JPH0526382B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a bridge circuit for a conference call transmitting/receiving device;
In particular, the present invention relates to a bridge circuit for a conference call transmitting/receiving device that connects to each transmitting/receiving circuit in a plurality of zones in which a large conference room is divided, connects and distributes audio signals, and communicates with the other conference room.

[Conventional technology]

Conventionally, a patent application filed in 1983 was developed as a conference call transmitter/receiver that can acoustically cover the entire room without producing reverberant echoes or howling even when installed in a large conference room.
The device described in specification No. 153221 has been proposed.
This device assumes multiple zones within one conference room, and includes a transmitting circuit for guiding audio signals emitted from microphones in each zone, and a transmitting circuit for guiding audio signals received from the other party's conference room to speakers in each zone. It has a configuration in which an echo canceller is connected to the receiver circuit for canceling indoor echoes within each zone and between indoor echoes between the zones. This device distributes the audio signals led from the transmitting circuit in each zone to the receiving circuits in other zones, adds up all the audio signals given from the transmitting circuit in each zone, and sends the sum to the other conference room. A bridge circuit (described as a branch circuit 5 in the above-mentioned specification) is provided in order to emit a signal to communicate with the other conference room and to distribute the audio signal received from the conference room to the receiving circuits of each zone.

[Problem that the invention seeks to solve]

The conventional bridge circuit for a conference call transmitting/receiving device described above adds up all the audio signals given from the transmitting circuits of each zone as they are, and sends out a signal to be transmitted to the other party's conference room. However, when actually transmitting a call, a certain zone, for example zone A,
When someone makes a speech, an audio signal is emitted from the microphone in zone A to the transmitting circuit, and at the same time, the speech is routed to the microphone in another zone, for example, zone B, and an audio signal is also sent to the transmitting circuit in zone B. Emitted. In such cases, zone B is usually
The audio signal generated in zone A is accompanied by a lower level and a time delay compared to the audio signal in zone A. The conventional bridge circuit adds the audio signals of both zones A and B as they are and sends the result as a signal to be transmitted to the other party's conference room. As a result, when this is received in the other party's conference room and reproduced through a speaker, there is a problem that the reproduced sound becomes unclear and contains reverberation, making it difficult to hear.

In order to solve the above-mentioned problems, an object of the present invention is to emphasize and add relatively high-level audio signals among the audio signals provided from the transmission circuits of multiple zones, so that clear reproduction can be achieved in the other party's conference room. An object of the present invention is to provide a bridge circuit for a conference call transmitting/receiving device which allows sound to be obtained.

[Means for solving problems]

The circuit of the present invention is connected to a plurality of sets of transmitting circuits and receiving circuits provided corresponding to a plurality of zones in one conference room, and transmits signals arriving from the transmitting circuit of each zone to those other than the own zone. a plurality of expanders that detect the level of the incoming signal after being distributed to the receiving circuit of the incoming signal, and amplify the level change of the incoming signal by amplifying it with a gain determined corresponding to the level; One adding means for adding and sending out the sending signals and a level characteristic such that the gain sum of each of the expanders is a predetermined value, compressing the level change of the sending signal of the adding means and sending it to the other party. comprising one compressor for transmitting a signal, and a plurality of superimposing means for distributing the received signal from the other party, superimposing the signal distributed from the transmitting circuit on this, and applying it to the receiving circuit of each zone. There is.

〔Example〕

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

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a characteristic diagram for explaining its operation.

