JPS61167233A - Self-diagnosing circuit of two-way catv relay amplifier - Google Patents

Abstract

PURPOSE:To supervise the state without using a pilot reject filter by transmitting a state supervisory signal specific to each relay amplifier to a center even when the signal frequency is a frequency within an object of an incoming signal at failure. CONSTITUTION:A pilot generator 8 for supervising low frequency amplification generates a pilot signal having a frequency at the outside of the pass band of an incoming low frequency signal of a directional filter 3 and inserts it to the input of an incoming signal low pass amplifier 2. Its output is branched (6), detected by a detector 10 and compared with a reference level for level check. When the difference between the pilot level and the reference level is a prescribed value or over, an error detection signal is inputted to a state supervisory signal transmitter 11, from which a state supervisory signal is outputted, inserted to the incoming signal via a directional coupler 7 and the result is transmitted to the center from a line terminal 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a bidirectional CATV repeater amplifier in which a downlink signal repeater amplifier and a lily signal repeater amplifier are combined by a directional filter and inserted into a line. In particular, the present invention relates to a self-diagnosis circuit for constantly monitoring the low-frequency amplifier for the Yuri signal.

Summary of the Invention The present invention provides a bidirectional CATV relay amplifier in which a downstream signal relay amplifier and an upstream signal relay amplifier are combined by a directional filter and inserted into a line. It constantly monitors the gain of the low-band amplifier for upstream signals using This makes it possible to constantly monitor the upstream signal low-band amplifier and notify the center of any abnormalities.

Prior Art Conventionally, in a bidirectional CATV relay amplifier in which a downstream signal relay amplifier and an upstream signal relay amplifier are combined by a directional filter and inserted into a line, a unique A monitoring signal generator that oscillates a frequency is provided, and a pilot signal sent from the center or the farthest terminal from the center is inserted into the upstream and downstream signals, respectively. When an abnormality occurs in the gain reduction ring by operating the AGC not based on the pilot, the center is notified by applying low frequency modulation to the condition monitoring signal of the natural frequency.

Incidentally, a CATV system is generally configured as a dendritic network, and directional signals from all terminals are concentrated at a center. Therefore, it is necessary to use a pilot reject filter to block the pilot signal sent from the branched terminal before merging into the main line so that it does not flow into the main line. Therefore, the conventional bidirectional CATV repeater amplifier has the disadvantage that the pilot reject filter degrades the transmitted signal.

There are repeaters that do not use pilot signals, for example, using thermal AGC, but since uplink signals are not always transmitted, it becomes impossible to constantly monitor the repeater.

In addition, in order to monitor the high-band amplifier for downlink signals, when the high-band amplifier for downlink signals goes down, the uplink monitoring signal generator sends out a monitoring signal in the upstream direction, allowing the center to identify abnormalities. There is also a method, but in this case, it is not possible to monitor the status of the low-frequency amplifier, and furthermore, it is not possible to distinguish whether the interruption of the monitoring signal is due to the low-frequency amplifier going down or the power supply system going down. Can not.

OBJECTS OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional drawbacks and to provide a bidirectional C which can constantly monitor the status of a low-pass amplifier for upstream signals without using a pilot-reject filter.
An object of the present invention is to provide a self-diagnosis circuit for an ATV relay amplifier.

Structure of the Invention The self-diagnosis circuit of the bidirectional CATV relay amplifier of the present invention is as follows:
In a bidirectional CATV relay amplifier in which a high-band amplifier for downlink signals and a low-band amplifier for uplink signals are combined by a directional filter and inserted into a line, a low-pass amplifier monitoring pilot generator that generates a pilot signal and inserts it into the input of the upstream signal low-pass amplifier; and an output of the low-pass amplifier monitoring pilot generator from the output of the upstream signal low-pass amplifier. a detector that separates and extracts a pilot signal and detects a level abnormality therein; a condition monitoring signal generator that generates a condition monitoring signal of a unique frequency within the uplink signal band and assigned to each repeater; and the detector. and a condition monitoring transmitter for transmitting the condition monitoring signal 1t1 to the line via the directional filter based on the abnormality detection output.

