JP2525235Y2 - CATV system - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CATV (Television Joint Viewing) system having a function of maintaining and managing the quality of a broadcast signal received by a subscriber.

[0002]

2. Description of the Related Art Conventionally, in order to prevent deterioration of a television reception image in a mountain area, a building shadow, an underpass, etc.
CATV systems are widely used. Also, this C
The use of the ATV system has been increasing in recent years in order to provide various information services in a specific area. FIG. 2 shows a block diagram of a conventional CATV system. In this figure, a VHF antenna 1, a UHF antenna 2, and a satellite broadcast antenna 3 are all connected to a head end 4. The broadcast signal 10A is transmitted from the head end 4 to the hub 5 via the broadcast line 10. The broadcast signal 10A is distributed to each subscriber 7 by the relay amplifier 6 via the hub 5. The hub is a subscriber repeater that relays and processes a broadcast signal in this way.

[0003] The head end 4 has antennas 1,
A multiplexer 8 connecting the devices 2 and 3 and an E / O (electric-optical converter) 9 for converting the output of the multiplexer 8 into an optical signal are provided. The broadcast signal 10A thus converted into an optical signal is input to an O / E (optical-electrical converter) 11 provided in the hub 5 via the broadcast line 10. The output of the O / E 11 is output to the relay amplifier 6 described above via the branch coupler 12. Conventionally, coaxial cables have been widely used in CATV systems. However, the coaxial cable has a disadvantage that the attenuation is relatively large when transmitting a high-frequency signal over a long distance. Therefore, large CA
In a TV system, an optical fiber has been widely used to transmit a broadcast signal from a head end 4 to a hub 5 located close to a subscriber 7 as shown in FIG.

[0004] Here, in a large-scale CATV system, the quality of a signal received by a subscriber 7 is controlled by a head end 4.
The maintenance and management is done on the side. In this case, for example, an operation state signal 15A for constant operation state monitoring is output to the hub 5 from the relay amplifier 6 side. The operation state signal 15A is, for example, an encoded digital signal indicating whether or not each relay amplifier 6 is operating normally. The branch coupler 12 provided in the hub 5 outputs the operation state signal 15A to the E / O 13 provided in the hub 5. The operation state signal 15A is converted into an optical signal in the E / O 13, and the O / E 14 provided in the head end 4 via the monitoring line 15 composed of an optical fiber.
To enter. In the headend 4, the output of the O / E 14 is received by the monitoring unit 16, and the contents of the operation state signal 15A are displayed on a display, or output to a printer or the like as necessary to monitor the state. If the reception status deteriorates, the serviceman performs a procedure of checking each part of the system. As described above, the transmission of the broadcast signal 10A and the transmission of the operation state signal 15A use optical fibers, respectively.
A two-core optical fiber cable is employed as a whole.

FIG. 3 illustrates the flow of signals in the branch coupler 12. As shown in the drawing, in the conventional system, a broadcast signal 10A is transmitted from the O / E 11 to the relay amplifier 6 via the branch coupler 12. The broadcast signal 10A has a band of about 80 to 450 MHz for transmitting a signal for satellite broadcast from FM broadcast, for example.
On the other hand, the operation state signal 15A transmitted from the relay amplifier 6 to the head end is a signal having a band in the range of 10 to 50 MHZ, and is configured to be transmitted in the E / O 13 direction in the branch coupler 12. Conventionally, the system has been maintained and managed by the above configuration.

[0006]

In the conventional CATV system of this type, the operation state of the relay amplifier and other components constituting the system is grasped by the operation state signal 15A, so that the image on the subscriber side is indirectly obtained. Quality control was performed. However, it was difficult to know minute changes in image quality and abnormalities only with the operation state signal 15A. Therefore, there is a problem in that a technician must be actually dispatched to the site in response to the subscriber's complaint and the received image must be inspected before a specific failure diagnosis or the like is performed.

When an abnormality is found on the side of the head end 4, a technician is dispatched to deal with the abnormality and recover it. However, the subscriber receives the technician until the technician arrives and such a fault is recovered. There is also a problem that the user must wait for the image quality to recover. This invention has been made in view of the above points, more precisely monitor the state of the system, CA capable For switching as necessary to promptly spare line
It is intended to provide a TV system.

