Speech additive distribution equipment for conferencing system
First Claim
1. An audio bridge for a conferencing system, comprising:
- channel signal processing means comprising at least three channel signal processing circuits, each of said channel signal processing circuits including, respectively, a receiving side for receiving a channel signal, a transmitting side for transmitting a channel signal, an echo canceller for cancelling an echo signal fed back to said receiving side from said transmitting side, means for adjusting levels of an output of said echo canceller and a transmitting signal transmitted through the transmitting side of said channel signal processing circuit, ERL determining means for determining an echo rejection level on the basis of said output from said echo canceller and a signal level on said transmitting side, and gain/loss computing means responsive to said echo rejection level from said ERL determining means and a gain for the output of the echo canceller for computing a gain and a loss in a predominant voice condition and a gain and a loss in an inferior voice condition;
audio bridge circuit means having a respective adder means for each said channel signal processing circuit, each of said adder means adding the outputs of the echo cancellers, level-adjusted by said level adjusting means, except for the respective echo canceller, and supplying a resulting sum signal to said transmitting side of the respective channel signal processing circuit via the respective level adjusting means; and
a predominant channel detection means for comparing respective output levels of said echo cancellers for judging whether the channel condition of the channel signal processing circuit including the echo canceller having a maximum output level is predominant and for judging whether the channel conditions of the remaining channel signal processing circuits are inferior, thereby to control the level adjusting means provided in the channel signal processing circuit judged to be predominant on the basis of said gain and loss in said predominant voice condition from said gain/loss computing means of the predominant channel signal processing means and to control the respective level adjusting means provided in the channel signal processing circuits judged to be inferior on the basis of said gain and loss in the respective inferior voice condition from the respective gain/loss computing means of the remaining channel signal processing means.
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Accused Products
Abstract
An audio bridge for a telephone conference is disclosed. The audio bridge; comprises a channel signal processing unit assigned to at least three channels. Each channel signal processing circuit comprises an echo canceller to cancel an echo signal from the transmitting side fed back to the receiving side, an amplifier and attenuator circuits to adjust levels of an output of the echo canceller and a transmitting signal transmitted through the channel signal processing circuit, an ERL determining circuit to determine an echo cancellation on the basis of the output from the echo canceller and a signal level on the transmitting side, and a gain/loss computing circuit to compute a loss in a predominant voice condition and a gain and a loss in an inferior voice condition. The speech audio bridge further comprises audio bridge circuits which add the outputs of the amplifier circuits provided in the channel signal processing circuits except for the one assigned to itself, and a predominant channel detection unit for detecting a predominant channel and inferior channels on the basis of output levels of the amplifier circuits to suitably control the gain and loss of each channel according to the predominant and inferior voice conditions. Thus, this equipment makes it possible to prevent "singing" due to the variation of the cancellation with time.
131 Citations
13 Claims
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1. An audio bridge for a conferencing system, comprising:
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channel signal processing means comprising at least three channel signal processing circuits, each of said channel signal processing circuits including, respectively, a receiving side for receiving a channel signal, a transmitting side for transmitting a channel signal, an echo canceller for cancelling an echo signal fed back to said receiving side from said transmitting side, means for adjusting levels of an output of said echo canceller and a transmitting signal transmitted through the transmitting side of said channel signal processing circuit, ERL determining means for determining an echo rejection level on the basis of said output from said echo canceller and a signal level on said transmitting side, and gain/loss computing means responsive to said echo rejection level from said ERL determining means and a gain for the output of the echo canceller for computing a gain and a loss in a predominant voice condition and a gain and a loss in an inferior voice condition; audio bridge circuit means having a respective adder means for each said channel signal processing circuit, each of said adder means adding the outputs of the echo cancellers, level-adjusted by said level adjusting means, except for the respective echo canceller, and supplying a resulting sum signal to said transmitting side of the respective channel signal processing circuit via the respective level adjusting means; and a predominant channel detection means for comparing respective output levels of said echo cancellers for judging whether the channel condition of the channel signal processing circuit including the echo canceller having a maximum output level is predominant and for judging whether the channel conditions of the remaining channel signal processing circuits are inferior, thereby to control the level adjusting means provided in the channel signal processing circuit judged to be predominant on the basis of said gain and loss in said predominant voice condition from said gain/loss computing means of the predominant channel signal processing means and to control the respective level adjusting means provided in the channel signal processing circuits judged to be inferior on the basis of said gain and loss in the respective inferior voice condition from the respective gain/loss computing means of the remaining channel signal processing means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification