Echo canceler and echo path estimating method
First Claim
1. An echo canceler employed in a communication line network including a first transmission line for transmitting a voice of a four-wire side and a second transmission line for transmitting a voice of a second-wire side, said echo canceler comprising:
- training signal generator means for generating a training signal and supplying the same to said first transmission line;
coefficient calculator means for calculating a coefficient necessary for generating an echo replica based on a correlation established between the training signal supplied to said first transmission line and a signal of said second transmission line;
storage means for storing response characteristics of a plurality of hybrids;
selector means for selecting one of said response characteristics based on a relation between a transmission signal propagated from said four-wire side to said two-wire side and an echo signal propagated from said two-wire side to said four-wire side;
echo replica generator means for estimating an echo path by a predetermined learning algorithm and generating an echo replica by appropriately delaying the transmission signal and delaying the signal in accordance with a predetermined parameter; and
initial parameter setting means for setting an initial value of said parameter based on the response characteristic selected by said selector means.
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Accused Products
Abstract
The present invention relates to an echo canceler for training an echo path estimation without providing a hindrance to a speech. The echo canceler of the present invention includes a pseudo noise generator for generating a certain pseudo noise. This pseudo noise is forcibly supplied to a transmission line for transmitting a far-end talker'"'"'s voice. Here, in the case where the far-end talker'"'"'s transmitting speech level is faint or the far-end talker is in a speechless condition, a certain correlation is established between the pseudo noise and a signal of the transmission line for transmitting the near-end talker'"'"'s voice. Based on such a correlation as just mentioned, a coefficient for generating an echo replica is calculated. Therefore, a training for estimating an echo path is performed based on the pseudo noise and without depending on the far-end talker'"'"'s voice, thereby enabling to generate an appropriate echo replica.
47 Citations
14 Claims
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1. An echo canceler employed in a communication line network including a first transmission line for transmitting a voice of a four-wire side and a second transmission line for transmitting a voice of a second-wire side, said echo canceler comprising:
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training signal generator means for generating a training signal and supplying the same to said first transmission line; coefficient calculator means for calculating a coefficient necessary for generating an echo replica based on a correlation established between the training signal supplied to said first transmission line and a signal of said second transmission line; storage means for storing response characteristics of a plurality of hybrids; selector means for selecting one of said response characteristics based on a relation between a transmission signal propagated from said four-wire side to said two-wire side and an echo signal propagated from said two-wire side to said four-wire side; echo replica generator means for estimating an echo path by a predetermined learning algorithm and generating an echo replica by appropriately delaying the transmission signal and delaying the signal in accordance with a predetermined parameter; and initial parameter setting means for setting an initial value of said parameter based on the response characteristic selected by said selector means. - View Dependent Claims (2)
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3. An echo canceler employed in a communication line network for performing a transmission between a voice transmitted through a four-wire side and a voice transmitted through a two-wire side, said echo canceler comprising:
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storage means for storing response characteristics of a plurality of hybrids; selector means for selecting one of said response characteristics based on a relation between a transmission signal propagated from said four-wire side to said two-wire side and an echo signal propagated from said two-wire side to said four-wire side; echo replica generator means for estimating an echo path by a predetermined learning algorithm and generating an echo replica by appropriately delaying the transmission signal and transfiguring the signal in accordance with a predetermined parameter; and initial parameter setting means for setting an initial value of said parameter based on the response characteristic selected by said selector means.
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4. An echo path estimating method applicable to an echo canceler employed in a communication line network including a first transmission line for transmitting a voice of a four-wire side and a second transmission line for transmitting a voice of a second-wire side, said echo pass estimating method comprising:
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a training signal output step for generating a training signal and supplying the same to said first transmission line; a coefficient calculation step for calculating a coefficient necessary for generating an echo replica based on a correlation established between the training signal supplied to said first transmission line and a signal of said second transmission line; storing response characteristics of a plurality of hybrids; selecting one of said response characteristics based on a relation between a transmission signal propagated from said four-wire side to said two-wire side and an echo signal propagated from said two-wire side to said four-wire side; estimating an echo path by a predetermined learning algorithm and generating an echo replica by appropriately delaying the transmission signal and transfiguring the signal in accordance with a predetermined parameter; and setting an initial value of said parameter based on the response characteristic selected by said selector means.
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5. An echo path estimating method for estimating an echo path with respect to a communication line network for performing a transmission between a voice transmitted through a four-wire side and a voice transmitted through a two-wire side, said method comprising the steps of:
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storing response characteristics of a plurality of hybrids; selecting one of said response characteristics based on a relation between a transmission signal propagated from said four-wire side to said two-wire side and an echo signal propagated from said two-wire side to said four-wire side; estimating an echo path by a predetermined learning algorithm and generating an echo replica by appropriately delaying the transmission signal and transfiguring the signal in accordance with a predetermined parameter; and setting an initial value of said parameter based on the response characteristic selected by said selector means.