FIG. 1 shows a case where a large conference room is divided into two zones, zones A and B. It is easy to extend to cases of three or more zoning.
Transmission signals S _A and S _B are audio signals sent from respective transmission circuits in zones A and B, and are sent to expanders 1A and 1B, and are also sent via attenuators (ATT) 4A and 4B. and is led to adders 5B and 5A in other zones. Both expanders 1A and 1B are syllabic expanders having the same level characteristics, and have level characteristics of characteristic E illustrated by the solid line in FIG. Characteristic E means that the average level (input level) of the input signal is between Lm and
Between L _M (dBr), the gain increment changes proportionally to the input level increment, and the input level
The gain is constant in the range below (dBr) or above L _M (dBr). Each stretcher 1A and 1
B detects the average level of the input signal, amplifies the input signal with a gain determined by the characteristic E according to the detection result, and transmits the amplified signal. Adder 2 adds the signals provided from expanders 1A and 1B of both zones, and sends the addition result to compressor 3. The compressor 3 is a syllabic compressor having a level characteristic such that the gain sum with each of the expanders 1A and 1B becomes a predetermined constant value, and detects the level of its own sending signal and uses the detection result. A signal amplified with a gain determined accordingly is sent as a transmission signal S to be transmitted to the conference room of the other party. On the other hand, the received signal R arriving from the other party's conference room is branched and then guided to adders 5A and 5B in each zone. Adders 5A and 5B each add the branched received signal R and the audio signal given from other zones via ATTs 4B and 4A, and send the resultant signals to the receiving circuit of its own zone as received signals R _A and R _B. Send.

For example, when a speech is made in zone A, a transmission signal S _A correspondingly arrives at the expander 1A, and a transmission signal S _B generated when the speech in zone A wraps around to zone B is transmitted to the expander 1B. Arrival. In this case, the sending signal S _B is accompanied by a lower level and a time delay than the sending signal _SA . In this embodiment, the difference between the average level of the transmitting signal in the transmitting zone and the average level of the transmitting signal in the non-transmitting zone is, after passing through the expander 1,
The stretching ratio increases to twice that of . For example, when the expansion ratio is 2, that is, when the input level is (Lo + l) (dBr) in Fig. 2 (provided that Lm < (Lo + l) < Lm holds), the gain is (Go + l).
(dB), the level difference between the transmitting signal during transmitting and the transmitting signal during non-transmitting increases to twice as much after expansion. As a result, in the output signal of the adder 2, the transmission signal of the zone in which talking is in progress is emphasized, and the transmission signal in the zone in which speaking is not in progress is suppressed relative to this. The compressor 3 amplifies the transmitted signals while maintaining emphasis on the level difference, and therefore emphasizes the relatively higher level of the transmitted signals S _A and S _B of both zones, and A transmission signal S is obtained in which the lower one is suppressed. In this way, by emphasizing and adding the relative level difference between the transmitted signals in both zones, reverberation caused by wraparound between the zones is suppressed, and clear reproduced sound can be obtained in the other party's conference room. A transmission signal S can be obtained.

[Effects of the Invention] As described above, the present invention has the effect of realizing a bridge circuit for a conference call transmitting/receiving device that allows clear reproduced sound to be obtained in the other party's conference room.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a characteristic diagram for explaining the operation of the embodiment of the present invention. 1A, 1B...Extender, 2, 5A, 5B...Adder, 3...Compressor, 4A, 4B...Attenuator (ATT).

Claims (1)

[Claims] 1 Connected to multiple sets of transmitting circuits and receiving circuits provided corresponding to multiple zones in one conference room, and transmitting signals arriving from the transmitting circuit of each zone to the receiving circuits in zones other than the own zone. After distribution, a plurality of expanders detect the level of the incoming signal and amplify it with a gain determined corresponding to the level to expand the level change of the incoming signal, and add the signals sent out from the plurality of expanders. one adding means for transmitting a signal, and one having a level characteristic such that the sum of gains of each of the expanders is a predetermined value, compressing level changes in a signal sent from the adding means and transmitting a signal to the other party. and a plurality of superimposing means for distributing the received signal from the other party, superimposing the signal distributed from the transmitting circuit on the received signal, and applying the superimposed signal to the receiving circuit of each zone. Bridge circuit for conference call transmitting and receiving equipment.