Technique for reducing echoes in conference communications
First Claim
1. Apparatus for providing conferencing communications comprisingmeans for forming a signal sum equal to a sum of signals received from at least three information signal sources along with an echo compensation signal, the signal received from each information source including echoes and said signal sum including an aggregation of such echoes;
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Abstract
Distortion and instability due to echoes in conference communications is reduced through the use of an echo estimating filter disposed in a conference bridging circuit. This circuit includes a signal combiner which receives information signals from each of the parties in the conference communications and provides an output signal which is a combination of the received information signals and an echo compensation signal. The echo estimating filter provides this echo compensation signal in response to the combiner output signal. Advantageously, the echo estimating filter can be fixed or adaptive. In the latter case, the adaptation can be in response to the received information signals or to training sequences.
34 Citations
13 Claims
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1. Apparatus for providing conferencing communications comprising
means for forming a signal sum equal to a sum of signals received from at least three information signal sources along with an echo compensation signal, the signal received from each information source including echoes and said signal sum including an aggregation of such echoes; - and
an echo estimating filter having an input and an output, said input being solely responsive to said signal sum and said output being only coupled to said forming means, said filter forming said echo compensation signal which is an estimate of said aggregation of echoes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of reducing echoes in conferencing communications comprising the steps of
forming a signal sum equal to a sum of signals received from at least three information signal sources along with an echo compensation signal, the signal received from each information signal source including echoes and said signal sum including an aggregation of such echoes, and forming said echo compensation signal using a filter whose input is solely responsive to said signal sum and whose output is only used in said forming step.
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13. Apparatus for providing conferencing capabilities for a at least three conferees, each conferee capable of transmitting information via a transmit link and receiving information via a receive link, said apparatus comprising
means for summing signals on said transmit link for each conferee along with an echo compensation signal to provide a signal sum which is coupled to each receive link; -
a filter for generating said echo compensation signal in response to said signal sum; and a subtracter associated with each conferee for subtracting the signal on each said transmit link from said signal sum.
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Specification