient having an initial value determined during a half-duplex portion of a training sequence;
circuitry for detecting the presence of a residual echo signal in the echo-canceled signal during full-duplex transmission that is subsequent to said half-duplex portion of the training sequence; and
a processor, coupled to the circuitry, for adjusting each initial value of each tap coefficient by a fixed amount when the detected residual echo signal during full-duplex transmission is greater than a predetermined amount.
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Abstract
A processor of a cellular modem monitors for the presence of a residual echo signal during a full-duplex portion of a training sequence. In particular, the processor monitors an equalizer error signal during a full-duplex training phase that follows the half-duplex training phase for the echo canceler. If the processor detects a level of the error signal greater than a predefined threshold, the processor presumes the increase in the error signal is due to the presence of a residual echo signal and performs a predefined adjustment of the taps of the corresponding echo canceler of the cellular modem.
79 Citations
25 Claims
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1. Data communications equipment apparatus comprising:
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an echo canceler for processing an echo-corrupted signal to provide an echo-canceled signal, wherein the echo canceler has a set of tap coefficients, each tap coefficient having an initial value determined during a half-duplex portion of a training sequence; circuitry for detecting the presence of a residual echo signal in the echo-canceled signal during full-duplex transmission that is subsequent to said half-duplex portion of the training sequence; and a processor, coupled to the circuitry, for adjusting each initial value of each tap coefficient by a fixed amount when the detected residual echo signal during full-duplex transmission is greater than a predetermined amount. - View Dependent Claims (2, 3, 4, 5)
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6. Data communications equipment apparatus comprising:
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an echo canceler for processing an echo-corrupted signal to provide an echo-canceled signal, wherein the echo canceler has a set of tap coefficients, each tap coefficient having an initial value; circuitry for detecting the presence of a residual echo signal in the echo-canceled signal; and a processor, coupled to the circuitry, for adjusting each initial value of each tap coefficient by a fixed amount when the detected residual echo signal is greater than a predetermined amount during a full-duplex training phase that occurs subsequent to a half-duplex training phase. - View Dependent Claims (7, 8, 9, 10, 11)
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12. An improved data communications equipment apparatus for receiving a data signal, the apparatus including an echo canceler for processing an echo-corrupted signal to provide an echo-canceled signal, the echo canceler having a set of tap coefficients, each tap coefficient having an initial value, wherein the improvement comprises:
a processor for adjusting each initial value of each tap coefficient by a fixed amount during full-duplex communication which occurs subsequent to a half-duplex training phase for reducing a residual echo signal component of the echo-canceled signal. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method for reducing a residual echo signal in data communications equipment apparatus, the data communications equipment comprising an echo cancelor, the method comprising the steps of:
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a) performing a half-duplex training sequence with a far-end data communications equipment apparatus to determine an initial value for each one of a set of tap coefficients of the echo cancelor; b) subsequent to the half-duplex training sequence, performing full-duplex transmission with the far-end data communications equipment; d) during the subsequent full-duplex transmission, estimating a value of the residual echo signal; and e) adjusting the initial value of each one of the set of tap coefficients of the echo canceler by a fixed amount only if the estimated value of the residual echo signal is greater than a predetermined amount. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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Specification