JP2551042B2 - Automatic switching device for transmission trunk line in CATV system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission trunk automatic switching device in a CATV system, and more particularly, to a normal transmission device when a part of the transmission trunk becomes abnormal. The present invention relates to an automatic switching device for switching and connecting transmission trunk lines.

[Prior Art] Generally, in a CATV system, the transmission trunk line is configured by wiring so as to form a dendritic transmission path with the main trunk line as a trunk.

And, on the main trunk line, VHF / LOW channel, VHF / HIGH sent from the headend connected to the common antenna
Channels, UHF channels, BS channels, and other TV broadcast signals, FM radio broadcast signals, independent broadcast programs, and other signals in which a large number of signals are superimposed are supplied. Such various signals are sent to a plurality of transmission trunk lines from the main trunk line, some trunk line amplifiers are inserted toward the end, and further, the trunk line amplifiers are divided into a plurality of branch transmission lines and further branched. It will be transmitted to the terminal equipment of many terminal subscribers via the amplifier.

[Problems to be Solved by the Invention] In a conventional CATV system, when a failure such as a disconnection accident of a cable forming a transmission trunk line or a branch trunk line or a failure of a trunk amplifier or a branch amplifier occurs, the failure point is located at the rear (end). No signal is transmitted to the terminal side, and the influence on the terminal subscriber is extremely large.

In this way, the conventional CATV system is a dendritic network and does not have a backup system or a bypass system at the time of failure, so the system will go down, and there is a limit to improving the reliability of the CATV system. It was

Of course, the CATV system should be a redundant system such as a working / standby two-unit system that can be found in equipment in a broadcasting station, but because of the enormous number of terminal subscribers,
In reality, it is extremely difficult to adopt such a measure.

Therefore, an object of the present invention is to eliminate the above-mentioned problems of the prior art, and to automatically switch to a transmission path of another system to reliably transmit a signal even if a failure occurs, to make system redundancy extremely high. (EN) It is possible to provide an automatic switching device for a transmission trunk line in a CATV system which can be achieved without increasing the cost and the facility cost significantly.

[Means for Solving the Problems] The gist of the present invention is to provide automatic switching by interposing on any one of a plurality of transmission trunks in a CATV system forming a branch network. In the device, the one set of automatic switching devices are connected to each other by a connecting line composed of two transmission lines, and each of the automatic switching devices is a self-switching device in which the automatic switching device is inserted. A first distributor for distributing and outputting a signal sent from a transmission trunk line to a first switch and a detector, and a branch signal from the other transmission trunk line sent through the connection line are input to the signal. To a terminator or the first switch, and the first switch outputs either the signal from the second switch or the signal from the first distributor. Output to the amplifier And controlling the first switch and the second switch based on a signal from the detector that detects the presence or absence of a signal sent from its own transmission trunk via the first distributor. A controller and a second distributor for distributing the output signal from the amplifier to the other automatic switching device and its own transmission trunk, and when the signal sent from its own transmission trunk is not interrupted In the above, the second switch outputs the branch signal from the other transmission trunk line sent via the connection line to the terminator, and the first switch outputs the branch signal from the first distributor. Output signal to the amplifier, and when the signal sent from its own transmission trunk line is cut off, the second switch switches from the other transmission trunk line sent via the connection line. Branch signal Is output to the first switch and the first switch
Switch is to output the signal from the second switch to the amplifier.

[Operation] In the automatic transmission trunk line switching device in the CATV system according to the present invention, a switch circuit is arranged at several points along the transmission line, and the switch circuit is connected to another opposing transmission trunk line to cause an abnormal transmission signal. This is to improve the reliability of the CATV system by automatically switching to the normal transmission trunk line when a fault is detected and minimizing the effect of failure occurrence at the time of failure.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 3.

In Fig. 1, VHF / LOW obtained with the common antenna 1
TV channels, VHF / HIGH channels, UHF channels, etc.
Many broadcast signals, such as broadcast signals and FM radio broadcast signals,
The signal is amplified to a predetermined level at the head end 2, supplied to the distributor 3 via the main transmission line A, and distributed to the _two main transmission lines B ₁ and B ₂ by the distributor 3.

This transmission trunk line B ₁ has a plurality of trunk line amplifiers at predetermined intervals.
4 ₁ to 4 _n are sequentially connected, and a plurality of main line amplifiers 5 _{1 to} 5 _n are sequentially connected to the transmission main line B ₂ at predetermined intervals, so that the signal from the transmission main line A is not attenuated and is placed in a lower order. It is supposed to be transmitted.

