JPS6053390A - Relay amplifier for catv - Google Patents

Abstract

PURPOSE:To attain simple level adjustment of a relay amplifier by performing the setting of a line length equalizer circuit with a control signal from the center. CONSTITUTION:A two-way relay amplifier is provided with input/output level detecting circuits 3, 4, its level transfer circuit 6 and variable line length equalizing circuits 1, 2 and also a receiver 7 receiving a control signal transmitted from the center. An output of the receiver 7 is fed to a control circuit 5, which controls the level transfer circuit 6 and the variable type line length equalizing circuits 1, 2 based on the control input. That is, when an instruction signal of level transfer is transmitted from the center, the transfer circuit 6 is operated and when a setting signal of the equalizing circuit is transmitted, the control circuit 5 is operated and the equalizing circuit 1 is set to a designated value. Then the level signal after setting is transferred to the center.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a relay amplifier used in cable television (CATV) M installations, and relates to cable line length equalization of this relay amplifier.

The conventional line length equalization method for relay amplifiers is carried out by measuring the input and output levels at the installation location of each relay amplifier, and setting a pseudo line with optimal equalization characteristics according to the measured values. It's here.

On the other hand, repeater amplifiers used in CATV systems are generally installed overhead, suspended from Mensenger wires of coaxial cables 4 to 5 meters above the ground stretched between utility poles.

For this reason, we measure the level at the installation location of each relay amplifier.
Adjusting the relay amplifier is not easy to work with, and there are limits to measurement accuracy.

An object of the present invention is to provide a relay amplifier with a level detection and transfer function, a variable line length equalization circuit, a control circuit, etc.
The present invention aims to provide a repeater amplifier that can remotely control line length equalization adjustment.

ζTo summarize the present invention, the present invention provides a bidirectional relay amplifier with an input/output level detection circuit, a level transfer circuit, a variable line length equalization circuit (pseudo line), and a control signal transmitted from the center. It is equipped with a circuit that receives the signal and controls a level transfer circuit and a variable line length equalization circuit.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block circuit diagram showing one embodiment of a bidirectional relay amplifier according to the present invention.

(12) in the figure is an input/output terminal, for example, a high group signal (
hg). (10) is a duplexer for high and low groups,
For example, if the high group signal (hg) is input, the high group signal (hg) is input.
Only gJ is separated and output. (1) is a variable line length equalization circuit for high group use, which inputs a high group signal (hgt), adjusts it, and outputs it. (8) is an amplifier for high group, which inputs and amplifies the high group signal (6g2) and outputs it. (11) is a demultiplexer for high group and low group, for example, inputs the high group signal (hgs), demultiplexes only the high group signal (hgs), and outputs it to the input/output terminal (13). do.

(3) is a high group input/output level detector that detects the high group signal (hg I) on the input side of the line length equalization circuit (1) and the high group signal (hgs) on the output side of the amplifier (8). Each is constantly input, and the input level and output level are always detected and output.

(7) is a control signal receiver that inputs the high group signal (HGS) and receives, for example, a level transfer command signal (IN) sent from the center head end, as well as a variable line length equalization circuit. The setting signals (st) are received and outputted respectively.

(6) is an input/output level transfer circuit which inputs the input/output level signal (h7) from the detector (3) and, for example, when a level transfer command signal (in) is received, the input/output level signal ( M) is output.

(51 is a control circuit for a variable line length equalization circuit. For example, when a setting signal (8t) is received, the variable line length equalization circuit (1) for high group is specified from the center head end. set to the specified value.

On the other hand, when the terminal (13) inputs, for example, the transmitted low group signal (Ig), the high group and low group demultiplexer (11
) inputs the low group signal (Ig) and outputs the low group signal (/gl).
) is demultiplexed and output. (9) is a low group amplifier which inputs and amplifies the low group signal (A'gs) and outputs the amplified signal.

(2) is a variable line length equalization circuit for the low group, which inputs the low group signal (Jgz), adjusts it, and outputs it. In this case, the high group and low group demultiplexer inputs the low group signal (1gs), demultiplexes only the low group signal (1g4), and connects the input/output terminals (
12).

In other words, the terminal (12) - branching filter (10) -> line length equalization circuit (1) -> amplifier (8) 1 branching filter (11) -> terminal (13) ) and connect the terminal (1
3) 1 branching filter (11) → amplifier (9) → line length equalization circuit (2) → branching filter → terminal (12) is the low group circuit (1,
C).

Note that (4) is a low group input/output level detector and an amplifier (
The low group signal (1g+) on the input side of 9) and the low group signal (/gs) on the output side of the line length equalization circuit (2) are always input, and the input level and output level are constantly detected. and output it.

Thus, for example, the high group signal (hg) transmitted from the center head end (not shown) is transmitted to the input terminal (12).
, line length equalization circuit with variable high-group and low-group splitter TLL (
1) and is received by the high group amplifier (8). The input/output level of the high group signal (hg *, hg s) is constantly detected by the input/output level detector +31 Vc,
The level signal (M) is transferred to the input/output level transfer circuit (6
).

Level transfer command signal (1n) from the center head end
) is transmitted, it is received by the control signal receiver (7), operates the level transfer circuit (6), and transmits the low group circuit (
LC) to a center head end (not shown). Next, the variable line length equalization circuit setting signal (8
t) from the center head end, the variable line length control circuit (5) operates, sets the single line length equalization circuit (1) to the value specified from the center head end, and adjusts the level after setting. Signal (hl) t Transfer to center headend.

In addition, level detection of low group signal (1gt l 1g5),
Also, the setting of the variable line length is done in the same manner as described above, so the description thereof will be omitted.

Furthermore, although this embodiment describes a bidirectional relay amplifier, the same effect can be achieved even if a unidirectional relay amplifier is used by transferring the signal to the center head end via the power supply circuit.

In addition, in this case, the high group input/output level detector (3)
The level is detected using the high group signal (hg1+hg8), but for example, the input/output level is detected using the high group signal (hgt l hgm) on the input/output side of the high group amplifier (8). ↓Of course, you can do it the same way.

As described above, in the C A T 'V relay amplifier according to the present invention, the setting of the line length equalization circuit is not performed at the installation location of each relay amplifier, but is specified remotely by a control signal from the center head end. Since the level can be set to a value, it is possible to easily and accurately adjust the level of each relay amplifier, and since it is possible to constantly monitor the input and output levels at the center head end, it is possible to adjust the level of each relay amplifier easily and accurately. Since failures can be detected in advance, it is possible to construct a highly reliable CATV system.

[Brief explanation of drawings]

Figure p41 is a block circuit diagram showing an embodiment according to the present invention. l: Variable line length equalization circuit for high group 2: Variable line length equalization circuit for low group 3: High group input/output level detector 4: Low group input/output level detector 5: Variable line length control circuit 6: Input/output level transfer circuit 7: Control signal receiver 8: High group amplifier 9: Low group amplifier Patent applicant NEC Corporation

Claims (1)

[Claims] A relay amplifier &ζ used in cable television facilities includes: a circuit for detecting the input/output level of the relay amplifier; a circuit for transferring the detected level to the outside of the relay amplifier;
The relay amplifier is characterized by comprising a receiving circuit for a control signal transmitted from outside the relay amplifier, and a variable line length equalization circuit that can set a desired line equalization length using the control signal from the outside. Relay amplifier for CATV.