JPS63314984A - Catv circuit network - Google Patents

Abstract

PURPOSE:To limit a fault occurring in a CATV circuit network in a small range by means of a mesh like circuit network by using a trunk amplifier provided with a three input/three output signals port for a trunk amplifier, detecting signal fault by means of a detection circuit and constituting a bypass transmission line. CONSTITUTION:The trunk amplifiers 20-1, 20-2,...40-4 having the three input/ three output signals port constitutes the three like circuit network transmitting a broadcasting wave from a CATV center 10 by a course shown by a continuous line when the fault does not exist at the transmission line. For example, when the fault occurs at the trunk amplifier 30-2, the trunk amplifier 40-2 detects the abnormality by it's input signal level fault detecting function and sends a bypass network control signal to the adjacent trunk amplifier 40-4 through the bypass line of a dotted line. The trunk amplifier 40-4 branches the broadcasting wave from the center 10 by operating the output switching function of it, supplies it to the trunk amplifier 40-2 through the bypass line and guarantees the transmission of the broadcasting wave to the low area of the circuit network. Thus the fault area can be limitted even in a large scale system.

Description

[Detailed Description of the Invention] [1 Already Required] In a CATV circuit network with a tree-like configuration, a trunk amplifier equipped with 3 inputs and 3 outputs signal ports is used, and a signal failure is detected by a detection circuit and bypassed. A transmission path is constructed, and a fault occurring in a CATV network is limited to a small area using a mensch-like network.

[Industrial application field]

The present invention relates to improvements in CATV networks.

In a CATV system, it is desirable to have a circuit network configuration that can transmit broadcast signals from a center to as many terminal devices as possible.

[Conventional technology]

Conventionally, a CATV system is configured as a tree-like network, as shown in FIG.

In the figure, 1 is a CATV center, 2-1.2-2,
..., 4-6 is a trunk amplifier.

The line starting from CATV center 1 is first branched into two, reaching trunk amplifier 2-1.2-2, and then divided into two again to trunk amplifiers 3-1, 3-3 and 3-2.3.
It becomes a track to -4. Similarly, trunk amplifier 3-3.
It is further branched at 3-4 into 6 lines.

For signals sent from the center, the circuit network is structured in a tree shape so that branched broadcast waves do not go around via other branch lines and join together again.

That is, the conventional CATV network has a tree-like configuration so that signals sent from one CATV center do not reach the same terminal device through two or more routes and cause mutual interference. Furthermore, as the circuit scale increases, the tree also increases accordingly.

[Problem that the invention seeks to solve]

In the above-mentioned conventional CATV circuit network having a tree-like configuration, as shown in FIG. The area is affected and becomes unable to receive broadcast signals.

The larger the scale of the circuit network (the higher the level where the fault occurs, the wider the range of influence will be, so the challenge is to keep the fault within a small range).

[Means for solving problems]

According to the present invention, as shown in the principle diagram of the present invention in FIG.
A mesh-like CATV circuit network is configured with a trunk amplifier that has a fault detection function that monitors the input signal level and 3 input and 3 output signal ports that have an input/output switching function, and when an abnormality in the trunk amplifier signal input is detected, the bypass The above-mentioned problems have been solved by the CATV circuit network of the present invention, which switches the input line so that the bypass network control signal can be sent through the line and the signal from other trunk amplifiers can be received through the bypass line. .

[Effect]

According to the present invention, trunk amplifiers 20-1, 20-2, . Construct a tree-like circuit network that transmits waves.

For example, if a failure occurs in trunk amplifier 30-2,
Trunk amplifier 40-2 detects an abnormality using an input signal level failure detection function, and sends a bypass network control signal to adjacent trunk amplifier 40-4 via a dotted bypass line. The trunk amplifier 40-4 branches the broadcast wave from the center 10 by operating the output switching function, and supplies it to the trunk amplifier 40-2 via a bypass path, thereby ensuring transmission of the broadcast wave to the lower region.

