JP2002094958A - Catv device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CATV device that can specify a noise generating or confluent position at less expense, time and effort. SOLUTION: This invention provides any of various CATV devices such as trunk line amplifiers used for a 2-way CATV system that is provided with a gate switch 2 that can interrupt an incoming transmission line 1/release the interruption of the incoming transmission line 1, a branching device 4 that extracts a part of an incoming signal and noise propagated through the incoming transmission line 1, a band elimination filter 5 that blocks passing of the incoming signal in the incoming signal and the noise extracted by the branching device 4, and a comparator 8 that compares the noise passing through the band elimination filter 5 with a reference voltage, activates the gate switch 2 when the output voltage of the filter 5 exceeds the reference voltage to interrupt the incoming transmission line 1 and provides an output of a prescribed signal to a status monitor 3 at all times, and the status monitor 3 receiving the output of the comparator 8 transmits information denoting a noise level to a center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various types of CATV equipment such as a main line amplifier, a branch amplifier, an extension amplifier, a distributor, a branch unit, a home branch unit, a home amplifier, etc., connected to a transmission network of a bidirectional CATV system. It is.

[0002]

2. Description of the Related Art In a bidirectional CATV system, ingress noise flowing into a center via an upstream transmission line has been a major problem. Therefore, at present, when the ingress noise level at the center exceeds a predetermined value, the upstream outputs of a large number of amplifiers connected to the CATV transmission network are cut off in order from the amplifier farthest to the center to the amplifier close to the center. Measure the ingress noise level at the center each time, identify the amplifier with the reduced ingress noise level as the location of noise generation or inflow, and take measures to prevent the occurrence or inflow of noise into the amplifier. I have. In this case, the interruption of the amplifier is performed in the following manner. (1) A worker goes to each amplifier connected to the CATV transmission network, and sequentially turns off the power of the up-amplifier of each amplifier.
To (2) Each amplifier connected to the CATV transmission network is provided with a gate switch capable of blocking and releasing the upstream transmission path, and a worker who has arrived at the amplifier operates the gate switch to operate the upstream of each amplifier. Shut off the output sequentially. (3) A status monitor for controlling the gate switch is provided in the amplifier of (2), and a signal is transmitted from the center to the status monitor of each amplifier without a worker going to each amplifier, thereby enabling the gate switch. By operating, the upstream output of each amplifier is sequentially cut off.

[0003]

There are the following problems in specifying a noise generation location or an inflow location as described above. (1) In the above method (1) or (2), a worker must go directly to each amplifier connected to the transmission network, and check each amplifier one by one. Therefore, the confirmation efficiency is low, and a lot of trouble, time, and cost are required to specify the noise generation point or the inflow point. For example, when n amplifiers are connected to the transmission line and the amplifier that is the actual noise generation or inflow point is the amplifier closest to the center, all (n ) Must check the amplifier. (2) In the above method (3), it is not necessary for an operator to go to each amplifier, but it is the same that each amplifier must be checked one by one. It takes effort, time and expense to specify.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to be able to easily and quickly specify a noise generation point or an inflow point in a CATV transmission network, and to automatically cut off an upstream transmission line simultaneously with the specification. Another object of the present invention is to provide a CATV device that can also prevent noise from flowing into the center.

The first CATV device of the present application is a bidirectional CATV.
CATV equipment such as a trunk amplifier, a branch amplifier, an extension amplifier, a distributor, a branching device, a security device, a branching device in a home, and a home amplifier used in a system, and a gate switch capable of blocking / releasing an upstream transmission path, A splitter for extracting a part of the uplink signal and noise propagating in the uplink transmission line, a band rejection filter for blocking the passage of the uplink signal, and a band rejection filter out of the uplink signal and noise extracted by the splitter, Comparing with a reference voltage of noise, when the output voltage is higher than the reference voltage, the gate switch is operated to cut off the upstream transmission path, and a comparator that constantly outputs a predetermined signal to the status monitor is provided. The status monitor to which is input is to transmit noise level information to the center.

In the second CATV device of the present application, the status monitor can change the pass rejection band of the band rejection filter based on a command from the center.

[0007] The third CATV device of the present application includes a comparator,
A voltage is output only when the output voltage of the detector exceeds the reference voltage and the difference is within a predetermined range, and when the output voltage of the detector exceeds the reference voltage, but the difference exceeds the predetermined range, It is set so as not to output a voltage.

[0008]

(Embodiment 1) An example of an embodiment of a CATV device according to the present invention will be described in detail with reference to FIG. The CATV equipment shown in the present embodiment is an extension amplifier connected to a branch line forming a relay transmission network of a bidirectional CATV system.

This extension amplifier has a downstream input terminal (up output terminal) 10 as shown in FIG.
And an upstream input terminal (downstream output terminal) 12. The downstream signal input to the downstream input terminal 10
Is distributed to the downstream transmission line 16 by the
The signal is amplified to a predetermined level by the upper amplification element 18 and output from the downstream output terminal 12. Also, the upstream input terminal 12
Is input to the upstream transmission line 1 by the demultiplexing filter 20, is amplified to a predetermined level by the amplifier 22 on the transmission line 1, and is output to the upstream output terminal 10.
Output from That is, it has the same configuration as the conventional extension amplifier and performs the same function.

