JPS59264A - Conference calling method - Google Patents

Abstract

PURPOSE:To prevent deterioration of a quality of a conference call, by realizing the conference call by use of two channels for executing alternately addition and distribution. CONSTITUTION:Terminal stations 2a-2d control switches S1-S4 as prescribed, therefore, a frame F1 inputs contents of a channel CHj and outputs them to each telephone set 3a-3d, and adds outputs of the telephone sets 3a-3d to the channel CHi. As a result, a result of addition of sound signals of the telephone sets 3a, 3b, 3c and 3d is obtained in the input side of the channel CHi of a synchronizing device 8. The contents of this frame F1 are delayed by a constant interval of time by a delaying circuit 9 as prescribed, and after that, are outputted by the timing of a frame F2. Subsequently, the addition result is outputted as the contents of the CHi from the device 8. On the other hand, the contents of the channel CHj, which are outputted from the device 8 are cleared in accordance with an operation of a switch S5. Also, in the frame F2, the operation which entirely reverses the preceding operation is executed, and the conference call is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conference call method (hereinafter referred to as the method) between telephones housed in loosely coupled terminal stations.

Conventionally, a conference call using a channel multiplexing system configured in a loop has been carried out using the configuration shown in FIG. In the figure, (1) is one time-division communication channel on a channel multiplexed loose transmission path, and is not an actual transmission path itself, but a conceptual representation of that one time-division communication channel. (2a) to (2d) are terminal stations placed on the loop transmission path, and (3a) to (3d) are terminal stations (2m) to (2d).
), the telephones (4m) to (4d) convert the analog voice signals from the telephones C3λ) to (3d) into digital signals, and also provide time-division communication channels (1).
C0 converts the above digital signal into an analog audio signal
DEC, (51) to (5d) are the GODEC (4a)
Adders that add the audio signals digitized by ~(4d) to the outputs of subtracters (7a) to (7d), which will be described later, and (6a) to (6d) hold the audio signals while they go around the loop. (7λ) to (7d) are subtractors that subtract the contents of registers (6a) to (6d) from the audio signal from the previous terminal station, and (8) is a synchronization signal to maintain frame synchronization. It is a synchronizer that occurs.

Next, let's talk about the operations fi (3a), (3b),
The case of (3C) and (3d) during a meeting will be explained. Each terminal station C2m on the time division communication channel (1)
Adder (5a) to (5d) (7) of ~(2d) - Koyori, IEFT [(311)* (3b), (3C)
The signal obtained by digitally adding the audio signals from , (3d) is looped once. The terminal station (2a) subtracts the contents of the register (6a) from this circulating signal using the subtractor σ, and thereby each telephone set (3b)t (3c), (3d
) to obtain a digital signal with added audio. Then, the terminal station C sends the digital signal to the telephone (3m), adds the digitized voice signal from the telephone (3a) to the digital signal, and sends the digital signal to the terminal station (2b).
Send to. In addition, the digitized audio signal from the telephone is used for the above addition and is stored in the register (6a).
is also accumulated. This is to hold the signal for subtraction after the loop. Then, by performing similar operations at other terminal stations, telephones (3a) and (3b) are created.

A conference call between (3c) and (3d) is realized.

Conventional conference calls using a channel multiplexing method configured in a loop are realized as described above, so there is a risk that the effects of transmission errors and overflow of addition results will accumulate, and there is also a risk of accumulation of effects due to changes in the loop travel time. This had drawbacks such as the register configuration becoming complicated.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it uses two time-division call channels for conference calls, and one channel is used to add the audio signals of the conference participants. Alternately switching between using one channel as an addition channel and using the other channel as a distribution channel for distributing the added audio signal, and using one channel as a distribution channel and the other channel as an addition channel. The purpose of this invention is to provide a conference call method in which the effects of transmission errors and addition result overflows are not accumulated, and the registers as described above are not required.

An embodiment of the present invention will be described below with reference to the drawings. Second
The figure shows an example of a frame structure of a time division multiplexed loose transmission line to which the present invention is applied. In the figure, GF is a dog frame, Fl and F2 are frames forming the dog frame GF, SYN is a synchronization signal, and CHI to CHn are the first
〜nth channel O In the present invention, C: Hi and CHj
is used for conference calls.

