JPS60226262A - Control system for conference telephone call - Google Patents

Abstract

PURPOSE:To prevent the additive distribution of a speech signal in a state where an echo component is not suppressed sufficiently by inputting the speech signal to a speech adding part at the end of the training of an echo canceler. CONSTITUTION:When channel numbers of conference attendant subscribers, e.g. 1, 2, and (n) are specified with conference control information, a control part 3 turns off switch circuits 5-1, 5-2, and 5-n and commands the speech adding part 2 to add and distribute speech signals of channels 1, 2, and (n); and switch circuits 7-1, 7-2, and 7-n are turned off and a signal generating part 6 is actuated to send out a training signal to echo cancelers 4-1, 4-2, and 4-n for a specific time. In this case, the switch circuits 5-1, 5-2, and 5-n are controlled to the off state, so there is no speech signal input to the speech adding part 2 and the additive distribution is not performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention is directed to a conference telephone that enables calls between multiple channels, in which multiple channels are connected within a short period of time when a subscriber participating in the conference is called. The present invention relates to a conference call control method that prevents ringing from occurring.

Conventional Examples and Problems In conference telephones that call multiple participants in a conference simultaneously or sequentially and connect them via a conference telephone device so that they can talk to each other, echoes due to hybrid circuits, etc. An echo canceller is provided to compensate for the component. Various configurations of this echo canceller have already been proposed, and the echo canceller generally estimates the characteristics of the echo path based on the speech signal. Therefore, in a conference telephone device, if conference participants are called simultaneously and each conference participant responds at the same time, each channel may be connected without sufficient echo canceller convergence. become. If multiple channels are connected without sufficient convergence of the echo canceller, the echo components will not be canceled sufficiently, and a multiple closed loop of echo components will occur, including the conference telephone equipment, resulting in a ringing state. be. When this kind of noise occurs, the service deteriorates significantly.

For this reason, conventionally, when connecting a plurality of channels, each channel was connected in sequence with sufficient time intervals. Therefore, when there are many participants participating in a conference, there is a drawback that it takes a long time until the connections of all participants participating in the conference are terminated.

OBJECTS OF THE INVENTION The object of the present invention is to efficiently train an echo canceller when calling a subscriber participating in a conference call, and to connect multiple channels in a short time without causing a ringing state. be.

Structure of the Invention The present invention provides a conference telephone system that enables mutual communication in a plurality of channels using a conference telephone device equipped with an echo canceller, and a signal generating means for generating a training signal for the echo canceller, and the conference telephone device. switch means for controlling the input of audio signals to the audio adder in a channel-based manner, and when a connection to the conference telephone device is started by a call response of a subscriber participating in the conference, the input of the audio signal to the audio adder is controlled according to the channel; The switch means blocks the input of the voice signal of the person participating in the conference, and sends a training signal from the signal generating means to an echo canceller capable of connecting with the subscriber participating in the conference, and when the training of the echo canceller is completed, the training signal is The signal transmission is stopped and the audio signals of the participants participating in the conference are manually inputted to the audio adding section via the switching means, and an embodiment thereof will be described in detail below.

Embodiment of the invention FIG. 1 is a block diagram of main parts of an embodiment of the invention.
1 is a conference telephone device, 2 is an audio addition section, 3 is a control section, 4-
1 to 4-n are channel-compatible echo cancellers, 5-1
5-n are switch circuits, 6 is a signal generator that generates training signals, 7-1 to 7-n are switch circuits that control sending and stopping of training signals, and 8 is a time division switching device. The time division switching device 8 is composed of a time division communication path, a central control unit, a multiplexer, a demultiplexer, etc., and is connected to the conference telephone device f via an internal highway. This shows the case where it is connected.

The audio signal of each channel is inputted to the audio adder 2 via the echo cancellers 4-1 to 4-n and the switch circuits 5-1 to 5-n, and the audio signals of the participants participating in the conference are added. The echo cancellers 4-1 to 4-n are separately delivered. Such an audio adder 2 can adopt various known configurations. For example, in a conference call between subscribers A-D, if the audio signals are indicated as the same code, the audio signals for subscriber A The signal is (A0B0C+D
)-A, and the signal for subscriber B is (A+B+C+D
)-B, and the signal for subscriber C is (A+B+C+D
) −〇, and the signal for each subscriber is (A+B+C+
D)-, D is calculated and sent.

When conference control information is transferred from the time-sharing exchange bag N8 to the conference telephone device 1 in response to a call response from a subscriber participating in the conference, the control section 3 decodes the conference control information and sends it to the switch circuit 5.
-1 to 5-n and the audio adder 2 are controlled. For example, the conference control information indicates that the channel number of the subscriber participating in the conference is 1.
．． 2. When specified as n, the control unit 3 controls the switch circuit 51.5-2.5-n to turn off,
Then, it instructs the audio adder 2 to add and distribute the audio signals of channel numbers 1, 2, and n, and turns on the switch circuit 7-1.7-2.7-n to turn on the signal generator 6. Start and train the echo canceller 4-
1. 4-2. 4-n.