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6. An echo canceler employed in a communication line network including a first transmission line for transmitting a voice of a four-wire side and a second transmission line for transmitting a voice of a second-wire side, said echo canceler comprising:
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training signal generator means for generating a training signal and supplying the same to said first transmission line; coefficient calculator means for calculating a coefficient necessary for generating an echo replica based on a correlation established between the training signal supplied to said first transmission line and a signal of said second transmission line; storage means for storing frequency characteristics of a plurality of hybrids; selector means for selecting one of said frequency response characteristics based on a relation between a transmission signal propagated from said four-wire side to said two-wire side and an echo signal propagated from said two-wire side to said four-wire side; echo replica generator means for estimating an echo path by a predetermined learning algorithm and generating an echo replica by appropriately delaying the transmission signal and transfiguring the signal in accordance with a predetermined parameter; and initial parameter set means for setting an initial value of said parameter based on the frequency response characteristic selected by said selector means. - View Dependent Claims (7)
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8. An echo canceler employed in a communication line network for performing a transmission between a voice transmitted through a four-wire side and a voice transmitted through a two-wire side, said echo canceler comprising:
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storage means for storing frequency characteristics of a plurality of hybrids; selector means for selecting one of said frequency response characteristics based on a relation between a transmission signal propagated from said four-wire side to said two-wire side and an echo signal propagated from said two-wire side to said four-wire side; echo replica generator means for estimating an echo path by a predetermined learning algorithm and generating an echo replica by appropriately delaying the transmission signal and transfiguring the signal in accordance with a predetermined parameter; and initial parameter set means for setting an initial value of said parameter based on the frequency response characteristic selected by said selector means.
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9. An echo path estimating method applicable to an echo canceler employed in a communication line network including a first transmission line for transmitting a voice of a four-wire side and a second transmission line for transmitting a voice of a second-wire side, said echo pass estimating method comprising:
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a training signal output step for generating a training signal and supplying the same to said first transmission line; a coefficient calculation step for calculating a coefficient necessary for generating an echo replica based on a correlation established between the training signal supplied to said first transmission line and a signal of said second transmission line; storing frequency characteristics of a plurality of hybrids; selecting one of said frequency response characteristics based on a relation between a transmission signal propagated from said four-wire side to said two-wire side and an echo signal propagated from said two-wire side to said four-wire side; estimating an echo path by a predetermined learning algorithm and generating an echo replica by appropriately delaying the transmission signal and transfiguring the signal in accordance with a predetermined parameter; and setting an initial value of said parameter based on the frequency response characteristic selected by said selector means.
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10. An echo path estimating method for estimating an echo path with respect to a communication line network for performing a transmission between a voice transmitted through a four-wire side and a voice transmitted through a two-wire side, said method comprising the steps of:
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storing frequency response characteristics of a plurality of hybrids; selecting one of said frequency response characteristics based on a relation between a transmission signal propagated from said four-wire side to said two-wire side and an echo signal propagated from said two-wire side to said four-wire side; estimating an echo path by a predetermined learning algorithm and generating an echo replica by appropriately delaying the transmission signal and transfiguring the signal in accordance with a predetermined parameter; and setting an initial value of said parameter based on the frequency response characteristic selected by said selector means.
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11. An echo canceler employed in a communication line network including a first transmission line for transmitting a voice of a four-wire side and a second transmission line for transmitting a voice of a second-wire side, said echo canceler comprising:
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training signal generator means for generating a training signal and supplying the same to said first transmission line; coefficient calculator means for calculating a coefficient necessary for generating an echo replica based on a correlation established between the training signal supplied to said first transmission line and a signal of said second transmission line; first sampling means for up-sampling a first digital voice signal corresponding to the voice on said four-wire side; second sampling means for up-sampling a second digital voice signal corresponding to the voice on said two-wire side at a same sampling rate as said first sampling means; estimation means for estimating, on the basis of sampling results of the first and second up-sampler means, a response characteristic of a hybrid circuit for converting the four-wire side and the two-wire side; echo replica generator means for artificially generating an echo caused by said hybrid circuit by means of calculation using the estimated result and the sampled result by said sampling means; third sampling means for down-sampling an output signal of said echo replica generator means; and substraction means for subtracting an output signal of said third sampling means from said second digital voice signal. - View Dependent Claims (12, 13)
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14. An echo canceler employed in a communication line network for performing a transmission between a voice transmitted through a four-wire side and a voice transmitted through a two-wire side, said echo canceler comprising:
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first sampling means for up-sampling a first digital voice signal corresponding to the voice on said four-wire side; second sampling means for up-sampling a second digital voice signal corresponding to the voice on said two-wire side at a same sampling rate as said first sampling means; estimation means for estimating, on the basis of sampling results of the first and second up-sampler means, a response characteristic of a hybrid circuit for converting the four-wire side and the two-wire side; echo replica generator means for artificially generating an echo caused by said hybrid circuit by means of calculation using the estimated result and the sampled result by said sampling means; third sampling means for down-sampling an output signal of said echo replica generator means; and substraction means for subtracting an output signal of said third sampling means from said second digital voice signal.
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Specification