JPH08317359A - Two-way video transmission system - Google Patents

Abstract

PURPOSE: To prevent a line from being disconnected by narrowing band width per channel and increasing the number of channels when congestion is growing. CONSTITUTION: Terminal equipment 31a inside a concentrator 32a and terminal equipment 31j inside a concentrator 32b are mutually connected through a modulator 11, demodulator 7 and video system trunk line 14. Therefore, it is necessary to control the central frequency or output band width of the modulator 11 through a branch line controller 10. In the case of a digital signal, a transmission bit rate is lowered. In order to narrow the output band width, the analog input signal band of the modulator 11 is limited, for example. Then, it is enough only to connect a matrix switch 6 between the terminal equipment 31 inside the same concentrator 32, and the video system trunk line 14 is used for connecting the equipment 31 inside the different concentrators 32. Further, when the congestion of the trunk line 14 is enlarged, the occupied band per line is narrowed and the number of lines is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional video / audio transmission system in which a data LAN is combined with a video / audio dedicated line.

[0002]

2. Description of the Related Art In recent years, a multimedia network capable of transmitting video, audio, and various kinds of data in a vertical and horizontal direction and performing natural communication with a person in a remote place has been in the spotlight. Technically, various digitalized information sources are transmitted using optical fibers, and two-way communication with a destination is performed via an ATM exchange.

At present, although the installation of optical fibers has begun, it is not possible to reach all homes and offices by the year 201.
It will be around 0. Further, it is considered that the ATM switch is still expensive and it will take some time before it becomes popular.

On the other hand, with the rapid spread of personal computers and the like, it has become possible to handle video and audio information relatively easily, and the video can be processed faster than the infrastructure such as the optical fiber or ATM switch is installed. It is expected that the number of users who want to freely exchange voice and voice will increase.

Therefore, it is considered to construct a multimedia network at a low price using the current infrastructure, and a bidirectional system in which a data LAN and a video / audio dedicated line are combined is disclosed in Japanese Patent Laid-Open No. 6-303587. A video / audio transmission system is disclosed.

In the above-mentioned publicly known example, the output of the modulated video / audio terminal is assigned to an empty channel of the same dedicated video / audio line based on an instruction from the channel management workstation, and video and audio are used with a desired partner. It enables two-way communication.

[0007]

However, in the above-mentioned known example, all the video / audio terminals are connected to the same video / audio dedicated line without passing through a gateway or the like, and thus there is a high possibility that the line will be disconnected during congestion. There was a problem with system reliability.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and some video / audio terminals are grouped and each group corresponds to a router or gateway of a data LAN. It has various functional blocks to prevent indiscriminate access to the video / audio dedicated trunk line and to prevent line interruptions due to congestion.

Further, when the congestion becomes large, the bandwidth per channel is narrowed to increase the number of channels to avoid the line interruption.

[0010]

By the above means, it is possible to realize a stable bidirectional video / audio transmission system without line interruption due to congestion.

[0011]

FIG. 1 shows a first embodiment of the present invention.

FIG. 1 is a terminal device 3 including a terminal control device 1, a video (audio) input device 2, and a video (audio) output device 3.
1, a hub for data LAN 4, a router 5, a matrix switch 6, a modulator 11, a demodulator 7, a distributor 8, a combiner 9, and a branch line control device 10, a concentrator 32,
It comprises a data system main line 13, a video (audio) system main line 14, and a main line control device 12.

The terminal control device 1 may be, for example, a personal computer or the like and may be connected to the HUB 4 by Ethernet.
The video (audio) input device 2 is, for example, a video camera or a V camera.
You can use TR etc. The video (audio) output device 3 may be, for example, a cathode ray tube monitor, a television, or a video printer. The matrix switch 6 selects an arbitrary signal from signals applied to a plurality of input terminals (not shown) and outputs it to an arbitrary output terminal (not shown). ) Is connected to the output of the video (audio) input device 2 and the output of the demodulator 7, and the output terminal (not shown) is connected to the input of the video (audio) output device 2 and the input of the modulator 11. The modulator 11 is for modulating the output signal of the video (audio) input device 2, and may be of a modulation system such as AM, SSB, QAM or the like, and the center frequency thereof may be preset so as not to overlap with other modulators. It is set.
The demodulator 7 demodulates a video (audio) signal corresponding to the modulator 11. The output of the video (audio) input device 2 and the input signal format of the video (audio) output device 3 may be, for example, an analog baseband signal conforming to the NTSC system or a digital signal conforming to the MPEG system. . Also, for example, the NTSC system and the MPEG system may coexist. This is because if the matrix switch 6 is configured to perform simple signal switching, the input / output signal format does not particularly matter. Of course, the method is the same as the communication partner. The distributor 8 distributes and supplies the signal on the video (audio) system main line 14 to each demodulator 7, and the synthesizer 9 superimposes the output signal of each modulator 11 on the video (audio) system main line 14. Device.

