JPH01114285A - Automatic switching device for transmission trunk in catv system - Google Patents

Abstract

PURPOSE:To prevent an increase in the redundancy of a system and the increase in the cost of equipment by permitting a switch circuit to switch the side of a normal transmission trunk on the side of the low-order transmission line of an abnormal transmission trunk based on the abnormal detected output of a detection circuit. CONSTITUTION:When a fault occurs in a transmission trunk B1 and a signal does not flow, automatic switches 101 and 102 detect it, and the switches are changed over, whereby the connection of trunk amplifiers 41 and 42 is disconnected so as to disconnect from the transmission trunk B1. While the output of a trunk amplifier 51 is connected to a trunk amplifier 52, the output is connected to the input side of the trunk amplifier 42 through a connection line 121, and the signal of the transmission trunk B2 is supplied from a trunk amplifier 43 to a trunk amplifier 4n subsequent to the trunk amplifier 42. Since switching is automatically executed to the other transmission line, the increase in the redundancy of the system and the increase in the cost of equipment can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic switching device for transmission trunk lines in a CATV system, and more specifically, when a part of the transmission trunk line becomes abnormal, it switches to another normal transmission line. 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 with wiring that forms a tree-like transmission line with the main trunk line as the trunk.

The main trunk line is a VHF-10W channel sent from the head end connected to the common antenna, Vl
-IF-HIG+-1 channel, UHF channel,
A superimposed signal of a large number of signals such as TV broadcast signals such as BS channels, FM radio broadcast signals, and independent broadcast programs is supplied. These various signals are sent out from the main line to multiple transmission lines, several main line amplifiers are inserted toward the end, and then branched from this main line amplifier to multiple branch transmission lines, and then branch amplifiers are inserted into the main line. The data will be transmitted to the terminal equipment of a large number of terminal subscribers via the terminal.

[Problems to be Solved by the Invention] In conventional CATV systems, when a failure occurs such as a disconnection accident in a cable forming a transmission trunk line or a branch trunk line, or a malfunction in a trunk amplifier or branch amplifier, it is necessary to Signals are not transmitted to terminals (near the terminals), which has an extremely large impact on terminal subscribers.

As described above, conventional CATV systems are dendritic networks and do not have backup systems or detour systems in case of failure, so system failures occur, and there is a limit to the improvement in reliability of CATV systems. there were.

However, it would be better to use the CA-V system as a redundant system, such as a two-unit system for active use and reconnaissance unit, as seen in equipment in broadcasting stations, but due to the large number of terminal subscribers, this is not possible. In reality, it is extremely difficult to adopt such measures.

Therefore, the purpose of this invention is to solve the above-mentioned problems of the prior art and to automatically switch to a different transmission line even if a failure occurs to reliably transmit signals, or to maximize system redundancy. A C A TV system that can be achieved without increasing the axis or significantly increasing the installation cost (Mj).
Our purpose is to provide an automatic switching device for transmission trunk lines.

[Means for Solving the Problems] In the CATV system according to the present invention, an automatic switching device for a transmission trunk line is used to connect a CATV system forming a branch network.
A switch circuit inserted between each of a given set of transmission trunks among the plurality of transmission trunks connected to the system, and a detection circuit for detecting an abnormality in each of the transmission trunks, The present invention is characterized by comprising a control circuit that switches the switch circuit from the normal transmission trunk side to the lower transmission path side of the abnormal transmission trunk line based on the abnormality detection output of the detection circuit.

[Function] The automatic switching device for transmission trunk lines in a CATV system according to the present invention has switch circuits arranged at several locations along the transmission line, and connects the switch circuits to other transmission trunk lines facing each other to switch transmission signals. By automatically switching to a normal transmission trunk line when an abnormality is detected, the reliability of the CA-V system is improved by minimizing the effects of faults such as failures.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 3.

In Figure 1, VHF-L obtained by communal antenna 1
A large number of broadcast signals such as TV broadcast signals such as OW channel, V) (F・l-I IG l-1 channel, UHF channel, FM radio broadcast signal, etc.) are sent to the head end 2.
The amplified signal is amplified to a predetermined level by the main transmission line A, and is supplied to the distributor 3 via the transmission main line A, and the distributor 3 amplifies the two transmission main lines B1 .
It is distributed to B2.

A plurality of main line amplifiers 41 to 4 are sequentially connected to the transmission main line B1 at predetermined intervals, and a plurality of main line amplifiers 51 to 5 are sequentially connected to the transmission main line B at predetermined intervals. The signal from main line A is transmitted downstream without attenuation.

Each of the main line amplifiers 4 to 4 degrees and 51 to 5 degrees is provided with a branch output, and each branch output is sequentially provided with a branch main line and a distribution amplifier.

To explain the details of this state using the trunk amplifier 51 as an example, the transmission branch trunk line C1 and the transmission branch trunk line C1 of the trunk amplifier 51 are
A distribution amplifier 6.7 is connected to each of the distribution amplifiers 6 and 2, and the distribution output can be taken out from the distribution amplifiers 6 and 7. Taking the distribution amplifier 7 as an example, four distribution trunk lines D1 to D4 are connected to each of the distribution amplifiers 6 and 7. Distributors 191 to 194 are formed in each of them.

Therefore, various signals received by the communal antenna 1 are transmitted to the terminal equipment.

Here, the 81.
In the middle of each of B2, there is an automatic switch 10. 102
, 111, 112 are inserted. Also, automatic switching devices 131, 14 . 151,161.
'171 is inserted.

Connecting wires 12 . 122,123゜1
24.125 are connected.

