JPH08279997A - Two-way catv system - Google Patents

Abstract

PURPOSE: To improve response of a service even if a wide frequency band is not used by setting up mutually independent two-way communication channels on the upstream side and the downstream side by the use of a sub-information station arranged on the way of a communication line. CONSTITUTION: At least one sub-information station is arranged on the way of a communication line. The sub-information station includes a 1st two-way communication channel for executing two-way information service communication only with the upstream direction in an UP signal frequency band and sets up a 2nd two-way communication channel for executing two-way information service communication only with the downstream side in a DOWN signal frequency band. In this case, a 1st channel signal and a 2nd channel signal are mutually independently band-stopped by respective band rejection filters 45, 48 so as not to be leaked respectively to the downstream side and the upstream side. Information data obtained through the 1st and 2nd channels are stored in a storage means 63 in the sub-information station so as to be shared and necessary information are properly supplied in accordance with a request from the upstream side or the downstream side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-way CATV system capable of effectively using channels and realizing a two-way information service for a large number of subscribers together with multi-channel broadcasting.

[0002]

2. Description of the Related Art In a two-way CATV system, a frequency division type communication system is adopted.
Bidirectional transmission is performed by using a frequency band of 6 to 50 MHz for upstream signals and a frequency band of 70 to 450 MHz for downstream signals. However, in the frequency band for upstream signals, 24 to 30 MHz, 30 to 36 MHz, and 36 to 42 can be used for video services and high-speed digital communication due to the problem of transmission quality due to noise and the like.
Only the band corresponding to 3 TV channels of MHz. In the currently used CATV station, 1 to 2 TV channels are already used for relaying, so that the frequency that can be newly used is 1T.
Only about V channels. On the other hand, regarding the frequency band for the downlink signal, it is possible to use a plurality of TV channels for information services and the like.
Often below the channel.

[0003]

By the way, in recent years, interactive information services for subscribers using the interactive CATV system have become widespread. This type of information service has a configuration in which bidirectional data transmission is performed between an information providing device installed in a CATV center and each subscriber terminal device. It is possible to secure frequencies for one TV channel for upstream information to the CATV center and only for several channels for downstream information. Therefore, it is difficult to provide a sufficient information service to a large number of subscriber terminal devices, such as a limited number of subscriber terminal devices that can use this information service at the same time and poor responsiveness. Have

In order to solve this problem, it has been considered to secure a sufficient channel for upstream information by widening the frequency band for upstream signals. According to this method, the transmission is performed in the case of an existing CATV facility. Another problem arises in that it is necessary to replace the bidirectional CATV amplifier and the CATV viewing device for subscribers inserted in the route, and the cost burden thereof becomes considerable.

Further, in Japanese Patent Laid-Open No. 4-16089,
A configuration has been proposed in which the frequency band for upstream signals is widened only on the trunk line and the normal band is converted for the branch line, thereby eliminating the need to replace the subscriber device. However, even with this proposed configuration, the equipment of the trunk system must be changed, and only one TV channel can be secured in the branch line system, and the restriction of the branch line system similarly occurs. Have a point.

An object of the present invention is to provide a bidirectional CA capable of realizing a bidirectional information service for a large number of subscribers without reducing the frequency for TV broadcasting service.
To provide a TV system.

Another object of the present invention is to make it possible to secure the line capacity required for the interactive information service performed in the interactive CATV system without reducing the frequency for the TV broadcasting service. To provide a connection device.

[Means for Solving the Problems]

A feature of the present invention for solving the above problems is that a CATV center provided with an information providing device and a large number of subscriber terminal devices are connected by a communication line.
Bidirectional communication for the TV broadcasting service and various interactive information services is performed between the CATV center and the subscriber terminal device by using the frequency band for the up signal and the frequency band for the down signal set by the frequency division method. In the two-way CATV system configured as described above, at least one sub information station for information service is provided in the middle of the communication line, and two-way information service communication is performed only in the upstream direction of the sub information station. The first two-way communication channel and the second two-way communication channel for performing two-way information service communication only in the downstream direction of the sub-information station using the upstream signal frequency band and the downstream signal frequency band. The information data obtained through the first bidirectional communication channel and the information data obtained through the second bidirectional communication channel. In point so as to share in the sub-information station.

