JPS63206077A - Two way catv system - Google Patents

Abstract

PURPOSE:To eliminate a tap-off a leading wire by providing an MCA slave station communication equipment at a transmission line in branch line and constituting the transmission line line in branch line at a terminal side of a leakage coaxial cable from the MCA slave station communication device. CONSTITUTION:A center 1 and a terminal 2 are connected through a trunk line coaxial cable 3, a two way amplifier 4, a branch line coaxial cable 5, an MCA slave station communication equipment 6 and a leakage coaxial cable (LCX) 7. In the terminal 2, for example, a key pad, a television, a speaker, etc., connected to an industrial television camera and a home terminal are included. Here, since the system is constituted by using an LCX instead of a coaxial cable for the transmission line in branch line, the rise image of the industrial television camera can be sent by radio and the ordinary system ca be used by receiving the leakage electric wave from the television, radio and LCX.

Description

[Detailed Description of the Invention] Overview In a bidirectional CATV system, an MCA is used in a branch transmission line.
The present invention is characterized in that a slave station communication device is provided and a leaky coaxial cable is used in the branch line transmission line on the terminal side from the station communication device to the MC8.

By using a leaky coaxial cable instead of a regular coaxial cable in the branch line system, there is no need for tap-offs or drop-in lines, and there is no need to install lead-in work to the subscriber's home. At the same time, since televisions and home terminals use wireless technology, it can also be applied to mobile devices.

INDUSTRIAL APPLICATION FIELD The present invention relates to a two-way CATV system, and more particularly to a two-way CATV system using a leaky coaxial cable in a branch line system.

CATV is a new communication network using coaxial cables, and has been used mainly for transmitting information centered on television images. Initially, it was used exclusively as a countermeasure for M television viewing, but in recent years, with the development of a regional information society, coaxial cables have been considered as a social system that can transmit multi-aural information by taking advantage of their characteristics. It is being

In recent years, two-way CATV, which has the function of an interactive communication network that enables not only one-way transmission but also two-way transmission, has become one of the new media that uses such CATV systems.
is being developed. This is a wired communication equipment for CATV that adds a function to send signals from the subscriber's terminal to the center, making it possible to communicate in both directions. Various services can be provided in response to requests from subscribers, such as a home security service and a pay-bar-view service that provides individual programs selected by the subscriber for a fee.

The two-way CATV transmission system usually uses a single coaxial cable, and transmits the downlink signal from the center equipment within the participating province to the upper band, and the uplink signal in the opposite direction to the lower band. A different method is used.

MC that performs data communication within such two-way CATV
In communication method A, multiple subscriber terminals jointly use multiple communication channels for mutual data communication, and when communicating between subscriber terminals and a center or between subscriber terminals via a center, When a connection request to that effect occurs, data communication is performed by allocating a vacant communication channel to both parties.

BACKGROUND ART FIG. 13 shows a schematic diagram of a conventional unidirectional CATV, in which subscriber terminals are connected to a center 10 via a main transmission line 11, a unidirectional amplifier 12, a branch transmission line 13, a tap-off 14, and a drop-in line 15. 16 are connected. Both the main transmission line 11 and the branch transmission line 13 are constructed of coaxial cables.

Furthermore, FIG. 14 is a schematic diagram of a conventional two-way CATV.
Subscriber terminals 18 are connected to the center 10 via a main transmission line 11, a bidirectional amplifier 17, a branch transmission line 13, a tap-off 14, and a drop-in line 15. The subscriber terminal 18 includes, for example, a television or a keypad connected to the home terminal 19. For example, by operating a keypad, a subscriber can make a request to the center 10 to watch a paid television program. Similar to the one-way CATV shown in FIG. 13, the main transmission line 11 and the branch transmission line 13 are composed of coaxial cables.