The branch line control device 10 may be, for example, a personal computer or a workstation, exchanges information with the terminal control device 1 of a plurality of terminal devices 31 connected to the concentrator 32, and controls the matrix switch 6 to cause the concentrator 32 to operate. The arbitrary terminals of the plurality of connected terminal devices 31 are connected. Further, when communicating with a terminal device connected to another concentrator, the branch line control device 10 exchanges information with the main line control device 12 to acquire an empty channel of the video (audio) system main line 14, and then the modulator 7 and the demodulator 11 are acquired. Connect through.

The detailed operation will be described below.

For example, the terminal device 31a and the terminal device 31d
Consider the case of connecting.

First, the terminal control device 1 of the terminal device 31a issues a connection request with the terminal device 31d to the branch line control device 10 via the data system LAN via the HUB 4. The branch line control device 10 determines that the connection is within the concentrator 32a, and confirms the current connection status. To check the connection status, for example, a table showing the usage status of the line as shown in FIG. 2 may be prepared in the branch line control device 10. It should be noted that the usage status of the line here is the connection status of the matrix switch 6.

The branch line control device 10 confirms the connection status, identifies a vacant line, and issues a connection request to the terminal device 31d. If connection is possible, the terminal control device 31d returns a connection permission to the branch line control device 10. The branch line control device 10 to which the connection permission is returned returns the connection permission to the terminal device 31a, and establishes the video and voice lines of the terminal device 31a and the terminal device 31d in the previously confirmed empty line on the matrix switch 6. It should be noted that the video and audio lines of the terminal device 31a and the terminal device 31d have upstream and downstream respectively, and for example, the video (audio) input device 2 and the terminal device 31d of the terminal device 31a.
The video (audio) output device 3 of the terminal device 31a is connected to the uplink, and the video (audio) output device 3 and the terminal device 31d of the terminal device 31a.
The video (audio) input device 2 is connected to the downlink.

Thus, the same concentrator 32a
Inside, it is connected via the matrix switch 6 and is not output to the video (audio) system main line.

Next, consider the case where the terminal device 31a is connected to the terminal device 31j in another concentrator 32b.

First, similarly to the above-mentioned procedure, the terminal control device 1 of the terminal device 31a issues a connection request to the terminal device 31j to the branch line control device 10 via the HUB 4 via the data LAN. The branch line control device 10 determines that the connection is outside the concentrator 32a, checks the usage status of the modulator 11 and the demodulator 7 of the concentrator 32a, identifies an empty system, and issues a connection request to the main line control device 12. . The main line control device 12 is the current video (audio) main line 14
Check the connection status of. Similarly to the above, for confirmation of the connection status of the video (audio) system main line 14, for example, a table showing the use status of the line as shown in FIG. 2 may be prepared in the main line control device 12. It should be noted that the line usage status here is a band usage status of the video (audio) system main line 14.

The trunk line control device 12 confirms the use status, identifies a vacant line, and issues a connection request to the branch line control device 10 of the concentrator 32b. The branch line control device 10 of the concentrator 32b identifies the free system by confirming the connection status by the matrix switch 6 in the concentrator 32b and the usage status of the modulator 11 and the demodulator 7 in the concentrator 32b, and the concentrator 32b.
A connection request is issued to the terminal device 31j in b. If the terminal control device 31j is connectable, the concentrator 32b
A connection permission is returned to the branch line control device 10 inside. The branch line control device 10 to which the connection permission is returned returns a connection permission to the trunk line control device 12, and the concentrator 32b confirmed earlier.
The terminal device 31 is connected to an empty line on the matrix switch 6 in
Connect j's video and audio lines.

The trunk line control device 12 to which the connection permission is returned returns a connection permission to the branch line control device 10 of the concentrator 32a. Concentrator 3 for which connection permission was returned
The branch line control device 10 of 2a returns a connection permission to the terminal device 31a, and connects the video and audio lines of the terminal device 31a to the previously confirmed free line on the matrix switch 6.

In this way, the concentrator 32a
The terminal device 31a therein and the concentrator 32b terminal device 31j are connected to each other via the modulator 11, the demodulator 7 and the video (audio) system main line 14.

