JPH03216052A - Voice conference communication system between multi-points - Google Patents

Abstract

PURPOSE:To attain multi-point voice conference into which plural conference rooms participate simultaneously by setting a voice conference network with a terminal switch, applying band compression to a voice signal of each conference room, applying multiplexing/demultiplexing to the signal and sending/receiving the signal. CONSTITUTION:The device is provided with a terminal changeover switch 40 selecting either a voice conference terminal equipment 20 or a subscriber telephone set 30, a 2/4-wire conversion circuit 51, a PCM hand compressor 50 comprising a CODEC 52 applying band compression of an analog transmission of a voice band into a PCM signal and a multiplexer/demultiplexer 60 multiplexing/demultiplexing an input output signal of the plural PCM band compressors 50. Then a conference room being a sponsor dials a subscriber of other conference room from the subscriber telephone set 30, the other conference room replies with the dial signal to select a terminal changeover switch 40 to the voice conference terminal equipment 20 and when the call is finished, the terminal changeover switch 49 of a conference room A is selected to the voice conference terminal equipment 20 to form a voice conference network. Thus, the conference is simply held by having only to dial an opposite subscriber number.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an audio conference device, and more particularly to a multipoint audio conference device using a high-speed digital line.

[Conventional technology]

Conventionally, this type of multipoint audio conference has been based on an analog signal system in which audio conference terminal devices are installed in each of a plurality of conference rooms, and these audio conference terminal devices are branched and connected using dedicated lines.

When holding a multipoint audio conference between multiple conference rooms, each conference room manually turns on the commercial power of the audio conference terminal device individually at a predetermined conference holding time and waits until the conference is held. Therefore, before a conference is held, the host conference room calls each conference room to confirm whether or not each conference room is in a standby state.

Furthermore, in the case of audio conferences using public address telephone equipment using subscriber lines, one-on-one face-to-face conferences were held.

[Problem to be solved by the invention]

The conference network settings for analog multipoint audio conferences using conventional branch connections using dedicated lines as described above require attendees in each conference room to turn on the commercial power to the audio conference terminals installed in the conference room themselves. Therefore, if attendees were late, the meeting would be delayed.

Furthermore, if the meeting is held on time with some conference rooms not participating, it will be unclear when the audio conference terminal device in the conference room that was late was turned on unless the conference attendee makes a statement, and the host will not be able to tell. It was necessary for the conference room to call from time to time to check whether the conference room was participating.

Furthermore, in the case of voice conferences using public address telephone equipment that uses subscriber lines, there is a drawback that multipoint voice conferences cannot be held because the same transmission band as that of ordinary telephone equipment is used.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multipoint audio conference device that allows simultaneous participation in multiple conference rooms, is easy to operate, and is economical. [Means for Solving the Problems] The multipoint audio conference device of the present invention has the following features:1. A plurality of microphones that collect audio signals, a speaker that amplifies the received audio signal from the conference room of the other party, and a reception loop where the received audio signal output from the speaker is collected by the microphone via an acoustic path. a first echo canceller that removes the transmission line; a 2/4-wire conversion circuit that interfaces with the transmission line; 2nd to remove
A multi-point audio conference device that connects audio conference terminal devices equipped with an echo canceller via a subscriber line to conduct a conference includes a subscriber telephone device and a subscriber telephone device for calling a required conference room and setting up an audio conference network. , a terminal switching device for switching from the subscriber telephone device to the audio conference terminal device after setting up the audio conference network; and an analog transmission audio signal of the subscriber telephone device or audio conference terminal device to which the terminal switching device has switched. It has a PCM band compression device that performs band compression and PCM encoding or decoding a PCM encoded received voice signal into an analog signal.

2. a multiplex transmitting unit that multiplexes band-compressed PCM encoded transmitting and receiving audio signals outputted by the multipoint audio conferencing device of item 1 above and outputs the same to a high-speed digital line; and and a separating/receiving section that separates the PCM encoded received voice signals individually and connects them to the audio conference terminal device.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a multipoint audio conference device according to an embodiment of the present invention, and FIG. 2 is a block diagram of a multipoint audio conference system using the audio conference device according to an embodiment of the present invention.