Further, when a CATV system is installed in an underground mall or a building, other facilities in the underground mall include a wireless public address facility shown in FIG. 15 and a wired public address facility shown in FIG. 16. Since the CATV subscriber side, broadcast speakers, etc. are fixed, all the equipment shown in Figures 15 and 16 is connected to the CATV.
Although it is possible to import it into an ATV, conventional C
Since ATV uses a coaxial cable for the transmission path, it cannot be applied to mobile objects, and has no choice but to use wireless.

Problem 1 that the invention attempts to solve: As mentioned above, in conventional CATV systems, coaxial cables were used for all transmission lines, so it was necessary to run branch lines to all subscriber homes and provide branch tap-offs. However, a service line must be drawn from this branch tap-off to the subscriber's home, which poses the problem of requiring time and effort to construct the service line.

On the other hand, TVs and home terminals are fixed in position at the subscriber's home and connected to the cable, so they cannot be moved much. Furthermore, as the number of subscribers increased, additional work such as adding tap-offs to the coaxial cable became necessary, which was complicated.

The present invention has been made in view of these points, and its purpose is to provide a two-way CATV system that does not require branch tap-offs or drop-in lines and is applicable to mobile bodies.

Means for Solving the Problems FIG. 1 shows a diagram of the principle of the present invention. In the same figure,
The center 1 and the terminals 2 are connected via a trunk coaxial cable 3, a bidirectional amplifier 4, a branch coaxial cable 5, an MCA slave station communication device 6, and a leaky coaxial cable (hereinafter referred to as LCX) 7, thereby creating a bidirectional CATV system. It consists of Terminals include, for example, industrial television cameras, keypads connected to home terminals, televisions, commercial radios, speakers, and the like.

Figure 2 shows an example of a channel plan for the LCX-CATV of the present invention, in which channels such as commercial radio and industrial television are arranged on the upstream side, and rebroadcasts, independent broadcasts, commercial radio, and emergency channels are arranged on the downstream side. Broadcasting channels etc. are arranged.

Function Since the present invention is constructed using an LCX instead of a coaxial cable for the branch transmission line, as shown in Fig. 1, it is possible to transmit the upstream image of an industrial television camera wirelessly, and it is also possible to transmit the upstream image of an industrial television camera wirelessly, as shown in Fig. 1. A normal radio can also be used by receiving leakage radio waves from the LCX. For disaster prevention radio and business radio, as shown in the channel plan example in Figure 2,
It is necessary to use different transmitting and receiving frequencies.

Furthermore, by configuring the branch line system with LCX, tap-offs and drop-in lines are not required, and since televisions and home terminals use wireless, it can also be applied to mobile objects.

Furthermore, if this system is installed in a place that is electromagnetically shielded from the outside world, such as in an underground mall or inside a building, rebroadcasts and independent broadcasts can be viewed on regular radio A or television.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a block diagram of an embodiment of the center side MCA communication device, in which signals from the main line enter the converter 21 via the head end 20. For both telephone and data systems, multiplexer/demultiplexer 22.25, control chit! Send and receive channels! fi23.26
And multiple transmissions and receptions each! 124.27. The control device 28 controls control channels and allocates communication channels, and also performs l) B X 2
9 to exchange the line. This allows CAT
Telephone and data lines can be exchanged within the V system. On the other hand, in a public communication system such as a commercial radio system, only the up converter 30 is provided because the upstream signal is simply folded back into the downstream signal.

Table 1 shows an example of a channel plan when handling telephone and data using the MCA communication system.

Table 1: The telephone/data telephone system based on the MCA system has 30 communication channels at 64 kb/s and a band of 6MH2. Also, the data system is 9.
There were 180 communication channels at 6 kb/s, and the band was 6 MHz. The public listening communication system is a communication system that can be used freely like citizen radio, but can also be heard by others, and the band is 0.2 MH2.