The first bidirectional communication channel has a predetermined upstream signal frequency band and a predetermined downstream signal frequency band.
It can be configured by providing respective upstream dedicated frequency bands for information services. In this case, by using an appropriate frequency selection member (for example, band rejection filter means) so that the signal of the upstream dedicated frequency band provided in the downlink signal frequency band is not transmitted to the downstream side, the first both The destination communication channel can be provided independently of the second bidirectional communication channel.

On the other hand, the second bidirectional communication channel is set in the predetermined upstream signal frequency band and the predetermined downstream signal frequency band, either in the same frequency band as the upstream dedicated frequency band or in an arbitrary other than the same frequency band. The downstream dedicated frequency band for the information service of the specified frequency band can be provided and configured. In this case, an appropriate frequency selection member (for example, band elimination filter means) should be used to prevent the signal in the downstream dedicated frequency band provided in the upstream signal frequency band from being transmitted to the upstream side. Thus, the second bidirectional communication channel can be provided independently of the first bidirectional communication channel.

The information on the upstream side and the information on the downstream side can be collectively managed by the sub-information station, and necessary information is stored and shared in an appropriate storage means of the sub-information station. Therefore, the information service can be provided by appropriately supplying necessary information data in response to a request from the upstream side or the downstream side.

On the other hand, another feature of the present invention is that a CATV center provided with an information providing device and a large number of subscriber terminal devices are connected by a communication line, and the CATV center and the subscriber terminal devices are connected to each other. A bidirectional C configured such that bidirectional communication for TV broadcasting service and various bidirectional information services is performed using an up signal frequency band and a down signal frequency band set by a frequency division method.
A connection device for setting two mutually independent two-way communication channels for information service in an ATV system, the signal being in a predetermined first dedicated frequency band provided in the upstream signal frequency band. Means for blocking the passage of a signal of a predetermined second dedicated frequency band provided in the frequency band for the downlink signal, and an output of the first means Side and an input side of the second means for communicating with an upstream side using the first dedicated frequency band and the second dedicated frequency band.
A second means for communicating with a downstream side, which is connected to a communication means and an input side of the second means and an output side of the first means, and uses the first dedicated frequency band and the second dedicated frequency band. And a communication means.

[0013]

In the upstream direction from the sub-information station, bidirectional information service communication can be performed with the sub-information station through the bidirectional communication channel. This first bidirectional communication channel is for performing bidirectional information service communication only with the upstream direction, and the information flowing through the first bidirectional communication channel does not flow through the second bidirectional communication channel as it is.

On the other hand, in the downstream direction from the sub information station, bidirectional information service communication can be performed with the sub information station through the second bidirectional communication channel. This second bidirectional communication channel is for performing bidirectional information service communication only with the downstream direction, and the information flowing through the second bidirectional communication channel does not flow through the first bidirectional communication channel as it is.

As described above, two mutually independent bidirectional communication channels are provided on the upstream side and the downstream side of the sub-information station, so that even if the same frequency is assigned to these two bidirectional communication channels. There is no problem.

Further, since each information flowing in the first and second bidirectional communication channels is shared by the sub-information stations, the same information can be provided to any bidirectional communication channel.

According to another feature of the present invention, the first dedicated frequency band provided in the frequency band for the upstream signal and the second dedicated frequency band provided in the frequency band for the downstream signal are used for the downstream direction. The interactive information service for the is carried out using the first communication means. The contents of the two-way information service for the downlink direction are not sent in the upstream direction by the first and second means, and therefore, the upstream side independently uses these first and second dedicated frequency bands for another purpose. Can be used. That is, on the upstream side, another two-way information service for the upstream direction is performed using the second communication means using the first and second dedicated frequency bands.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a system configuration diagram showing an embodiment of an interactive CATV system according to the present invention. The interactive CATV system 1 shown in the figure includes a CATV center 2 and a CA
It has a large number of subscriber terminal devices connected to the TV center 2 via a communication cable 3. In FIG. 1, only three of the subscriber terminal devices 4A, 4B, 4C are shown.