Each of such trunk amplifiers 4 ₁ to 4 _n and 5 _{1 to} 5 _n is
A branch output is provided, and a branch trunk line and a distribution amplifier are sequentially provided to each of the branch outputs.

When the details of the state will be described with the trunk amplifier 5 ₁ as an example, each of the transmission branches trunk C ₂ and the transmission branch trunk C ₁ trunk amplifier 5 _1, distribution amplifier 6 and 7 are connected, further the distribution amplifier The distribution output can be taken out from 6, 7 and, when the distribution amplifier 7 is taken as an example, four distribution main lines D _{1 to} D ₄
Distributors 19 _{1 to} 19 ₄ are formed in each of the above.

Therefore, various signals received by the common antenna 1 are transmitted to the terminal equipment at the end.

Here, in the middle of each of B ₁ and B ₂ of a set of transmission trunks of a plurality of transmission trunks in a CATV system forming a branch network, an automatic switcher 10 ₁ , 10 ₂ , 11 ₁ , 11 ₂ Has been inserted. In addition, the automatic switching device 13 ₁ , 14 ₁ , 15 ₁ , also between the transmission branch trunk C ₁ , the transmission branch trunk C ₂ and the distribution trunks D _{1 to} D ₄ facing _{each other} .
16 ₁ and 17 ₁ are inserted.

Connection lines 12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ and 12 ₅ are connected to the respective automatic switching devices 10 ₁ , 10 _2, ...

Therefore, for example, when a failure (disconnection, etc.) occurs in the transmission trunk line B ₁ and a signal stops flowing, the automatic switching devices 10 ₁ , 10
₂ detected respectively, switch to switch mains amplifier 4
Disconnect the connection between ₁ and the main line amplifier 4 ₂ to disconnect the connection from the transmission main line B _1, and leave the output of the main line amplifier 5 ₁ connected to the main line amplifier 5 ₂ and the input of the main line amplifier 4 ₂ via the connection line 12 _1. Main line amplifier 4 _{2 and} subsequent main line amplifiers 4 ₃
The signal of the transmission main line B ₂ is supplied from the main line amplifier 4 _n to the main line amplifier 4 _n .

Therefore, when a failure of the transmission trunk line B ₁ signal is generated, only the branch connection system of trunk amplifier 4 ₁ becomes poor, so that does not occur at all obstacles to the other strains. In other words, most of the systems will operate normally with only the minimum number of defects, and a major system down will not occur.

Next, the automatic switcher 10 ₁ construction work of the aforementioned automatic changer,
The case of 10 ₂ will be described in detail with reference to FIGS. 2 and 3.

Automatic switcher 10 ₁ is interposed between the trunk amplifier 4 ₁ and trunk amplifier 4 _2, the automatic switcher ₁₁₁ is interposed between the trunk amplifier 5 ₁ and trunk amplifier 5 _2, both the automatic switching device 10 ₁ , 11 ₁ between transmission line C,
A connecting line 12 ₁ made of C ′ is connected.

Therefore, normally, the signal from the transmission trunk line B ₁ passes through the transmission line a via the main line amplifier 4 ₁ , passes through the automatic switching device 10 ₁ , and flows as the transmission line a ′ to the next-stage main line amplifier 4 _2. .

On the other hand, similarly to the signal system from the transmission trunk line B ₁ described above, the signal from the transmission trunk line B ₂ also passes through the transmission path b via the trunk line amplifier 5 ₁ and passes through the automatic switcher 11 ₁ to form a transmission path b '. Yuku flows to the next trunk amplifiers 5 _2.

At this time, a part of the signal from the transmission line a is branched by the automatic switcher 10 ₁ to the automatic switcher 11 ₁ through the transmission line c ′.
Also from the transmission path b flows into the automatic changer 10 ₁ through the transmission path c portion of the signal is branched by an automatic switcher 11 _1, respectively it is terminating.

Each of the automatic switching units 10 ₁ and 11 ₁ is configured as shown in FIG. 3 by taking the automatic switching unit 11 ₁ as an example.

That is, 21 and 26 are power supply separation filters, 29 is a first switch, 22 is a second switch, 23 is a terminator, 24 is a controller,
25 is a detector, 27 is a power supply, 28 and 31 are distributors, and 30 is an amplifier.

