JPH0263364A - Voice n:n communication system in loop type digital transmission line - Google Patents

Abstract

PURPOSE:To constitute the N:N communication, that is, voice conference or ordering line communication even in a loop type transmission line by adding two echo cancelling circuits and a digital adder circuit. CONSTITUTION:An echo resulting from a voice digital data generated at an input/output section of its own station to a loop transmission line 1 while a delay in the loop transmission line 1 takes place and returning to its own station is cancelled by echo cancelling circuits 2, 5 and a voice digital data from other station is outputted. Then the voice digital data and a voice digital data sent from its own station are added and outputted by a digital adder means 6. Thus, the circulating transmission of the data sent from its own station provided to the loop transmission line 1 is blocked. Thus, the talking between plural stations is attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to voice communication in a digitalized loop-type transmission line, and in particular to an N:N system that allows conversations to be held simultaneously in several locations such as an audio conference or a meeting line. Regarding communication methods.

[Conventional technology]

Conventionally, in this type of voice N:N communication system, any one station was the source, and when transmitting, other stations could only receive, and when the transmission from that source was finished. Even in N:N communication, where a new K or another station becomes the source,
During a call, a breath talk system was used that temporarily established a 1:N communication configuration.

[Problem to be solved by the invention]

In the conventional voice N:N communication system described above, the master station is determined at one point, and the communication status is one-way p, l:N. The disadvantage is that other stations cannot transmit at the same time (when the station is transmitting).

[Means to solve the problem]

In the audio N:N communication system in a loop-type digital transmission line according to the present invention, audio digital data generated at the own station at the input/output section to the loop transmission line is transmitted to the own station with a delay occurring on the loop transmission line. The sound digital data from the other station is output after the echo when it returns is canceled by the canceling means, and the voice digital data and the transmitted voice digital data from the own station are added together by the digital adding means and then output. It is something.

[For production]

The present invention makes it possible to simultaneously communicate with multiple parties by preventing circular transmission of the data sent out from the own station by the loop-type transmission line.

〔Example〕

The figure is a block diagram showing an embodiment of a voice N:N communication system in a loop-type digital transmission line according to the present invention, and shows a part of the transmission line and terminal interface of each station (node) connected to the loop-type transmission line. Configure. In the figure, 1 is a loop transmission path through which audio data S1 transmitted from the local station is transmitted and received data S2 with a propagation delay T is returned to the local station, and 2 is a loop transmission path 1 with a propagation delay T. From the received data S that has occurred and returned to the local station in a friendly state, the echoes that are the local station transmission data that were output before this propagation delay T are erased, and the output data S3, that is, the other data on the transmission path 1, is An echo canceling circuit 3 outputs the audio digital data from the station, and converts this output data S8 from analog to analog to output an analog signal S to the receiving terminal, and transmits data S from the actual terminal (not shown). The echo S due to the analog signal S by the hybrid circuit shown below
, C (±, N is), attenuation due to passing through the hybrid circuit) is added to the signal S 4//1'J+ S B
A converts 〜 and outputs digital data S6
/D/D/A conversion circuit, 4 is a hybrid circuit consisting of a 2W/4W conversion circuit, 5 is digital data S, and the hybrid circuit 4 eliminates the echo caused by the analog signal S going around, and outputs data. 6 is an echo cancellation circuit that outputs audio data S8 from another station on the transmission path, and output data S8 that is audio digital data transmitted from the own station, and outputs the result as audio data Sl. This is an adder circuit.

Next, the operation of the voice N:N communication system in the loop digital transmission line with the above configuration will be explained. first,
The audio data Sl transmitted from the local station is transmitted through the loop transmission path 1 and returns to the local station as received data S2 with a propagation delay T. Therefore, when trying to configure an audio conference or meeting line, due to the unique topology of a loop, the audio data output from one station on this transmission path must be removed from the transmission path somewhere. , the data is forever transmitted on the loop transmission line 1 and remains as an echo of the voice. Therefore, the echo cancellation circuit 1 erases the own station transmission data output before the propagation delay T from the received data S8, and outputs the output data S8. This output data S3 has the transmission data from the own station erased, and becomes only the synthesized data (added data) of audio data from other stations on the transmission path 1. Then, the A/D/D/A conversion circuit 3 outputs this output data S8.
That is, it is possible to D/A convert audio digital data from another station on the transmission path 1 and output an analog signal S to the receiving terminal.

On the other hand, transmission data S from an actual terminal (not shown).

is A/D converted by the A/D-D/A conversion circuit 3 via the hybrid circuit 4 and outputs digital data S. At this time, echoes S, /N caused by the analog signal S4 generated by the hybrid circuit 4 are also input to this digital data S6, and are A/D converted and superimposed, but these echoes S, /N are canceled by the echo cancellation circuit 5 and output data S, t-. Then, the adder circuit 6 adds the output signal S8, which is the audio digital data from another station on the transmission path, and the output data S, which is the audio digital data transmitted from the own station, to obtain the audio data S1.
It is output to transmission path 1 as Therefore, each station can delete the data it transmitted from the received data, listen to the synthesized components of audio data from other stations, and can also participate in the call at any time.

〔Effect of the invention〕

As explained above in detail, according to the voice N:N communication system in the loop type digital transmission line according to the present invention,
By adding two echo canceling circuits and one digital adder circuit, it is possible to configure N:N communication and voice conference and meeting lines even on a loop type transmission line. .

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of a voice N:N communication system in a loop type digital transmission line according to the present invention. 1...Transmission line, 2...Echo cancellation circuit, 3...
- A/D-D/A conversion circuit, 4...hybrid circuit, 5...echo cancellation circuit, 6...addition circuit.

Claims (1)

[Claims] In a digitized loop-type transmission line, the echo when the audio digital data generated at the own station returns to the own station with a delay on the loop transmission line at the input/output section to this transmission line is eliminated. an adder circuit that digitally adds the audio digital data from another station and the audio digital data transmitted from the own station in a state in which the echo of the own station has been canceled by the echo canceling circuit; A voice N:N communication system in a loop type digital transmission line, characterized by comprising an echo canceling circuit for canceling echoes caused by looping from a hybrid circuit after being converted into an analog signal by a D conversion circuit.