[0008]

According to a first aspect of the present invention, there is provided a main broadcast line for transmitting a broadcast signal from an upstream side to a subscriber repeater on a downstream side, and a main broadcast line arranged in parallel with the main broadcast line. It is a secondary broadcast channel for transmitting the broadcast signal same broadcast signal and the direction from the upstream side to the subscriber side repeater, what the main broadcast channel and the secondary broadcast channel in the subscriber-side repeater A switch for selecting one of them and transmitting the broadcast signal; and a subscriber side repeater for transmitting the broadcast signal via the switch.
While transmitting to the device of the broadcast signal further downstream to be signal branches the broadcast signal, and the combined and monitor signal the operating state signal to the broadcast signal indicating the operating state of the downstream side of the device A branch coupler for generating, a monitor line for receiving a monitor signal including the broadcast signal and the operation state signal from the branch coupler and transmitting the monitor signal to an upstream side of the main broadcast line, A monitoring unit that monitors the output, a line switching unit that is installed near the monitoring unit and outputs a switching control signal for controlling the selection operation of the switching unit, and outputs the switching control signal from the line switching unit to the line switching unit. The present invention relates to a CATV system comprising a control line for transmitting to a switch.

In a second aspect of the present invention, a main broadcast line for transmitting a broadcast signal from an upstream side to a subscriber repeater on the downstream side is provided, and the main broadcast line is provided in parallel with the main broadcast line. selection and secondary broadcast channel for transmitting the broadcast signal same broadcast signal and towards the subscriber side repeater, something Re of the outputs of said main broadcast channel and the secondary broadcast channel in the subscriber-side repeater switcher and the subscriber to send the broadcast signal to
The broadcast transmitted through the switch in the side repeater
While transmitting the transmission signal to the further downstream device,
To receive the operation status signal indicating the operation status of the device on the side
For monitoring the operating state signal from the coupler and the branch coupler
A monitoring unit that receives and monitors the upstream side of the main broadcast line via a line , and a switching control signal that is installed near the monitoring unit and controls a selection operation of the switch. And a control line for transmitting the switching control signal from the line switching unit to the switching unit.

[0010]

In this system, not only an operation state signal indicating the operation state from the receiving side but also a monitor signal 53 actually received by the receiving side and including a broadcast signal is transmitted to the upstream side. As a result, on the upstream side, the same image as that actually received by the subscriber is monitored using a television or the like, and detailed management of image quality is performed. In addition, a sub-broadcasting line is arranged in parallel with the main broadcasting line, and one line in which a fault has occurred is switched to the other line under control from the upstream side. As a result, detailed maintenance and quick recovery from a failure can be achieved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 is a system block diagram of the first invention of the present invention. The illustrated system includes a headend 20A to which a VHF antenna 1, a UHF antenna 2, a satellite broadcasting antenna 3 and the like are connected, a hub 30A, a relay amplifier 6, and a subscriber 7. Head end 20A and hub 3
In this embodiment, a three-core optical fiber cable is used to connect between 0A. That is, three optical fibers are used for the main broadcast line 41, the sub broadcast line 42, and the monitor line 43, respectively. It is also assumed that the cable further includes a control line 44 made of a metallic wire.

The head end 20A shown in FIG.
E / Os 22 and 23, O / E 24, monitoring unit 25 and line switching unit 26 are provided. The hub 30A is connected to the O /
E31, E32, switch 33, branch coupler 34 and E / O
35 is provided. The multiplexer 21 of the head end 20A
Is a circuit that combines output signals of the VHF antenna 1, the UHF antenna 2, and the satellite broadcast antenna 3 and outputs the combined signals to the E / Os 22 and 23. The E / Os 22 and 23 are circuits that convert this signal into an optical signal and output it to the main broadcast line 41 or the sub broadcast line 42, respectively. Hub 3
0A O / Es 31 and 32 are main broadcast lines 4 respectively.
1 or a broadcast signal 51 received from the sub broadcast line 42
Is a circuit that accepts and converts it into an electric signal. Switch 3
A switch circuit 3 receives the output signals of the O / Es 31 and 32, selects one of them, and outputs the selected signal to the branch coupler 34. The output of the branch coupler 34 is distributed to a number of subscribers 7 via the relay amplifier 6.