Therefore, in the normal state, the second switch 22 is
23 is connected, and the first switch 29 is connected to the amplifier 30 side, the signal of the transmission line b is the power supply separation filter 26, the distributor 28, the first switch 29, the amplifier 30, the distributor 31. Through the transmission line b '. On the other hand, the signal on the transmission line c ′ is terminated by the terminator 23 via the power source separation filter 21 and the second switch 22.

Here, if a failure occurs in the transmission line b and the signal does not flow in the transmission line b ', the distribution output of the distributor 28 is lost, and the detector 25 detects this, and drives the controller 24. The second switch 22 and the first switch 29 are activated.

Then, the signal transmitted from the transmission line c'flows to the transmission line b'through the power supply separation filter 21, the second switch 22, the first switch 29, the amplifier 30, and the distributor 31. become.

With this function, even if a failure occurs in the transmission line b and the signal is not transmitted, it can be automatically switched to the distributed signal from the transmission line a of another system and transmitted to the transmission line b '.

On the other hand, when the failure of the transmission path b is recovered and a normal signal flows, the detector 25 detects it and
Since the second switch 22 and the first switch 29 by the controller 24 perform the recovery operation, the above condition, that is, the transmission line b'is connected to the transmission line b, and the signal of the transmission line c'is transmitted to the terminator 23. Restores the terminated normal state.

The automatic transmission trunk switching device in the CATV system according to the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the scope of the invention. .

For example, not only one-way CATV system but also two-way
The same can be applied to the CATV system.

Further, although the number of connecting lines for connecting the automatic switching devices is two, it is possible to use only one by adopting an appropriate switch circuit.

Further, it goes without saying that the switch forming the automatic switcher may be not only a mechanical switch but also an electronic switch such as an analog switch using a FET.

[Effects of the Invention] As is clear from the above description, according to the present invention, when a failure occurs in a certain transmission line and a signal stops flowing, another signal is automatically switched to another signal. It can be drained and can be automatically restored to the original route at the time of failure recovery, so the social anxiety of the CATV system can be eliminated.

Further, since the CATV system can be achieved without extremely increasing the redundancy of the system or significantly increasing the equipment cost, it is possible to provide the terminal subscriber with the CATV system having extremely high reliability at low cost.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an essential part of an embodiment of an automatic transmission trunk switching device in a CATV system according to the present invention, and FIG. 2 is a detailed circuit diagram of the automatic switching portion shown in FIG. FIG. 3 is a detailed circuit diagram of the automatic switching device shown in FIG. 1 ...... Common antenna 2 ...... Head end 3 ...... Distributor 4 ₁ to 4 _n , 5 _{1 to} 5 _n ...... Main line amplifier 6, 7 ...... Branch amplifier 10 ₁ 〜 18 ₁ ...... Automatic switcher 12 ₁ 〜 12 ₅ …… Connection line 1,26 …… Power supply separation filter 22 …… Second switch 23 …… Terminal 24 …… Controller 25 …… Detector 27 …… Power supply 28,31 …… Distributor 29 …… First switch 30 ... Amplifier

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Kitaro Shishido 5-1-1, Hidaka-cho, Hitachi-shi, Ibaraki Hidaka Plant, Hiritsu Electric Wire Co., Ltd. (56) References A)

Claims (1)

(57) [Claims] 1. An automatic switching device which is inserted on any one of a plurality of transmission trunks in a CATV system forming a branch network and which is automatically switched. The devices are connected to each other by a connection line composed of two transmission lines, and each of the automatic switching devices first transmits a signal sent from its own transmission trunk line in which the automatic switching device is inserted. And a first distributor for distributing and outputting to the switch and the detector, and a branch signal from the other transmission trunk line sent through the connection line, and switching the signal to a terminator or the first switch. The second switch for outputting and the first switch switch and output to the amplifier any one of the signal from the second switch and the signal from the first distributor.
A controller that controls the first switch and the second switch based on a signal from the detector that detects the presence / absence of a signal sent from its own transmission trunk via the first distributor; The output signal from the amplifier is composed of the other automatic switching device and a second distributor that distributes the output signal to its own transmission trunk line. When the signal sent from its own transmission trunk line is not interrupted, The second switch outputs a branch signal from the other transmission trunk line sent via the connection line to the terminator, and the first switch outputs the output signal from the first distributor. When the signal output to the amplifier and sent from its own transmission trunk line is cut off, the second switch outputs the branch signal from the other transmission trunk line sent via the connecting line. First The outputs to switch the first switch, automatic switching apparatus of the transmission trunk line in CATV systems and outputs a signal from the second switch to the amplifier.