FIG. 1 shows microphones 1, 2, 3, and 4 that collect the voices of conference participants, a speaker 15 that amplifies the received voice signals from the other conference room, and voice signals collected by the microphones 1 to 4. a transmitting amplification circuit 5 for amplifying to a predetermined level;
An A/D conversion circuit 6 converts the analog audio signal outputted by the transmitting amplifier circuit 5 into a digital signal, and the receiving audio signal is converted from the digital signal containing the receiving audio signal collected from the speaker 5 to the microphones 1 to 4 via the acoustic path. An echo canceller 7 that removes the loopback signal, and a D/A conversion circuit 8 that converts the outgoing audio signal from which the loopback signal has been removed into an analog signal.
, a 2/4-line conversion circuit 9 that converts the analog outgoing voice signal outputted by the D/A conversion circuit 8 into a 2-wire signal, and D that converts the received voice signal outputted by the 2/4-line conversion circuit 9 into a digital signal.
/A conversion circuit 10, an echo canceller 10 for removing the transmitting audio signal leaking from the 2/4 line converting circuit 9, a receiving level adjustment circuit 12 for variably adjusting the level of the receiving audio signal from which the transmitting wrap-around signal has been removed, and a predetermined D/A conversion circuit 13 that converts the level-adjusted received audio signal into an analog signal
, and a power amplification circuit 14 that amplifies analog received audio signals to a predetermined listening sound pressure level.
, a subscriber telephone device 30, a terminal changeover switch 40 for selecting either the voice conference terminal device 20 or the subscriber telephone device 30, and an interface with the voice conference terminal device or the subscriber telephone device via the terminal changeover switch 40. do 2/
4 conversion circuit 51, a PCM band compression device 50 consisting of a codec 52 that band-compresses a voice band analog transmission signal into, for example, a 16 Kbps PCM signal, and a plurality of PCs.
It is composed of a multiplexing/demultiplexing transmission device 60 that multiplexes and demultiplexes input/output signals of the M-band compression device 50.

FIG. 2 shows conference rooms A, BC, D, E, F, G, and H in which the audio conference terminal device 20, subscriber telephone device 30, terminal changeover switch 40, and band compression device 50 shown in FIG. 1 are installed.
is installed in one of the conference rooms A to H or the center, and transmits the audio signals of the conference rooms A to H, for example, 64K.
It is composed of a multiplexing and demultiplexing transmission device 60 for connecting to a bps high-speed digital line.

Next, in FIG. 2, a five-point audio conference between conference rooms B, C, D, and E, with conference room A as the host, will be described as an example.

First, conference room A, which is the conference organizer, dials conference room B's subscriber number from subscriber telephone equipment 830 to call conference room B. After conference room B responds, the terminal changeover switch 40 of conference room B is switched from the subscriber telephone device to the audio conference terminal device. Next, conference room A once takes the subscriber telephone device 30 off-hook, and then dials conference room C's subscriber number. After receiving the call, conference room C responds similarly to conference room B, and then switches the terminal changeover switch 40 of conference room C to the audio conference terminal device 20.

In this way, conference room A sequentially calls conference rooms D and E, and when the predetermined participating conference rooms B, C, D, and E are completely called,
The terminal changeover switch 40 in the conference room A is connected to the audio conference terminal device 2.
0, and a five-party audio conference network is formed.

For example, conference rooms A and B whose bandwidth is compressed to 16Kbps,
The transmission audio signals of C and D are multiplexed by a multiplexing/separating transmission device 60-1 and connected to a multiplexing/separating transmission device 602 via a high-speed digital line 80-1, a switching device 70, and a high-speed digital line 80-2. be done. Multiplex/separate transmission device 60
-2, a 64 Kbps transmission audio signal in which the audio signals of conference rooms A, B, C, and D are multiplexed is connected to the band compression device 50 of conference room E. In conference room E, the band compression device 50
After the 4 Kbps digital signal is decoded into an analog signal, it is converted into 2/4 wire and connected to the audio conference terminal device 20 via the terminal changeover switch 40. Audio conference terminal device 20
Audio signals from conference rooms A to D connected to the 2/4 line conversion circuit 9, A/D conversion circuit 10, echo canceller 11,
Through the reception level adjustment circuit 12 and the D/A conversion circuit 13,
The signal is amplified by the power amplification circuit 14 and amplified by the speaker 15 at a predetermined sound pressure level.

The transmitted audio signal from conference room E is transmitted to band compression device 60-2.
, high-speed digital circuit 118 0-2, switching device 70
, are connected to the multiplex/separate transmission device 60-1 via a high-speed digital line 80-1. The multiplexing/demultiplexing transmission device 60-1 separates the received audio signal from the conference room E from other channels and outputs it to the band compression device 50 of each conference room A, B, C, and D. In the band compression device 50 of each conference room, the PCM band-compressed received audio signal from the conference room E is decoded into an analog signal, converted into a 2-wire signal by a 2/4-wire conversion circuit 51, and then transmitted via the terminal changeover switch 40. and connect to the voice conference terminal W20. Audio signals from the conference room E connected to each audio conference terminal device 20 are transmitted through a 2/4 line conversion circuit 9, an A/D conversion circuit 10, an echo canceller 11, and a reception level adjustment circuit 12.
, a D/A conversion circuit 13, amplified by a power amplifier circuit 14, and amplified by a speaker 15 at a predetermined sound pressure level. In this way, a multipoint audio conference is held between conference rooms that are separated from each other.