Note that the video and audio lines of the terminal device 31a and the terminal device 31j have upstream and downstream, respectively. For example, the video (audio) input device 2 and the terminal device 3 of the terminal device 31a.
1j video (audio) output device 3 is connected to the uplink,
Video (audio) output device 3 of terminal device 31a and terminal device 3
The video (audio) input device 2 of 1j is connected to the downlink.

Thus, different concentrators 32
Between them is connected via the video (audio) system main line 14.

By the way, at the time of connection, the video (audio) system main line 1
When the congestion of 4 further increases, the output bandwidth of the modulator 11 may be narrowed to increase the number of lines. Of course, for that purpose, it is necessary to control the center frequency of the modulator 11 and the output bandwidth through the branch line control device 10.

To narrow the output band width, for example, the analog input signal band of the modulator 11 may be limited. Also,
In the case of a digital signal such as MPEG, the transmission bit rate may be lowered. It is also necessary to change the band of the demodulator 7 according to the band limitation of the modulator 11.

As described above, only the matrix switch 6 needs to be connected between the terminal devices 31 in the same concentrator 32, and the video (audio) system main line 14 is used when the terminal devices 31 belonging to different concentrators 32 are connected.
Further, when the congestion of the video (audio) system main line 14 becomes large, the occupied band per line is narrowed to increase the number of lines, and the possibility of line disconnection due to congestion can be suppressed.

Further, even if a failure occurs in a certain concentrator 32, the branch line control device 10 can be used to disconnect from the video (audio) system main line 14, so that the influence of the failure does not affect other concentrators 32. , The failure of the whole system can be avoided.

Further, the connection between the terminal devices 31 in the same concentrator 32 does not require a modulator / demodulator because it is connected via the matrix switch 6, and the terminal control device 31 can have a simple structure and can be manufactured at a low cost. It is possible.

As described above, it is possible to realize a stable bidirectional video / audio transmission system with less line interruption due to congestion.

A second embodiment of the present invention is shown in FIG.

The feature of this embodiment is that the image (audio) system main line 11 is used.
The bidirectional amplifier 35 is provided in the middle of 4.

When the distance between the concentrators 32 increases, the signal is attenuated, so that the signal is amplified during the process.

Except for the bidirectional amplifying device 35, it is the same as the first embodiment, so detailed description will be omitted.

The bidirectional amplifier 35 is a band selection controller 1
9, band stop circuit 15, band pass circuit 16, amplifier circuit 1
7 and a synthesizer 18.

The band selection control device 19 may be, for example, a workstation or a personal computer. Video (audio) system trunk line 114
Is cut in the middle, and the bidirectional amplifier 35 is inserted into the cut portion.

The operation is as follows.

One of the cut video (audio) system main lines 114 (upper side in FIG. 3) is input to the band stop circuit 15a and the band pass circuit 16a. The stop and pass frequency bands of the band stop circuit 15a and the band pass circuit 16a are set to be the same. The output of the band pass circuit 16a is an amplifier 17a.
And the signal in the pass band is amplified. Amplifier 17
a may be, for example, a wide band amplifier having a constant amplification gain with respect to the pass frequency band of the band pass circuit 16a.
The output of the amplifier 17a is combined with the output of the band rejection circuit 15a by the combiner 18a and output to the other disconnected video (audio) system main line 114 (lower side in FIG. 3).
Similarly, the other disconnected video (audio) system main line 114 (lower side in FIG. 3) is input to the band stop circuit 15b and the band pass circuit 16b, and the output of the band pass circuit 16b is input to the amplifier 17b. The band stop circuit 15 by the combiner 18b.
It is combined with the output of b. The output of the synthesizer 18b is output to the other disconnected video (audio) system main line 114 (upper side in FIG. 3).

In this way, it is possible to selectively amplify a signal in a specific band in both the up and down directions.

On the other hand, the band stop circuit 15 and the band pass circuit 1
The stop and pass frequency bands of 6 are variable and are set by the band selection control device 19.

The band selection control device 19 is the trunk line control device 12
Information is exchanged with each other, the line (band) in which the signal level decreases due to a long distance is determined, and the signal level of the line (band) specified by both the up and down lines is amplified by the method.

These states are shown in FIGS. 4 and 5. It can be seen that the signal levels of the selected bands are amplified for the downlink and the uplink respectively.

In the description, the band to be amplified is expressed as one line, but a plurality of lines may be amplified in the same way. In that case, the band stop circuit 15 and the band pass circuit 16 may be set to the desired band as the band pass band and the band pass circuit 16 via the band selection control device 19. Further, a plurality of band stop circuits 15 and band pass circuits 16 may be arranged for each of the upstream and the downstream.