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

The figure is a block diagram showing one embodiment of the present invention. That is, the high-band amplifier 1 for downlink signals and the low-band amplifier 2 for uplink signals are coupled by directional filters 3 and 4, and the line terminal 1
Insert and connect 2 and 13 to the track, and connect the line terminal 12 from the center.
The downlink signal input to is inputted to the downlink signal high frequency amplifier l through the directional filter 3, where it is amplified and sent out through the directional filter 4 from the line terminal 13 toward the terminal. The upstream signal input from the terminal direction to the line terminal 13 is input to the upstream signal low-pass amplifier 2 through the directional filter 4, where it is amplified and sent to the directional filter 3.
It is sent out from the line terminal 12 to the center side through the line.

The low-pass amplifier monitoring pilot generator 8 generates a pilot signal with a frequency outside the low-pass signal passband of the directional filter 3 and passes it through the directional coupler 5 to the upstream signal low-pass amplifier. Insert into the input of 2.

The output of the upstream signal low-band amplifier 2 is branched by a directional coupler 6 and input to a detector 1O, where the pilot signal is separated and extracted and compared with a reference level for level checking. When the difference between the pilot level and the reference level is more than a certain value.

An abnormality detection signal is sent from the detector IO to the status monitoring signal transmitter 11
sent to. On the other hand, the output of the low-band amplifier monitoring pilot generator 8 is frequency-divided by a frequency divider 9 and converted into a status monitoring signal with a frequency specific to the relay amplifier within the upstream signal band, and then sent to a status monitoring signal transmitter. 11 is input. When the abnormality detection signal is input, the condition monitoring signal transmitter 11 outputs the condition monitoring signal, and the directional coupler 7
It is inserted into the upstream signal via the directional filter 3 and sent from the line terminal 12 to the center. Therefore, it is possible to send out a status monitoring signal even when the low-band amplifier is disconnected.
It is possible to distinguish this from a power outage.

In this embodiment, a low-band amplifier monitoring pilot generator 8 and a frequency divider 9 constitute a condition monitoring signal generator, and a frequency unique to each repeater is generated by the frequency division ratio of the frequency divider 9. However, it goes without saying that the condition monitoring signal generator may use a separate oscillator for each relay amplifier.

Effects of the Invention As described above, in the present invention, the gain of the low-frequency amplifier for uplink signals is constantly monitored using a frequency outside the band of uplink signals, and when an abnormality occurs, the gain of the low-frequency amplifier for uplink signals is Since the configuration is configured to send a status monitoring signal specific to the amplifier to the center, the status of the low-band amplifier for upstream signals can be constantly monitored without using a pilot reject filter and therefore without causing deterioration of the upstream transmission signal. It has the effect of being able to

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. In the figure, 1: high-frequency amplifier for downstream signals, 2: low-frequency amplifier for two-way signals, 3, 4 bidirectional filters, 5 to 7: directional coupler, 8: pilot generator for monitoring low-frequency amplifiers. ,9
: Frequency divider, lO: Detector, 11: Status monitoring signal transmitter,
12, 13: Line terminals.

Claims (1)

[Scope of Claims] A bidirectional CATV repeating amplifier in which a high-band amplifier for downlink signals and a low-band amplifier for uplink signals are combined by a directional filter and inserted and connected into a line, wherein the directional filter a low-pass amplifier monitoring pilot generator that generates a pilot signal with a frequency outside the upstream signal passband and inserts it into the input of the upstream signal low-pass amplifier; A detector that separates and extracts the pilot signal output from the monitoring pilot generator and detects level abnormalities, and a status monitor that generates a status monitoring signal with a unique frequency that is within the uplink signal band and is assigned to each repeater. A two-way CATV relay comprising: a signal generator; and a condition monitoring signal transmitter that transmits the condition monitoring signal to the line via the directional filter based on the abnormality detection output of the detector. Amplifier self-diagnosis circuit.