In the above explanation, the case where an audio conference device is installed in each conference room has been explained. However, in a relatively large conference room, for example, a loudspeaker telephone device with a built-in microphone and subwoofer can be used for multipoint audio conferences. If the sound pressure from the microphone or speaker is insufficient,
It is also possible to install, for example, four loudspeaker telephone devices in one conference room, and to multiplex and separate the input and output of each loudspeaker telephone device by the multiplexing/separating transmission device 60 to produce an output signal for one conference room. In addition, although we have shown an example of multiplexing and separating the transmitting and receiving audio signals of four conference rooms, for example, it is possible to construct a multipoint audio conference system that allows even more conference rooms to participate simultaneously by using the ISDN H channel. is easily possible.

Although we have shown an example in which audio signals from four conference rooms are compressed to 16 Kbps and transmitted at 64 Kbps, transmitting and receiving audio signals from two conference rooms are each compressed to 32 Kbps and then multiplexed to transmit at 64 Kbps. Of course, it is also possible to transmit the information by .

Furthermore, instead of calling each conference room individually using the subscriber telephone device, the subscriber number of the participating conference room is input in advance.
For example, it is easily possible to make a simultaneous call by pressing a simultaneous call button or the like.

〔Effect of the invention〕

As explained above, the present invention enables multipoint audio conferences in which multiple conference rooms participate simultaneously by band-compressing the audio signals of each conference room, multiplexing and separating the audio signals of multiple conference rooms, and transmitting and receiving them. It becomes possible.

In addition, subscriber lines are not only economical because they are charged based on usage frequency, rather than a fixed amount like leased lines, but they also do not require complicated operations or procedures even in an emergency, and dial the other party's number. The effect is that you can easily hold a meeting just by doing this.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a multipoint audio conference device according to an embodiment of the present invention, and FIG. 2 is a block diagram of a multipoint audio conference system using the audio conference device according to an embodiment of the present invention. 1 to 4...Microphone, 5...Speech amplification circuit, 6
, 10... A/D conversion circuit, 7... Acoustic echo canceller, 8.13... D/A conversion circuit, 9, 51...
- 2/4 wire conversion circuit, 11... Transmission echo canceller, 12... Receiving level adjustment circuit, 14... Power amplifier circuit, 15... Subi-ka, 20... Audio conference terminal device, 30... Subscriber telephone device, 40... Terminal changeover switch, 50... Bandwidth compression device, 52... Codec, 60.60-1.60-2... Multiplexing/separating transmission device, 70 ... Switching equipment, 80-1.80-2 ... High-speed digital line, A to H ... Conference room.

Claims (1)

[Claims] 1. A plurality of microphones that collect audio signals, a speaker that amplifies the received audio signal from the other conference room, and the received audio signal output from the speaker is transmitted to the microphone via an acoustic path. a first echo canceller that removes the feedback of the collected sound; and a second echo canceller that interfaces with the transmission path.
A subscriber is provided with an audio conference terminal device equipped with a 4-wire conversion circuit and a second echo canceller that eliminates loopback of the transmitted audio signal caused by impedance mismatch between the 2/4-wire conversion circuit and the transmission path. In a multipoint audio conferencing device that connects via a line and conducts a conference, there is a subscriber telephone device for calling a required conference room and setting up an audio conference network, and a subscriber telephone device for calling a required conference room and setting up an audio conference network, and from the subscriber telephone device after setting up the audio conference network. A terminal switching device for switching to the audio conference terminal device, and band compression and PCM encoding or PCM encoding reception of the analog transmission audio signal of the subscriber telephone device or audio conference terminal device switched by the terminal switching device. A multipoint audio conferencing device comprising a PCM band compression device that decodes audio signals into analog signals. 2. A multiplex transmitter that multiplexes the band-compressed PCM encoded transmitting/receiving audio signals output from the multipoint audio conferencing device according to claim 1 and outputting the same to a high-speed digital line; A multipoint audio conferencing device comprising a digital multiplexing and demultiplexing device that separates a plurality of PCM encoded received audio signals individually and connects to the audio conference terminal device. .