The CATV center 2 has a CATV broadcasting device 5 for TV broadcasting service and an information providing device 6 for interactive information service. The CATV broadcasting device 5 and the information providing device 6 are heads. It is connected to the communication cable 3 via the end 7, whereby each subscriber terminal device 4
Two-way communication for a predetermined service is performed with respect to A, 4B, and 4C.

In this bidirectional communication, the frequency band for upstream signals of 6 to 50 MHz set by the frequency division method and 7
It is performed using the frequency band for downlink signals of 0 to 450 MHz. However, this frequency allocation is an example, and it is needless to say that any other frequency allocation may be adopted without being limited to this.

Next, the structure of the communication path system 30 constructed by using the communication cable 3 will be described. In FIG. 1, 31A to 31E are connectors for connecting a subscriber terminal device to the communication cable 3, and 33A and 33B are relay amplifiers. Since these respective members are publicly known, detailed description thereof will be omitted.

Data communication for a two-way information service to be transmitted through the communication path system 30 is performed by the communication path system 30.
Sub-information stations 32A, 32B, and 32C are provided in the middle of the communication cable 3 in order to efficiently perform them. These sub information stations 32A, 32B, 32C
Both have a function for establishing mutually independent bidirectional communication channels on the upstream side and the downstream side,
The communication path system 30 includes these sub information stations 32A, 32B,
It is divided into the following four blocks by 32C. (1) The first block B1 between the CATV center 2 and the sub information stations 32A and 32C. (2) The second block B2 between the sub information station 32A and the sub information station 32B. (3) The third block B3 downstream of the sub information station 32B. (4) The fourth block B4 downstream of the sub information station 32C.

In each of the first block B1 to the fourth block B4, the first to fourth bidirectional communication channels for bidirectional information service communication are set as mutually independent bidirectional communication channels as described later. Has been done.

The embodiment shown in FIG. 1 shows an example in which the communication path system 30 is divided into four blocks by providing four sub-information stations, but this is an example. One or more sub-information stations can be provided in an appropriate number, and may be divided into two or more arbitrary blocks.

FIG. 2 is a detailed block diagram of the sub information station 32A. Reference numeral 40 denotes a connecting device which is connected in the middle of the communication cable 3 and sets two mutually independent bidirectional communication channels in the communication path system 30. In the connection device 40, 41 is an upstream connection terminal of the communication cable 3, 42 is a downstream connection terminal of the communication cable 3, 43 is a band distribution combiner having a combined output terminal 43A connected to the upstream connection terminal 41, 44 is a composite output terminal 44A connected to the downstream side connection terminal 42.
Is a band division synthesizer having.

A first filter 45 and an amplifier 46 are connected between the output terminal 44B of the band distribution synthesizer 44 and the input terminal 43C of the band distribution synthesizer 43 as shown in the drawing, and the output terminal 43B of the band distribution synthesizer 43. Between the input terminal 44C of the band distribution / combiner 44 and the amplifier 47 and the second filter 4
And 8 are connected as shown. 49 is an output terminal 44
Downstream output terminal connected to B, 50 is input terminal 44C
Is an upstream input terminal connected to the output of the amplifier 47, and 52 is an upstream input terminal connected to the input of the amplifier 46.

Reference numeral 60 denotes an information providing device for performing data communication for a two-way information service using the two two-way communication channels set by the connection device 40 described above.

The information providing device 60 has an upstream output terminal 51.
And the upstream side connection terminal 41 connected to the upstream side input terminal 52.
A first interface device 61 for performing communication for two-way information service with each device in the first block B1 connected to the downstream side output terminal 49 and the downstream side input terminal 50 It has a second interface device 62 for performing communication for two-way information service between each device in the second block B2 connected to the side connection terminal 42.