Further, in addition to the above configuration, the extension amplifier of the present invention further comprises a gate switch 2 capable of blocking / releasing the upstream transmission line 1, a status monitor 3, and a status monitor 3, as shown in FIG.
A branching unit 4 for branching out and extracting a part of the upstream signal and noise propagating in the upstream transmission 1, and among the upstream signal and noise branched by the branching unit 4, blocking the passage of the upstream signal and passing only the noise A band rejection filter 5, an amplifying element 6 for amplifying noise passing through the band rejection filter 5, a detector 7 for outputting a voltage corresponding to the level of the noise amplified by the amplifying element 6, and an output voltage of the detector 7 Is compared with a reference voltage, and when the output voltage exceeds the reference voltage, a comparator 8 that outputs a predetermined voltage to the gate switch 2 and constantly outputs a predetermined voltage to the status monitor 3 is provided.
The gate switch 2 operates when a voltage is input from the comparator 8 to cut off the upstream transmission line 1. The status monitor 3 to which the voltage is input from the comparator 8 is connected to the upstream transmission line 1.
The information on the above noise level is transmitted to a center (not shown). Note that the comparator 8 is always the status monitor 3
Outputting a predetermined voltage does not necessarily mean that the voltage is output constantly, but means that the voltage is output at a predetermined timing regardless of the comparison result.

As described above, according to the extension amplifier of the present invention, when the level of noise generated or flowing into the extension amplifier exceeds a predetermined level, the upstream transmission line is automatically cut off and the noise is reduced. The noise is prevented from flowing into the center, and information indicating that the noise has exceeded a predetermined level is transmitted to the center, so that it is possible to immediately identify the noise generation location or the flow location.

The status monitor 3 shown in FIG. 1 can open and close the gate switch 2 irrespective of the presence or absence of an output from the comparator 8. By transmitting a signal from the center to the status monitor 3, the gate switch 2 can be turned on at any time. Can be opened and closed. Therefore, the gate switch 2 which has been opened or closed based on the output of the comparator 8 to shut off the upstream transmission line 1 eliminates the cause of noise generation or inflow, and then the status monitor 3 closes or opens the gate switch 2 to shut off the shutdown. Can be canceled.

The pass rejection frequency band of the band rejection filter 5 shown in FIG. 1 is naturally adapted to the frequency of the upstream signal, but the pass rejection frequency band can be arbitrarily changed. Specifically, when a signal is transmitted from the center to the status monitor 3, the status monitor 3 receives the signal.
Thus, the pass rejection frequency band of the band rejection filter 5 is changed. Further, the reference voltage of the comparator 8 can be arbitrarily changed, and the noise level at which the upstream transmission line 1 is cut off by the gate switch 2 can be arbitrarily set. Further, the comparator 8 includes a detector 7
Is output to the gate switch 2 only when the output voltage exceeds the reference voltage and the difference is within a predetermined range (for example, ○ dBμ to ○ dBμ), and the output voltage of the detector 7 However, when the difference exceeds the predetermined range, the voltage may not be output.
In this way, although the noise level is high, the gate switch 2 does not operate depending on the burst noise which suddenly occurs and disappears immediately.

Second Embodiment In the first embodiment, the case where the CATV equipment of the present invention is an extension amplifier has been described. However, the CATV equipment of the present invention includes the gate switch, the branching device, the band rejection filter, and the amplifying element. , Detector, comparator, mains amplifier, branch amplifier, distributor, with status monitor,
Various CATVs such as branch switches, protectors, branch switches at home, amplifiers at home, etc.
Equipment included. As close as possible to the end of the CATV transmission network
If a CATV device (for example, a branching device) is the CATV device of the present invention, it is possible to considerably narrow down a noise generation location or a flow-in location.

In the CATV equipment according to the present invention, the noise level is continuously monitored even after the upstream transmission line is cut off, and when the level falls below a predetermined level, the gate switch is automatically operated to cut off the upstream transmission line. It can also be canceled.

[0016]

The CATV device of the present application has the following effects. (1) When the level of noise generated in or flowing into the CATV equipment exceeds a predetermined level, the upstream transmission line is automatically cut off, so that the flow of noise into the center can be automatically stopped. it can. (2) Since the information indicating that the noise has exceeded a predetermined level is transmitted to the center at the same time as the interruption of the upstream transmission path, the location where the noise is generated or the location where the noise flows in the transmission network can be immediately specified at the center. . Therefore, as compared to the conventional method in which the upstream output of each device is sequentially cut off and the noise generation point or the inflow point is specified, the trouble, time, and
All of the costs are greatly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an embodiment of a CATV device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Up transmission line 2 Gate switch 3 Status monitor 4 Branching device 5 Band rejection filter 6 Amplifying element 7 Detector 8 Comparator

Claims (3)

[Claims] A CATV device such as a main line amplifier, a branch amplifier, an extension amplifier, a distributor, a branch device, a security device, a home branch device, and a home amplifier used in a bidirectional CATV system, wherein the upstream transmission line is provided. A gate switch (2) capable of shutting off and canceling the cutoff, a splitter (4) for extracting a part of the uplink signal and noise propagating in the uplink transmission line (1), and an uplink signal extracted by the splitter (4) And noise
A band rejection filter (5) for blocking passage of an upstream signal;
When the output voltage exceeds the reference voltage, the gate switch (2) is actuated to cut off the upstream transmission line (1), and the status monitor is constantly performed. (3) CATV equipment comprising a comparator (8) for outputting a predetermined signal, wherein the status monitor (3) to which the output of the comparator (8) is input transmits noise level information to the center. . 2. The CA according to claim 1, wherein the status monitor (3) is capable of changing a pass rejection band of the band rejection filter (5) based on a command from the center.
TV equipment. 3. The comparator (8) outputs a voltage only when the output voltage of the detector (7) exceeds the reference voltage and the difference is within a predetermined range, and outputs the voltage of the detector (7). 3. The CATV apparatus according to claim 1, wherein the voltage is set so as not to output the voltage when the voltage exceeds the reference voltage but the difference exceeds a predetermined range.