In the time division switching device 8, the channel settings for the conference participating subscribers have already been performed, and the connection with the conference telephone device 1 has been established in response to a call response from the conference participating subscribers.
Since the switch circuit 5-1.5-2.5-n is controlled to be in the off state, the audio signal input to the audio adder 2 is zero, and the distribution signal is also zero, so there is no sounding state. This will no longer be the case. Also switch circuit 5-1.5
-2.5-n is off, echo canceller 4 1
, 4-2. A training signal is sent from the signal generator 6 to the echo cancellers 4-1 .
4-2. 4-n training is performed.

The transmission period of this training signal can also be set as a certain period of time set in advance so that the training ends. In this case, the control unit 3
1. 7-2. The time can be measured using a timer or the like from the time when 7-n is turned on, and the control can be performed so that it is turned off at a predetermined time. It is also possible to wait until all the participants participating in the conference have responded, and in this case, the switch circuit ? -1, 7-2, and 7-n can be controlled to be turned off.

Switch circuit 7-1~? By turning off -n,
The audio addition results are distributed to the channels of participants participating in the conference.

As described above, when conference participants are connected to the conference telephone device 1, the input of audio signals to the audio adder 2 is blocked by controlling the switch circuits 5-1 to 5-n, and the echo canceller 4- After training 1 to 4-n is completed, it is possible to prevent the locusts from generating noise. Also switch circuit 5
Since training can be performed by sending the training signal from the signal generator 6 to the echo canceller during the period when -1 to 5-n are turned off, training can be performed reliably.

FIG. 2 is a block diagram of another embodiment of the present invention, in which the same reference numerals as in FIG. It is about the case. The training signal from the signal generator 6 is transferred to the conference telephone device 1 via the time division switching device 8. For example, as in the previous case, channel numbers 1, 2, . When n is specified as a channel of a subscriber participating in a conference, and if the signal generator 6 is connected to a specific channel number j in the time division switching device 8, that information and conference control information are transferred to the controller 3. Therefore, the control section 3 turns on the switch circuit 5-j of the channel to which the signal generation section 6 is connected, and turns on the switch circuit 5-j of the channel to which the signal generation section 6 is connected.
-1.5-2°5-n is off. Therefore, the audio signals with channel numbers 1, 2, and n are not input to the audio adder 2, but the training signals from the signal generator 6 are input to the echo canceller 4-j by the channel number j.
and the switch circuit 5-j to the audio adder 2.

The audio adder 2 receives channel numbers 1, 2, . . . from the controller 3.
The training signal inputted via the switch circuit 5-j is distributed to the echo cancellers 4-1.4-2.4-n since it is controlled to add and distribute the audio signals of j and H. . Thereby echo canceller 4-1.4
-2.4-n training will be performed. Then, the switch circuit 5-j is turned off after a certain period of time or when all the participants participating in the conference have completed their responses, and the switch circuit 5-1 is turned off.
．． 5-2. By turning on 5-n, channel numbers 1, 2, . n audio signals are input to the audio adder 2, and a conference call is performed by addition and distribution.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention includes signal generating means for generating training signals for the echo cancellers 4-1 to 4-n such as the signal generating unit 6, and a signal generating unit for generating training signals for the echo cancellers 4-1 to 4-n such as the signal generating unit 6, and A switch means consisting of switch circuits 5-1 to 5-n, etc., for controlling the input of audio signals in accordance with channels is provided, and when a conference participant starts connecting with the conference telephone device 1 in response to a call, voice addition is performed. It prevents audio signal input to the section 2, and sends a training signal to the echo cancellers 4-1 to 4-n.
When the training of the worker cancellers 4-1 to 4-n is completed, the transmission of the training signal is stopped and the audio signal is input to the audio adder 2. 2, the addition and distribution of audio signals will not be performed in a state where the echo component is not sufficiently suppressed, and therefore no sound will occur. Therefore, it becomes possible to connect conference participants who respond to calls in a short time. Further, since the signal generating section 6 that generates the training signal can be placed in various positions, it can be easily applied to an existing exchange system.

[Brief explanation of the drawing]

1 and 2 are block diagrams of different embodiments of the present invention. ■ is a conference telephone device, 2 is an audio addition section, 3 is a control section, 4-
1 to 4-n are echo cancellers, 5-1 to 5-n are switch circuits, 6 is a signal generation diagram, 7-1 to 7-n are switch circuits, and 8 is a time division switching device. Figure 1 8

Claims (1)

[Claims] In a conference telephone system that enables mutual calls on multiple channels using a conference telephone device equipped with an echo canceller,
Signal generation means for generating a training signal for the echo canceller; and switch means for controlling the input of audio signals to the audio adder of the conference telephone device in accordance with the channels; When the connection with the telephone device is started, the switch means prevents input of the audio signal of the subscriber participating in the conference to the audio adding section, and the training signal from the signal generating means is connected to the subscriber participating in the conference. It is sent to the corresponding echo canceller, and when the echo canceller completes its training,
A conference telephone call control system, characterized in that transmission of the training signal is stopped and the audio signal of the subscriber participating in the conference is input to the audio adding section via the switch means.