As described above, the video (audio) system main line 1
Even if the distance of 14 becomes long, stable two-way communication can be performed without line interruption due to signal attenuation.

A third embodiment of the present invention is shown in FIG.

In FIG. 6, the site 40a and the site 40b are connected via the public network 21. The structure of the site 40 is almost the same as that of the first embodiment, except that the ISDN terminal device 20, for example, is provided for connecting to the public network.

The ISDN terminal device 20 is connected to the concentrator 32b, and when viewed from the concentrator 32b, it may have the same input / output format as the terminal device 31.

By doing so, the ISDN terminal device 20 can be connected from the terminal device 31a, for example, as in the first embodiment. Here, at the site 40b as well, the terminal device 31a and the ISDN terminal device 20 are connected in advance, and the ISDN terminal device 20 at the site 40a and the ISDN terminal device at the site 40b are connected.
If the DN terminal device 20 is connected to the public network 21, the site 4
0a terminal device 31a and site 40b terminal device 31a
Can be connected.

For example, if the site 40 is one building, the buildings can be connected. Even in that case, existing infrastructure may be used in each site or building.

As described above, according to the present invention, it is possible to cope with the infrastructure such as optical fiber and ATM switch which are spread from the trunk line of the public network, and it is possible to realize a realistic video / audio bidirectional transmission system.

In the above description, the terminal device 31 is configured to have both video (audio) input and output, but it may be configured to have only video (audio) input or output.

Further, not only one-to-one communication but also one-to-many, n-to-n, etc. are possible in a broadcast image.

[0055]

According to the present invention, it is possible to realize a stable bidirectional video / audio transmission system with less line interruption due to congestion.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment.

FIG. 2 is an explanatory diagram of a line table of a branch line control device 10 and a trunk line control device 12.

FIG. 3 is an explanatory diagram of a second embodiment.

FIG. 4 is an explanatory diagram of the operation of the bidirectional amplifier 35.

FIG. 5 is an explanatory diagram of the operation of the bidirectional amplifier 35.

FIG. 6 is an explanatory diagram of a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Terminal control device, 2 ... Video input device, 3 ... Video output device, 4 ... HUB, 5 ... Router, 6 ... Matrix switch, 7 ... Demodulator, 8 ... Distributor, 9, 18 ... Combiner, 10 ... Branch line control device, 11 ... Modulator, 12 ... Trunk line control device, 13 ... Data system trunk line, 14 ... Image system trunk line, 31 ... Terminal device, 32 ... Concentrator.

Claims (4)

[Claims] 1. A first set of a plurality of terminal devices for inputting and / or outputting a video and / or audio signal and for inputting and outputting a connection request and connection permission information, and an input / output signal line of the plurality of terminal devices. An integrated set distribution device for collecting and connecting the input / output lines of the connection request and connection permission information, and an input signal line for inputting and / or outputting the video and / or audio signal, And / or a second collective distribution device that collectively distributes the output signal lines,
A branch line control device that is connected to the first collective distribution device and manages the collective distribution status of the second collective distribution device and performs collective distribution control, wherein the first collective distribution device is a data system via a barrier device. The first integrated distribution device connected to a signal main line, the second collective distribution device connected to a video and / or audio system signal main line via a modulator / demodulator, and the data system signal main line; And / or bidirectional video transmission comprising a trunk line control device for managing the line connection status of the voice signal trunk line, and the nth integrated distribution device connected to the data signal trunk line and the video and / or voice signal trunk line In the system, if video and / or audio information is transmitted only between the plurality of terminal devices connected to the first integrated collective distribution device, the second collective distribution device is used. Said plurality of terminal devices interconnected,
When transmitting video and / or audio information between the terminal devices connected to the first integrated distribution device and the nth integrated distribution device, the second collective distribution device and the modulator / demodulator A bidirectional video transmission system, characterized in that the terminal devices are interconnected via the video and / or audio signal trunk lines. 2. The video and / or audio signal trunk line according to claim 1, when the video and / or audio system signal line is congested.
Alternatively, a bidirectional video transmission system that increases the total number of lines by narrowing the occupied bandwidth per line for audio signal trunk lines. 3. The bidirectional video transmission system according to claim 1, wherein a bidirectional amplifier is provided in the middle of the video and / or audio system signal trunk line. 4. The bidirectional video transmission system according to claim 1, wherein the bidirectional video transmission system is provided with an ISDN terminal device and is connected to a bidirectional video transmission system provided with a corresponding ISDN terminal device via a public network.