〔Example〕

The present invention will be explained according to illustrated embodiments.

FIG. 2 is a trunk amplifier connection diagram according to an embodiment of the present invention.

The trunk amplifier consists of a three-man department of ■, ■, ■ and ■゛, ■'',
■It has 3 output parts.

The input signal of the one-person power section can be outputted to one or more output sections by the switching means.

FIG. 3 is a block circuit diagram of a three-input, three-output crank amplifier according to an embodiment of the present invention.

3-person power input port 201, bypass input port 203
．． 205, and the three outputs are an output port 202 and a bypass output port 204.206.

Reference numeral 207 denotes an input selector switch, which selectively connects the input port to the amplifier 213. The signal amplified by the amplifier is outputted from the output port 202, bypass output port 204, or 206 via the output changeover switch 208.

Reference numeral 209 denotes a failure detection circuit, which can be configured by a detection circuit and a level detection circuit.

The fault detection circuit 209 detects and monitors, for example, a pilot signal received from the upper (CATV center side) trunk amplifier, and when the reception level falls below a specified value, the CPU
Network control signal transmitter 2 bypasses the fault signal via 210
Give to 12.

The bypass network control signal sending unit 212 sends the network control signal from the bypass output port to other trunk amplifiers that should constitute a bypass path.

When the bypass network control signal detection unit 211 detects the network control signal, it switches the input changeover switch 207 and the output changeover switch 208 via the CPU to complete the broadcast wave signal path from the changeover center.

Figure MDA and Figure 4B show the bypass transmission line switching process of the trunk amplifier.

If the trunk amplifier 40-2 cannot receive a normal level signal from the trunk amplifier 30-2 to the input port (
(The dotted arrow indicates a decrease in the input signal level), and as a result of detecting an abnormal reception level, the bypass network control signal is sent from the bypass output port ■'' to the bypass input port ■ of the trunk amplifier 40-4, as shown in FIG. 4a. send.

Is the trunk amplifier 40-4 on the bypass network side in the network control signal detection section? II signal is detected, the input selector switch and the output selector switch are switched, and as shown in Figure 4b, part of the broadcast signal received from the center and sent from the input port ■ to the output port ■' is branched using the selector switch. and sends it from the bypass output port ■'' to the bypass input port ■ of the trunk amplifier 40-2.

The trunk amplifier 40-2 sends out the input broadcast wave signal from the bypass input port (2) to the lower layer transmission path from the port (2).

In this way, the fault area is limited to a small area where the fault occurs.

〔Effect of the invention〕

According to the present invention, it is possible to configure a mensch-like circuit network for a broadcast signal when a fault occurs, and to localize the fault area even in a large-scale system, and its effects are extremely large.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram of the present invention, Fig. 2 is a trunk amplifier connection diagram according to an embodiment of the present invention, Fig. 3 is a block circuit diagram of a 3-input 3-output trunk amplifier according to an embodiment of the present invention, and Fig. 4a. , FIG. 4b is a bypass transmission line switching process diagram according to an embodiment of the present invention, and FIG. 5 shows a conventional tree-shaped CATV circuit network. In the figure, 1.10 is CATV-t=7 ter, 2-1.2-2
．． 3-1~3-4.4-1~4-6.20-1~20-
2, 30-1 to 30-4. 40-1 to 40-4 are trunk amplifiers, 201 is an input port, 202 is an output port, 203.205 is a bypass input port, 204.206
is a bypass output port, 207 and 208 are changeover switches, 209 is a failure detection circuit, and 210 is a CPU. 211 is a bypass network control signal detection section, 212 is a bypass network control signal transmission section, and 213 is an amplifier.

Claims (1)

[Claims] A CATV circuit network comprising a trunk amplifier having 3 input and 3 output signal ports, which has a failure detection function for monitoring input signal levels and an input/output switching function.