JPH0252559A - Order-wire branch device - Google Patents

Abstract

PURPOSE:To suppress accumulation of noise due to increase in number of branch connection stations and to prevent deterioration in the quality of voice by connecting a speech line to a transmission line and a reception line of a 4-wire ordering transmission line only when its own station makes a call. CONSTITUTION:A channel selection signal inputted from a transmission line 1 to a synchronizing circuit 3 is given to a synchronizing circuit 13 through a switch 11 as it is since the switch 11 of a branch circuit 4 is thrown normally to the position (a), and outputted to a transmission line 14. Moreover, the selection signal is given to an adder circuit 6, collated with a station number of its own station on a telephone set panel 9 and when they are coincident, a control signal 10 is used to throw the switch 11 to the position (b). Thus, only when its own station applies speech, the speech circuit is connected to the transmission line and the reception line and even if number of branch circuits is increased, noise caused from each station is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a meeting branching device, and more particularly to a meeting branching device used for communication between end stations and branch stations of a four-wire transmission line.

[Conventional technology]

Conventional meeting branching devices include an analog system using a voice band (denoted as VF) and a digital system using a digital transmission path. In the analog method using VF,
Since the level change and distortion increase when branching,
In the case of multiple relays or multiple branches, a digital system is used.

FIG. 2 is a block diagram of an example of a conventional meeting branching device. In FIG. 2, a signal is input from a transmission line 16, passes through a synchronization circuit 18, and enters an adder circuit 20. In the adder 20, the output from C0DEC2B is μm even when there is no call.
Due to the companding side of 4ow or A-ηaW, the linear level does not reach zero, and the noise from the mounting plate 24 is also PCM converted, added, and sent to the transmission line 26.

[Problem to be solved by the invention]

In the above-mentioned conventional branching device for meetings, when there is no call, the input signal of the transmission line 16 and the noise of the tabletop 24 are added and the input signal of the transmission line 2 is added.
6, the communication quality deteriorates in proportion to the number of branch connection stations, and there is also the disadvantage that the DTEF signal being used cannot be identified.

[Means to solve the problem]

The meeting branching device of the present invention includes an adder circuit that outputs a selection signal for channel selection branched from a transmission line and a reception line of a four-wire meeting transmission line, and an adder circuit that outputs a control signal when called by the selection signal. It has a telephone board and a switch that connects the call signal line from the telephone board to the transmitting line and the receiving line only when the control signal is being output.

〔Example〕

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

FIG. 1 is a block diagram of one embodiment of the present invention.

In the present embodiment shown in FIG. 1, a selection signal for channel selection is input from a transmission line 1 to a synchronization circuit 3. Normally, the switch 11 of the branch circuit 4 is connected to the a side, and the input signal is transmitted as it is to the synchronous circuit 13 through the switch 1 and output to the transmission line 14. The selection signal is also input to the adder circuit 6, decoded by the CODEC 8, and input to the telephone board 9.

On the telephone panel 9, the station number of the own station and the number of the received selection signal are compared, and if they match, the switch 11 is switched to side b by the control signal 10, and a ringback tone is sent out, and the telephone Calls can be made by going off-hook.

When the call ends, the on-footer signal from the other party is sent to transmission path 1.
The signal is received by the telephone panel 9 through the synchronization circuit 3, addition circuit 6, and CODEC 8, and when it is confirmed to be an on-hook signal, the switch 11 is switched to the a side by the control signal 10. Calls from the transmission path 15 side are also performed in the same manner as above.

When calling from your own station to the other station, use control signal 1 on the phone.
0, the switching devices 11 and 12 are switched to the b side and a selection signal for calling the partner station is sent out. ju selection multiplication signal C0DEC
One branch is sent to the transmission line 14 through the adder circuit 5, the switch 11, and the synchronization circuit 13, and the other is sent to the transmission line 2 through the adder circuit 7, the switch 12, and the synchronization circuit 3. At the end of the transmitted call, after transmitting an on-footer signal from the telephone fB9, the control signal 10 is used to switch the switch 1],
, 12 to the a side and return to the initial state.

〔Effect of the invention〕

As explained above, the present invention connects the communication circuit to the transmitting line and receiving line of the 4-wire meeting transmission line only when the own station makes a call, so that even if there are many branches connected, the generation from each station can be avoided. This has the effect of preventing deterioration in voice quality since noise can be reduced.

” Yu

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram showing an example of a conventional meeting branching device. 1.2, 14.15... Transmission line, 3, 13... Synchronous circuit, 4... Branch circuit, 5, 6.7... Adder circuit,
8...C0DEC19...Telephone panel, 10...Control signal, 11.12...Switching device.

Claims (1)

[Claims] an adder circuit that outputs a selection signal for channel selection branched from a transmission line and a reception line of a four-wire meeting transmission line; a telephone board that outputs a control signal when called by the selection signal;
A branching device for a meeting, characterized in that it has a switch that connects a call signal line from the telephone board to the transmitting line and the receiving line only when the control signal is being output.