The first interface device 61 and the second interface device 62 are connected to the control device 64 connected to the information storage device 63, and need data for information services stored in the information storage device 63. It can be supplied upstream or downstream accordingly. The details of the two bidirectional communication channels for supplying this data will be described below.

FIG. 3 is a frequency arrangement diagram of signals flowing in the communication cable 3. The upstream signal is arranged in the upstream signal frequency band B1 already described, and the downstream signal frequency band B is arranged.
Downlink signals are assigned to the second channel. And, in the frequency band for upstream signal B1, a first dedicated frequency band BU used only for communication for information service is provided,
Uplink information data is transmitted using the first dedicated frequency band BU. Similarly, in the downlink signal frequency band B2, the second dedicated frequency band BD used only for communication for information service is provided, and the downlink information data is used by using the second dedicated frequency band BD. Is transmitted.

First, the downstream signal will be described. Of the signals flowing in the upstream communication cable 3, the upstream downstream signal S2 is separated from the upstream upstream signal S1 by the band distribution synthesizer 43, and its output terminal 43B is provided. Therefore, only the upstream downlink signal S2 is output. This upstream downlink signal S2
As shown in FIG. 4A, the upstream downlink data signal D1 for the information service on the upstream side is arranged in the second dedicated frequency band BD. The upstream down signal S2 is amplified by the amplifier 47, then taken out from the upstream output terminal 51 as it is, and input to the first interface device 61. An upstream downlink data signal D1 for information service data from the upstream side is included in the second dedicated frequency band BD of the downlink signal S2, and the upstream downlink data signal D1 is the first interface device. Received by 61.

The output from the amplifier 47 is also input to the second filter 48. The second filter 48 is configured as a band stop filter that blocks the passage of the frequency component of the second dedicated frequency band BD of the upstream downlink signal S2. Therefore, from the second filter 48, FIG. , The common downlink signal S2C from which the frequency component of the second dedicated frequency band BD has been removed from the downlink signal frequency band B2 is output, and the band distribution combiner 4
4 input terminal 44C. Due to the above-described function of the second filter 48, the upstream downlink data signal D1 is not supplied to the downstream side.

At the input terminal 44C, the downstream downlink data signal D2 using the frequency within the second dedicated frequency band BD having the data for the information service to be transmitted from the second interface device 62 to the downstream side is provided. Is being supplied. Therefore, the combined output terminal 4 of the band distribution combiner 44 is
From 4A, the downstream communication cable 3 is supplied with a downstream downlink signal S2 ', which is formed by adding the downstream downlink data signal D2 to the common downlink signal S2C (see (C) in FIG. 4).

As described above, among the downlink signals, the common downlink signal S2C is not processed by the sub information station 32A at all,
As it is, it flows commonly to the upstream side and the downstream side. However, the content of the data sent by using the second dedicated frequency band BD can be independently determined separately for the upstream side and the downstream side.

Next, the upstream signal will be described with reference to FIG. Of the signals flowing in the communication cable 3 on the downstream side, the downstream upstream signal S1 ′ is separated from the downstream downstream signal S2 ′ by the band distribution synthesizer 44 and its output terminal 44B.
Only the downstream upstream signal S1 'is output from. As shown in FIG. 5A, the downstream upstream signal S1 ′ has a downstream upstream data signal U2 for downstream information service arranged in the first dedicated frequency band BU. The downstream upstream signal S1 ′ is supplied to the second interface device 62 as it is, and also the input terminal 43C of the band distribution / combining device 43 via the first filter 45 and the amplifier 46.
Is input to

The first filter 45 has a downstream upstream signal S1 '.
Of the first dedicated frequency band BU is configured as a band stop filter that blocks passage of frequency components, and therefore, as shown in FIG. Common upstream signal S from which the frequency component of the first dedicated frequency band BU has been removed from the band B1
1C will be output. Due to the above operation of the first filter 45, the downstream upstream data signal U2 is not supplied to the upstream side, that is, the band distribution / combiner 43.