In the system of the present invention, an operation state signal 15A for transmitting the operation state is transmitted from the relay amplifier 6 to the branching coupler 34. The branch coupler 34 transmits this signal to the E / O 35 and sends it to the upstream side.

That is, in one CATV system, 10
0 or more relay amplifiers are installed
And assign a number corresponding to each of these relay amplifiers
Then, call the relay amplifier in the numerical order in the F Ddoendo side
You. In this case, use the main broadcast line, etc.
A ring signal using a specific frequency band within
You. As a result, the branch coupler 34 is connected to the corresponding relay amplifier.
The operation state signal 15A is sequentially received from the
To the host. The operation state signal 15A includes an additional relay.
Power supply voltage (DC and AC) of the band, input broadcast signal
Voltage, output broadcast signal voltage, amplifier lid opening and closing
(Use micro switch, etc.), other operation status
Signal component that indicates the state of the
At the head end. And f
The normal or abnormal level is predicted on the
This level is compared with the operation state signal 15A.
Will do. Here, in the system of the present invention,
The branch coupler 34 transmits the broadcast signal received from the switch 33 to the E / O 35 so as to be included in the monitor signal 53 as it is. The monitor signal 53 is transmitted to the monitor line 43
Is transmitted to the O / E 24 via the. On the upstream side, a monitoring unit 25 is provided in the head end 20A, and monitors a monitor signal output from the O / E 24. This makes it possible to monitor the operation state on the downstream side and the broadcast signal actually received on the downstream side using a television or the like, and to perform maintenance and management thereof.

The line switching unit 26 includes a head end 20
A is provided in the vicinity of the monitoring unit 25 of A
If any abnormality is found by the monitoring, the line switching unit 26 is operated to output the switching control signal 54 to the switch 33 via the control line 44. Switch 3
3 operates to switch the selection in accordance with the switching control signal 54. That is, the switch 33, which has accepted the output of the O / E 31 and outputs it to the branch coupler 34, branches the broadcast signal input via the sub-broadcasting line 42 and the O / E 32 by the switch control signal 54. It operates to output to the combiner 34. by this,
It is possible to quickly back up an abnormality in the main broadcast line 41 and circuits connected thereto.

FIG. 4 is a block diagram showing the operation of the branch coupler 34 shown in FIG. As shown in the figure, in the system of the present invention, while the broadcast signal 51 is transmitted from the switch 33 to the relay amplifier 6, the broadcast signal is branched by the branch coupler 34 and included in the monitor signal to be included in the E / O 35.
Transmitted to Further, the operation state signal 15 is transmitted from the side of the relay amplifier 6 to the E / O 35 via the branch coupler 34.
A is transmitted. The broadcast signal 51 is a signal in a band of 80 to 450 MHz, for example, from FM waves to satellite broadcast waves. The monitor signal 53 is 10 to 10 from the side of the relay amplifier 6.
The combined signal includes the operation state signal 15A of 50 MHZ. Therefore, in the E / O 35, the combined signal is converted into an electric signal and transmitted to the upstream side of the head end 20A via the monitoring line 43 shown in FIG.

FIG. 5 is a block diagram showing a specific example of the switch.
In the figure, the switch 33 shown in FIG. 1 and whose internal structure is shown in FIG. 4 includes, for example, a relay (RY) 33A and a driver 33B. Further, a switch (SW) 26A is provided in the line switching unit 26 in the head end 20A shown in FIG. Line switching unit 2
When the switch 26A of No. 6 is operated, the switching control signal operates the driver 33B via the control line 44.
As a result, the relay 33A is turned on and off, and the connection direction of the switch 33 is changed to O / E31 or O / E31 as shown in FIG.
It is switched to E32.

In order to perform such control, for example, the relay 3 flowing through the control line 44 by the switch 26A is used.
What is necessary is just to turn on and off the DC current for excitation of 3A. Alternatively, the electronic relay of the switch 33 may be controlled using a pulse-like digital control signal. Further, if a method of controlling by transmitting a constant pattern of AC signals in a burst form is employed, drift caused by fluctuation of a so-called bias signal is suppressed as compared with a case where a DC signal is supplied to the control line 44, for example. As a result, stable control becomes possible.