FIG. 3 shows an example of the hardware configuration of the present invention. In FIG. This is a conceptual representation of a channel. (2a)
~(2d) is a terminal station placed on the loop transmission path, (3m
) - (3d) is the telephone housed in the terminal station (2a) - (2d), (4a) to (4d) are C0DEC% (
5a) to (5d) are adders that add the digitized audio signals, and Sl selects either channel CHi or CHj and sends the audio signal to the GODEC (4a).
- (4d) input switch, 82 is channel CH
a switch for selecting either i or CHj and inputting the audio signal to the adders (5a) to (5d); s3.
s4 outputs the outputs of adders (5a) to (5d) to channel C.
)li, This is a switch for selecting whether to output to CHj. (8) is a synchronization device that generates a synchronization signal to maintain frame synchronization, and S5yS6 is a synchronization device that generates a synchronization signal to maintain frame synchronization.
This is a switch that selects whether or not to output Hi and CHj inputs. (9) is a delay circuit that outputs the received frame after it has been delayed for a certain period of time. Furthermore, the above switches 51 to S6
This switch does not actually exist, but is provided to conceptually explain the operation when time-division multiplexing each audio signal to each time-division communication channel.

Next, the operation will be explained. frame) 1 channel C
Hi is used to add the audio signals of conference participants,
Channel CHj is used to distribute the added audio signals. In frame F2, channel C
Hi is used for distribution, and channel CHj is used for addition. That is, a conference call is realized using two call channels in which addition and distribution are performed alternately. The operations of the 111 software associated with this are described in telephones (3a), (3b), (
3C) and (3d) during a meeting will be explained. Each terminal station (2) to (2d) controls the switches 51 to S4 according to FIG.

In frame F1, the contents of channel CHj are input and output to each telephone C3λ) to (3d), and the contents of channel CHj are input.
Add the outputs of the telephones (3a) to (3d) to 4. As a result, a telephone (3a) is placed on the input side of channel CHi of the synchronizer (8).

The addition results of the audio signals (3b), (3C), and (3d) are obtained.

As shown in FIG. 4, the contents of this frame F1 are delayed for a certain period of time by a delay circuit (9) and then output at the timing of frame F2. At this time, the switch S6 is controlled according to FIG. 5, so the above addition result is the synchronizer ff1l+8
+ is output as the contents of channel CHi. on the other hand,
Since the switch S5 is also controlled according to FIG. 5, the contents of the channel CHj output from the synchronizer (8) are cleared. In frame F2, an operation completely opposite to the above is performed. By repeating this process, a conference call is realized.

As described above, according to the present invention, the conference path is realized using two channels that perform addition and distribution alternately, so that shadows due to transmission errors and overflow of addition results occur only during the Rougou tour. This has the effect of preventing deterioration of conference call quality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional conference call system, FIG. 2 is a diagram showing an example of a frame structure of a conference call system according to an embodiment of the present invention, and FIG. 3 is an example of a conference call system according to the present invention. FIG. 4 is a diagram showing an example of the input/output time relationship of the synchronizer, and FIG. 5 is a diagram showing a control method for the switches 5l-s6. CHl -CHn...1st to nth channels, (2a
) ~(2d)...terminal office, (3a)~(3d)...telephone. In the drawings, the same reference numerals indicate the same or equivalent parts. Agent Shin Kuzuno −

Claims (1)

[Claims] (1) In a conference call method comprising a loop-shaped transmission path and a plurality of terminal stations coupled to the loop-shaped transmission path, the conference call is performed using the loop-shaped transmission path in a time division channel multiplexing method. Two channels of the divided call channels are assigned to the conference call, one channel is used as an addition channel for adding up the ^ angle signals from the above terminal stations participating in the conference, and the other channel is used to distribute the added audio signals. A conference call method characterized in that a case where one channel is used as a distribution channel and a case where one channel is used as a distribution channel and the other channel is used as an addition channel are alternately switched.