Figure 4 shows the M installed between the coaxial cable and LCX.
An example block diagram of a CA slave station communication device is shown. Control information (channel connection request, etc.) sent from the home terminal on the LCX side enters the control channel transceiver 33 via the demultiplexer/combiner 31 and converter 32, and then enters the LCX control device 34. The data format at this time is the 6th
The format is as shown in the figure. The LCX control device 34 adds the branch line number of the LCX to which the connection is requested, and the format is as shown in FIG. 7, and the control channel transceiver 35
The signal is then sent to the coaxial cable 5 via the demultiplexer/combiner 36, and enters the center side MCA communication device shown in FIG.

At this time, if the center side determines that the line connection partner is within the same LCX branch line, the channel assigned to the receiver of the fixed channel return device 37 shown in FIG. 4 is assigned. This channel assignment signal is sent to the demultiplexer/multiplexer 3 via the control channel.
6. Enters the terminal that has requested connection via the LCX transceiver 38 and the multiplexer/multiplexer 31, and switches the channel of that terminal to the specified communication channel. When a communication channel is specified in this way, the data passes through the transmitter/receiver 39 and is looped back by the fixed channel loopback device 37 in FIG. 4, so that mutual communication between terminals within the same branch line system is possible. Become.

In this way, in mutual communication within the same branch line system, the fixed channel loopback device 37 loops back signals to enable mutual communication, so the addition of line switching functions to the center is reduced. With this configuration, line switching can be distributed between the center and the MCA slave station communication devices, and communication channels can be used effectively.

An up-converter 40 is provided for the public listening communication system within the same branch line system, and this up-converter 40 returns the upstream signal to the downlink signal of the same branch line system. In the configuration shown in FIG. 4, upstream signals and all downstream signals except for a part of data system signals such as control information pass through the LCX transceiver 38 by the action of the demultiplexer/multiplexer 31.36. do.

Figure 8 shows an example of a channel plan that can be adopted in the MCA communication system as described above, in which the frequency band is divided into, for example, public listening communication system, telephone system, and data system from the lowest frequency, and the data system The communication channel is divided in advance into a communication channel for the entire CATV and a communication channel for use within the CATV-LCX branch line.

FIG. 5 is a block diagram of an embodiment of the LCX transmitter/receiver 1fi 38 shown in FIG. 4. A down signal from the coaxial cable 5 enters the down amplifier 41, is power amplified by the transmitter 42, and is sent to the LCX 7. The controller 43 to the game 1 turns on and off the gate switch 44 in response to a specific control signal from the center to cut upstream noise. Further, the upstream signal from the LCX 7 is sent to the coaxial cable 5 through the reception vs 45, gate switch 44, and upstream amplifier 46.

Referring now to FIG. 9, there is shown a block diagram of a data home terminal suitable for use in the present invention, including a controller 47, a control channel transceiver 1II 48, a converter 49, a channel switch 50, and a communication channel transceiver. 5
It is composed of 1.

When you operate the keypad 52 and send a connection request signal,
This signal is transmitted to the control device 47, control channel transceiver 48,
The signal enters the center through the converter 49, searches for a communication channel at the center, and sends a channel designation signal to the terminal side. In the home terminal, upon receiving this channel designation signal, the control device 47 instructs the channel switch 50 to switch the communication channel to the designated channel.

Figure 10 shows a schematic diagram of an LCX-OATV installed in an underground mall, where coaxial cables are used from the center 1 to the MCA slave station communication device 6, and LCX is used from the MCA slave station communication device 6 onwards. are doing. Furthermore, if the path is long, a repeater 8 is inserted in the middle of the coaxial cable.

In this way, in an underground mall, by providing one LCX in one passageway, it is possible to provide services to subscribers facing that passageway. On the ground, the LCX is affected by various airwaves, so the CATV system of the present invention is particularly suitable for shielded spaces such as underground malls shown in FIG.

