JPH11122597A - Relay amplifier for catv system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect communication equipments and prevent a signal from being distorted by providing a signal selection circuit that selects an outgoing signal branched/distributed at a pre-stage of an outgoing amplifier circuit of an amplifier or an outgoing signal branched/distributed at a post-stage of the outgoing amplifier circuit of the amplifier and an output spare terminal from which externally outputs the outgoing signal selected by the signal selection circuit without connecting a branching device and a distributer. SOLUTION: The relay amplifier of a single-way or 2-way CATV system is provided with a signal selection circuit 2 that selects an outgoing signal branched/distributed at a pre-stage of an outgoing amplifier circuit 1 of the amplifier or an outgoing signal branched/distributed at a post-stage of the outgoing amplifier circuit 1 of the amplifier and with an output spare terminal 3 from which externally outputs the outgoing signal selected by the signal selection circuit 2. The amplifier is also provided with an input spare terminal 4 that receives an external signal, and a signal changeover circuit 6 that gives the signal received at the input spare terminal 4 to the pre-stage or the post- stage of an incoming amplifier circuit 5 and mixes the signal into an incoming signal amplified by the amplifier circuit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a repeater amplifier for a CATV system.

[0002]

2. Description of the Related Art A bidirectional CATV trunk amplifier has an input terminal A and an output terminal B as shown in FIG. A downstream signal from the head end is input to the input terminal A, and an upstream signal input from the output terminal B and amplified by the upstream amplifier circuit C is output. The output terminal B receives an upstream signal from the terminal device side, and outputs a downstream signal that is input from the input terminal A and amplified by the downstream amplifier circuit D. Conventionally, there is a branch amplifier as shown in FIG. This amplifier has two to four branch terminals E in addition to an input terminal A and an output terminal B. These branch terminals E have input terminals A
To the downstream amplifier circuit D and the branch-side downstream amplifier circuit F
The downstream signal amplified in is distributed and output, and the upstream signal is input from the branch-side terminal device. This upstream signal is amplified by the branch-side upstream amplifier circuit G and the upstream amplifier circuit C and output to the input terminal A. It has become so.

[0003]

Conventionally, when a communication device or the like is separately connected to an amplifier as shown in FIGS. 2 and 3 to perform communication, there are the following problems. 1. In the bidirectional amplifier of FIG. 2 which does not include the branch terminal E of FIG. 3, it is troublesome that the number of terminals for connecting a communication device by newly connecting a branch or a distributor is increased, and the cost is increased. Will be high. 2. In the branch amplifier of FIG. 3, communication can be performed by connecting a communication device to the branch terminal E. However, connecting a communication device to the branch terminal E directly or with a short cable causes the following problem. The branch terminal E assumes that a long coaxial cable is connected in the same manner as the input terminal A and the output terminal B to which the main cable is connected. It is designed to be amplified. Therefore, if a communication device is directly connected to the branch terminal E or via a short cable, an excessively high uplink signal is input to the branch terminal E, or an excessively low downlink signal is input to the communication device. These cause distortion in the signal on the main line or in the signal for communication with the communication device. This is the same when a branching device or a distributor is connected to the main amplifier of FIG.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to enable communication equipment to be connected without connecting a new splitter or distributor, and to prevent signal distortion even when signals of different levels are input. To provide a repeater amplifier for a CATV system.

As shown in FIG. 1 of the present invention, a relay amplifier for a CATV system according to the present invention is a branch amplifier for a unidirectional or bidirectional CATV system, which is provided at a stage preceding the downstream amplifier circuit 1 in the amplifier. A signal selection circuit 2 that can select either one of the divided signal divided / distributed in the subsequent stage of the amplifier circuit 1 and the divided signal divided / divided;
An output spare terminal 3 for externally outputting the downstream signal selected by the signal selection circuit 2 is provided.

A repeater for a CATV system according to a second aspect of the present invention, as shown in FIG.
In an ATV system relay amplifier, an input spare terminal 4 for inputting an external signal, and a signal input to the input spare terminal 4 are input to one of a preceding stage and a succeeding stage of an up-amplifying circuit 5 to perform the same amplification. It is characterized by including a signal switching circuit 6 adapted to be mixed with the upstream signal amplified by the circuit 5.

As shown in FIG. 1, the relay amplifier for a CATV system according to the third aspect of the present invention includes a downstream signal branched / distributed in a stage preceding the downstream amplifier circuit 1 and the same amplifier circuit 1.
A signal selection circuit 2 capable of selecting either one of the downstream signals branched / distributed in the subsequent stage, and an output spare terminal 3 for externally outputting the downstream signal selected by the signal selection circuit 2. It is assumed that.

[0008]

FIG. 1 shows an embodiment of a repeater amplifier for a CATV system according to the present invention. This amplifier has a new output spare terminal 3 and a new input spare terminal 4 in addition to the usual input terminal 10 and output terminal 11.