At the input side of the amplifier 46, an upstream upstream data signal using a frequency within a first dedicated frequency band BU containing data for information service to be sent upstream from the first interface device 61. U1 is supplied. Therefore, the first terminal 4 of the band divider / combiner 43 is
3A supplies upstream upstream signal S1 obtained by adding upstream upstream data signal U1 to common upstream signal S1C to upstream communication cable 3 (see FIG. 5C).

As described above, among the upstream signals, the common upstream signal S1C is not processed by the sub-information station 32A, and flows as it is to the upstream side and the downstream side. However, the content of the data sent by using the first dedicated frequency band BU can be independently determined separately for the upstream side and the downstream side.

From the above description, this CATV system 1
In the above, a first two-way communication channel for information services, which uses only the first dedicated frequency band BU and the second dedicated frequency band BD and is capable of two-way communication only with the upstream side, is provided on the upstream side of the sub-information station 32A. With the same second on the downstream side
A two-way communication channel can be provided and these two
It is understood that the independence of the two bidirectional communication channels can be maintained.

However, the first interface device 61 and the second interface device 62 are the same as the information storage device 63.
Since the control device 64 and the control device 64 are commonly used, the information data to be handled is common, and requests for information data from the upstream side and the downstream side can be dealt with without distinction between upstream and downstream. Further, the requested information data is the information storage device 63.
If not, then more information can be requested from upstream or downstream.

In the above description, one sub information station 32A has been described in detail, but the other sub information stations 32B and 32C have the same configuration, and therefore description thereof will be omitted. From the above description, in the third block B3, the third bidirectional communication channel is similarly provided by the sub information station 32B, and in the fourth block B4, the fourth bidirectional communication channel is similarly provided by the sub information station 32C. Understand.

The sub-information stations 32A and 32 are connected to the communication cable 3.
By arranging B and 32C, the first block B1 to the fourth block B4 divided by the B and 32C are independently operated using the first dedicated frequency band BU and the second dedicated frequency band BD. Since the first to fourth bidirectional communication channels which can be performed are established, the information services can be separated by utilizing the sub information stations 32A, 32B and 32C. Therefore, the number of subscriber terminal devices handled by one device provided for providing information is reduced, and the responsiveness of services is improved without using a wide frequency band. In addition, since the number of subscriber terminal devices handled is small, the cost of the sub-information station is low, and the impact in the event of a failure is within a limited range. There is no.

Furthermore, it is possible to add the information providing device by inserting the connecting device without changing the existing amplifier, the viewing device, and the other bidirectional device of the CATV network.

Therefore, even if the number of subscribers is small at the beginning, the information providing apparatus is installed by the number corresponding to the number of subscribers, and then the information providing apparatus is added by simply inserting the connecting device in an appropriate place as the number of target subscribers increases. You can
It becomes possible to support a large number of subscribers.

The present invention is not limited to the configuration of the above-described embodiment. For example, (1) the downlink information channel to the information providing device is set in another band and directly sent from the CATV center to each information providing device, or each information providing device obtains information through a telephone line or the like. You may. (2) Also, for the subscriber terminal device, C
The downlink information may be sent from the information providing device of the ATV center using another band. (3) Since the transmission path does not depend on the physical medium, an optical fiber or the like may be used.
(4) In addition, various modifications may be implemented.

Further, the service using the interactive CATV system according to the present invention is not limited to the above-mentioned embodiment, and the following services are possible. (1) Information search service by subscribers. (2) Information exchange between subscribers. (3) Video services such as video on demand. (4) Data service for karaoke on demand, news on demand, etc. (5) Other unidirectional and bidirectional data communication services for various terminal devices installed on the CATV network.