FIG. 11 is a schematic diagram of a line exchange procedure with another LCX branch line according to the system of the present invention. When starting communication, first, a request for connection with the terminal (2) is issued from the terminal (1) to the L CX (1) device unit, that is, the MCA slave station communication device. In response to this, the LCX (1) Equipment Department:
Sends a connection request to the center via the control channel. In response to this, the center calls the terminal (2), and the terminal (2) responds to the center via the v control channel. In response to this, the center searches for and allocates a communication channel for the entire system, and controls the channel designation signal. The communication channel is sent to terminal (1) and terminal (2) via the channel, and the channels of these terminals are switched to the designated communication channel. This means that communication preparations are complete, and terminal (1) and terminal (2) perform data communication via the center.

FIG. 12 shows a schematic diagram of the circuit switching procedure within the LCX branch line, in which the terminal J1) sends a connection request with the terminal (2) to the LCX (1) device section through the IINII channel. This is received at t'j and L CX (
1) The device section sends a reward request to the center via the control channel. In response to this, Center 1, ti111! I
The terminal (2) is called through the LCX (1) 81 section by the l channel. Terminal (2) G, responds to the center via the L CX (1) equipment section via the υl channel.

In response to this, the center allocates a communication channel for the same LCX, sends a channel designation signal through the control channel, and switches the channels of terminal (1) and terminal (2) to the designated signal. This will cause the terminal (
1) and the terminal (2) and the CX (1) device unit, that is, the MCA slave station communication device, returns the upstream signal to the downstream side and performs mutual data communication.

The two-way CATV system of the present invention uses LCX in the branch line system as described in detail above, eliminating the need for tap-off or drop-in lines, and thereby reducing the need for subscriber pull-in lines. No construction work is required.Also, since TVs and home terminals use wireless, it can also be applied to mobile devices.

Furthermore, this system can be used in common with commercial radios and disaster prevention radios, and if installed in underground malls, rebroadcasts and independent broadcasts can be viewed on regular radio or television.

In addition, the MCA communication method is used for telephone and data wireless,
Install the station communication equipment to MC8 at the branch of the LCX branch line,
Two modes can be selected: closed communication within the branch line system and communication throughout the CATV.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is an example of a channel branch of the LCX-CATV of the present invention, Fig. 3 is a block diagram of an embodiment of the center-side MCA communication device used in the CATV system of the present invention, and Fig. 4 5 is a block diagram of the LCX transceiver shown in FIG. 4. FIG. 6 is the uplink III ill information format of the LCX terminal Fig. 8 is an example of a channel plan applicable to the present invention. Fig. 9 is a data home terminal block diagram. Fig. 10 is a schematic diagram of an LCX-C door TV according to the present invention installed in an underground mall. Figure 11 is a schematic diagram of the line exchange procedure with other LCX branch lines; Figure 12 is a schematic diagram of a line switcher within the same LCX branch line; Figure 13 is a schematic diagram of a conventional one-way CATV; Fig. 14 is a schematic diagram of a conventional two-way CATV, Fig. 15 is a schematic diagram of a conventional wireless public address system, and Fig. 16 is a schematic diagram of a conventional wired public address system. ,3
... Main transmission line, 4... Bidirectional amplifier, 6.
...MCA slave station communication device, 7... Branch line transmission line (LCX). I'm home. LCX main (receiver's odor/block diagram Fig. 5 Terminal force for LCX "upward shaving" now P ellipse J mat Fig. 6 and Cx force "car nail penetration quality 1; λ hit) Cape 7th side roof tile) Ormat Figure 7 Child Eiji Rubufunii Row Figure 8 Theta home terminal prog Figure Figure 9 Exit: Amplifier S: MCA+Ak4# device □ 2 Gate INBγ-Pull = τ =: LCX Underground pillar? +5LCX-CATV @ installed 'M type g<
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Terminal (1) Terminal (2) Same - LCX branch $ 1 0 lines and channels included Schematic diagram Figure 12 Figure 13 O

Claims (1)

[Claims] In a bidirectional CATV system in which a center (1) and a terminal (2) are connected by a transmission line, an MCA slave station communication device (6) is provided on the branch transmission line, and
A branch line transmission line (from the MCA slave station communication device (6) to the terminal side
7) A two-way CATV system characterized by using a leaky coaxial cable.