Therefore, for example, if a failure (such as a disconnection) occurs in the transmission trunk line B1 and the signal no longer flows, the automatic switching device 101
, 102, the switch is switched to disconnect the main amplifier 41 and the main amplifier 42, and disconnect the connection from the transmission main line B1. to the input side of the mains amplifier 42 via the mains amplifier/
12 and subsequent trunk amplifiers 43 to trunk amplifiers 4. The signal from the transmission main line B2 is supplied until then.

Therefore, when a signal failure occurs on the transmission main line B1, only the branch connection system of the main line amplifier 41 becomes defective, and no failure occurs in the other systems. In other words, most systems can operate normally with only the minimum number of defects required, and major system downtime is prevented.

Next, the configuration and operation of the automatic switching device (above) automatic switching device 10
The case of 1,102 will be explained in detail using FIGS. 2 and 3 as an example.

An automatic switching device 1 is installed between the main line amplifier 41 and the 9 full line waste width device 42.
01 is inserted, an automatic switch 111 is inserted between the main amplifier 51 and the main amplifier 520, and both automatic switch 101,
A connection line 121 consisting of transmission lines c and c' is connected between the lines 111 and 111.

Therefore, under normal conditions, a signal from the transmission main line B1 passes through the transmission line a via the main line amplifier 41, passes through the automatic switch 101, and flows to the next stage main line amplifier 42 as the transmission line 'a'.

On the other hand, similarly to the signal system from the transmission trunk line B1 described above, the signal from the transmission trunk line B2 passes through the transmission line via the trunk amplifier 51, passes through the automatic switch 111, and is transferred to the next stage trunk line as the transmission line b'. The signal flows to the amplifier 52.

At this point, part of the signal from the transmission line a is branched at the automatic switch 101 and sent to the automatic switch 111 through the transmission line C, and part of the signal from the transmission line is branched to the automatic switch 111.
1, and flows through a transmission line C' to an automatic switching device 101, and each terminal is connected.

Each of the automatic switching devices 101 and 111 is configured as shown in FIG. 3, taking the automatic switching device 101 as an example.

That is, 21.26 is a power separation filter, 22 is a first switch, 29 is a second switch, 23 is a terminator, and 24
is a controller, 25 is a detector, 27 is a power supply, 28.31 is a distributor, and 30 is an amplifier.

Therefore, in normal times, the first switch 22 is connected to the terminator 23 side, and the second switch 29 is connected to the amplifier 30 side, so the signal on the transmission line C is transmitted to the power supply separation filter 262, the distributor 28,゜Second switch 29. The signal flows to the transmission line C' via the increasing sequential order. On the other hand, the signal on the transmission line a is terminated at the terminator 23 via the power separation filter 21 and the first switch 22.

Here, if a failure occurs in the transmission line C and the signal no longer flows through the transmission line C', the detector 25 detects that the distribution output of the distributor 28 has disappeared, and the controller 24 is driven. The first switch 22 and the second switch 29 are activated.

Then, the signal transmitted from the transmission line a is passed through the power separation filter 21, the first switch 22, and the second switch 2.
9, the amplifier 30, the distributor 31, and the transmission line a'.

Due to this function, even if a failure occurs in the transmission line C and the signal is no longer transmitted, the signal can be automatically switched to the signal distributed from the transmission line a of another system and transmitted to the transmission line a'.

On the other hand, if the fault in the transmission line C is restored and a normal signal flows, the detector 25 detects it and
Since the first switch 22 and the second switch 29 are operated by the controller 24, the above-mentioned state, that is, the transmission line a
The normal state in which transmission line a' is connected to transmission line C and transmission line C' is restored to normal state is restored.

The automatic switching device for the transmission trunk connected to the C A TV system according to the present invention is not limited to the above-described embodiments, and may be modified in various ways without departing from the gist thereof. Of course it is possible.

For example, it can be applied not only to a unidirectional CATV system but also to a bidirectional CATV system.

Further, although there are two connection lines for connecting the automatic switching devices, it is also possible to use one connection line by employing an appropriate switch circuit.

Furthermore, it goes without saying that the switches forming the automatic changeover are not limited to mechanical ones, but may also be electronic switches such as analog switches using FETs.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, when a failure occurs in a certain transmission line and the signal stops flowing, the signal is automatically switched to another transmission line and the signal is transmitted. This eliminates the social concerns of the CA engineering V system, since it can be done without automatically returning to the original route when a failure is restored.

Further, since a CATV system can be achieved without extremely increasing system redundancy or significantly increasing equipment costs, a highly reliable CATV system can be provided to terminal subscribers at low cost.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the essential parts of an embodiment of an automatic switching device for transmission trunks used in the CA-V system according to the present invention, and FIG. Detailed circuit diagram of switching portion FIG. 3 is a detailed circuit diagram of the automatic switching device shown in FIG. 2 above. 1...Common antenna 2...Head end 3...Distributor 41-4□, 51-5□...・Main amplifier 6.7
......Branch amplifiers 101-181...Automatic switching device 121-
125・・・・・・Connection line 1.26・・・・・・
...Power separation filter 22...1st
Switch 23...Terminator 24...Controller 25...Detector 27...Power supply 28 .31...Distributor 29...Second switch 30...
...Amplifier patent applicant Hitachi Cable Co., Ltd. Agent 1) Mitsuo Koyama

Claims (1)

[Scope of Claims] A switch circuit inserted between each of an arbitrary set of transmission trunk lines among a plurality of transmission trunk lines in a CATV system forming a branch network; and each of the set of transmission trunk lines. A CATV comprising: a detection circuit that detects an abnormality; and a control circuit that switches the switch circuit from the normal transmission trunk side to the lower transmission line side of the abnormal transmission trunk based on the abnormality detection output of the detection circuit. Automatic switching device for transmission trunk lines in a system.