The input terminal 10 is a terminal to which a downstream signal from a head end (not shown) is input. The input downstream signal is split by a splitting filter 12 and amplified by a downstream amplifier circuit 1 to be separated. The signal is multiplexed with the upstream signal by the wave filter 13 and output to the output terminal 11.
The output terminal 11 is a terminal to which an upstream signal from a terminal device (not shown) is input. The input signal is split by the splitter filter 13, amplified by the upstream amplifier circuit 5, and output by the splitter filter 12. And is output to the input terminal 10 after being multiplexed with the downstream signal.

On the circuit between the demultiplexing filter 12 and the downstream amplification circuit 1 and on the circuit between the downstream amplification circuit 1 and the demultiplexing filter 13, a part of the downstream signal input to the input terminal 10 Branching devices 14 and 15 are provided for branching the downstream signal. The two branch outputs of the branchers 14 and 15 are input to the signal selection circuit 2, and one output selected by the circuit 2 is output to the output spare terminal 3. That is, one of the downstream signal before amplification amplified by the branch unit 14 and the downstream signal after amplification branched by the branch unit 15 is selected by the signal selection circuit 2 and output to the output spare terminal 3. I can do it.

On the circuit between the demultiplexing filter 12 and the up-amplifying circuit 5, and on the circuit between the up-amplifying circuit 5 and the demultiplexing filter 13, the input terminal 1
Branch devices 16 and 17 are provided for mixing an external upstream signal with the upstream signal output from 0. These switches 1
6 and 17 are connected to the signal switching circuit 6;
Are connected to the input spare terminal 4. That is, when an external signal is input to the input spare terminal 4, the external signal can be mixed and input to one of the upstream and downstream stages of the up-amplifying circuit 5 by the signal switching circuit 6, and the external signal can be amplified. Then, it is possible to select whether to output from the input terminal 10 or to output from the input terminal 10 without amplification.

The relay amplifier for a CATV system according to the present invention may have a configuration in which only one of the output spare terminal 3 and the input spare terminal 4 is provided. If the amplifier is for one direction, only the output spare terminal 4 is provided. In addition, when both the output spare terminal 3 and the input spare terminal 4 are provided, a configuration in which these terminals are integrated into one terminal is also possible. In this case, a branching filter (the same as the branching filters 12 and 11) is provided in front of the input / output spare terminal,
The upstream signal input to the input / output auxiliary terminal is input only to the signal switching circuit 6 through the demultiplexing filter, and the downstream signal selected by the signal selection circuit 2 is output to the input / output auxiliary terminal.

[0013]

According to the relay amplifier for CATV system of the first aspect of the present invention, the following effects can be obtained. If a communication device or the like is connected to the output spare terminal 3, a signal transmitted to the relay transmission line of the CATV system can be input to the communication device or the like. In this case, if the signal selection circuit 2 is switched, the level of the downstream signal input to the communication device or the like can be switched between the level before amplification and the level after amplification.

According to the relay amplifier for a CATV system of the second aspect of the present invention, the following effects can be obtained. If a communication device or the like is connected to the input spare terminal 4, the output of the communication device or the like can be mixed and input to the relay transmission line of the CATV system. In this case, if the signal switching circuit 6 is switched, the output of the communication device can be input to the relay transmission line from one of the upstream and downstream stages of the upstream amplification circuit 5, and the level of the signal mixed into the relay transmission line can be adjusted. can do.

According to the relay amplifier for CATV system of the third aspect of the present invention, the following effects can be obtained. If a communication device or the like is connected to the output spare terminal 4 and the input spare terminal 6, a signal transmitted to the relay transmission line of the CATV system can be input to the communication device or the like, and the output of the communication device can be relayed to the CATV system. It can be mixed and input to the road. Moreover, the signal level can be adjusted so as to achieve the effects of the first and second aspects.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a relay amplifier for a CATV system according to the present invention.

FIG. 2 is a circuit diagram showing an example of a conventional bidirectional amplifier for a CATV system.

FIG. 3 is a circuit diagram showing an example of a conventional bidirectional branch amplifier for a CATV system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Down-amplifier circuit 2 Signal selection circuit 3 Output spare terminal 4 Input spare terminal 5 Up-amplifier circuit 6 Signal switching circuit

Claims (3)

[Claims] 1. A relay amplifier for a unidirectional or bidirectional CATV system, comprising: a downstream signal branched / distributed before a downstream amplifier circuit (1) in the amplifier; and a branch / distribution downstream of the amplifier circuit (1). A signal selection circuit (2) capable of selecting one of the selected downstream signals, and an output spare terminal (3) for externally outputting the downstream signal selected by the signal selection circuit (2). For a CATV system. 2. An input spare terminal for inputting an external signal in a relay amplifier for a bidirectional CATV system.
And the signal input to the input spare terminal (4) can be input to one of the upstream and downstream stages of the upstream amplifier circuit (5) so as to be mixed with the upstream signal amplified by the amplifier circuit (5). A relay amplifier for a CATV system, comprising a signal switching circuit (6) according to (1). 3. A signal selection circuit (1) capable of selecting one of a downstream signal branched / distributed in a stage preceding the downstream amplifier circuit (1) and a downstream signal branched / distributed in a stage subsequent to the amplifier circuit (1). 3. The repeater amplifier for a CATV system according to claim 2, further comprising: (2) an output spare terminal (3) for externally outputting the downstream signal selected by the signal selection circuit (2).