[0048]

According to the present invention, the sub information station provided in the middle of the communication line sets mutually independent bidirectional communication channels on the upstream side and the downstream side, whereby the upstream side and the downstream side are set up. Since the information services are separated from each other, the number of subscriber terminal devices handled by one device provided for providing information is reduced, and the responsiveness of the service is achieved without using a wide frequency band. Is improved.
In addition, since the number of subscriber terminal devices handled is small, the cost of the sub-information station is low, and the impact in the event of a failure is within a limited range. There is no.

Furthermore, it is possible to add the information providing device by merely inserting the connecting device without changing the existing amplifier, the viewing device, the other bidirectional device, etc. of the CATV network. Therefore, even if the number of subscribers is small at the beginning, install the information providing devices by the number corresponding to the number of subscribers, and then add the information providing devices by simply inserting the connection device at an appropriate place as the number of target subscribers increases. It is possible to handle a large number of subscribers.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an embodiment of a bidirectional CATV system according to the present invention.

FIG. 2 is a detailed block diagram showing the configuration of a sub-information station shown in FIG.

FIG. 3 is a frequency layout diagram of signals flowing in the communication cable of FIG.

4 is an explanatory diagram for explaining a state of a downlink signal in a first bidirectional communication channel and a second bidirectional communication channel provided on the upstream side and the downstream side by the connection device shown in FIG.

5 is an explanatory diagram for explaining a state of an upstream signal in a first bidirectional communication channel and a second bidirectional communication channel provided on the upstream side and the downstream side by the connection device shown in FIG.

[Explanation of symbols]

 1 bidirectional CATV system 2 CATV center 3 communication cables 4A, 4B, subscriber terminal device 5 CATV broadcasting device 6 information providing device 7 headend 30 communication path system 32A, 32B, 32C sub information station 40 connection device 43, 44 band distribution Combiner 45 First filter 48 Second filter 60 Information providing device BU First dedicated frequency band BD Second dedicated frequency band B1 Upstream signal frequency band B2 Downstream signal frequency band D1 Upstream downstream data signal D2 Downstream downstream data signal S1 upstream upstream signal S1 'downstream upstream signal S1C common upstream signal S2 upstream downstream signal S2C common downstream signal S2' downstream downstream signal U1 upstream upstream data signal U2 downstream upstream data signal

Claims (2)

[Claims] 1. A CATV provided with an information providing device.
The center and a large number of subscriber terminal devices are connected to each other by a communication line, and there is a T between the CATV center and the subscriber terminal devices.
In a bidirectional CATV system configured to perform bidirectional communication for V-broadcasting service and various bidirectional information services using an up signal frequency band and a down signal frequency band set by a frequency division method. , At least one sub-information station for information service is provided in the middle of the communication line, and a first two-way communication channel for performing two-way information service communication only with the upstream direction of the sub-information station and the sub-information A second bidirectional communication channel for performing bidirectional information service communication only with the downstream direction of the station is provided using the frequency band for the up signal and the frequency band for the down signal, and through the first bidirectional communication channel. The sub information station may share the obtained information data and the information data obtained through the second two-way communication channel. An interactive CATV system characterized by: 2. A CATV provided with an information providing device.
The center and a large number of subscriber terminal devices are connected to each other by a communication line, and there is a T between the CATV center and the subscriber terminal devices.
In a bidirectional CATV system configured such that bidirectional communication for V-broadcasting service and various bidirectional information services is performed using an up signal frequency band and a down signal frequency band set by a frequency division method. A connection device for setting two mutually independent two-way communication channels for information service, which is capable of passing a signal of a predetermined first dedicated frequency band provided in the frequency band for upstream signals. First means for blocking; second means for blocking passage of a signal in a predetermined second dedicated frequency band provided in the frequency band for downlink signals; output side of the first means; First communication means connected to the input side of the second means for communicating with the upstream side using the first dedicated frequency band and the second dedicated frequency band; and the input side of the second means and the A connection device comprising: second communication means connected to the output side of the first means for communicating with the downstream side using the first dedicated frequency band and the second dedicated frequency band. .