As described above, when the broadcast signal actually received on the downstream side is monitored on the television screen at the head end 20A (FIG. 1), the increase in noise mixed into the image, the occurrence of beats, etc. When an abnormality is found, one of the main broadcast line 41 and the sub broadcast line 42 is immediately switched to the other, and the technician can proceed with maintenance and recovery work while maintaining the quality of the transmitted image. . In this case, the system of the present invention uses a three-core optical fiber cable as compared with a conventional two-core optical fiber cable, which may increase the cost. However, when an optical fiber cable is normally used in this type of system, a cable structure having one or two spare core wires is always adopted. Therefore,
Even in the conventional case, such a number of spare core wires are provided, and the present invention can be implemented only by using such spare core wires. Further, the sub-broadcasting line 42 and the monitor line 43 can be integrated by bidirectional transmission of an optical signal.

FIG. 6 is a system block diagram of the second invention of the present invention. In the second invention , the branch coupler 34
A uses a circuit having the same configuration as that used in the conventional device. That is, the monitoring line 15 is configured to transmit only the operation state signal 15A to the monitoring unit 25A as in the conventional system. On the other hand, a main broadcast line 41 and a sub broadcast line 42 are provided between the head end 20C and the hub 30C, and a switch 33 similar to that described in FIG.
If one of the failures occurs, the other can switch the connection. The control of the switching unit 33 is performed via a control line 44 by a line switching unit 26 provided in the upstream head end 20C. As described above, by switching the switch 33 by remote control on the side of the headend 20C and switching the line in which the failure has occurred to the spare line, maintenance can be performed while always transmitting a high-quality signal to the subscriber. There is an effect that management can be performed.

The present invention is not limited to the above embodiment. In the above-described embodiment, the line switching unit and the monitoring unit are provided at the head end, and the switching unit and the branch coupler are provided at the hub 30C. However, the monitoring unit and the like are arranged at another place provided on the upstream side. Alternatively, a switch, a branch coupler, or the like may be provided in any downstream-side subscriber repeater. In addition, the configurations and block configurations of these circuits may be replaced with various circuits having similar functions.

[0022]

[Effect of the Invention] As described above, the CATV of the present invention is used.
The system transmits a monitor signal corresponding to the broadcast signal actually received on the downstream side from the downstream side to the upstream side, and monitors the monitor signal on the upstream side. Sufficient maintenance can be performed by performing detailed diagnosis. In addition, if a main broadcast line and a sub broadcast line are provided and the line is duplicated and the connection of the line can be switched by a line switching unit provided on the upstream side, one of the lines has an abnormality. If
The connection can be promptly switched to the other line, and the restoration of a failure can be performed while maintaining the quality of the broadcast signal.

[Brief description of the drawings]

FIG. 1 is a system block diagram of a first device of the present invention.

FIG. 2 is a block diagram of a conventional CATV system.

FIG. 3 is an explanatory diagram of a transmission signal of a conventional system.

FIG. 4 is an explanatory diagram of a transmission signal of the system of the present invention.

FIG. 5 is a block diagram of a specific example of a switch.

FIG. 6 is a system block diagram of the second invention.

[Explanation of symbols]

 Reference Signs List 25 monitoring unit 26 line switching unit 33 switch 34 branch coupler 41 main broadcast line 42 sub broadcast line 43 monitor line 44 control line 51 broadcast signal 53 monitor signal 54 switching control signal

Claims (2)

(57) [Scope of request for utility model registration] A main broadcast line for transmitting a broadcast signal from an upstream side to a downstream side subscriber repeater; a main broadcast line provided in parallel with the main broadcast line; transmitting a secondary broadcast channel for transmitting the broadcast signal same broadcast signal and toward, the broadcast signal by selecting what Re of the main broadcast channel and the secondary broadcast channel in the subscriber-side repeater A switch, which is transmitted via the switch at the subscriber-side repeater.
While transmitting to the device of the broadcast signal further downstream that branches the broadcast signal, and generates a monitoring signal by combining the operation state signal indicating the operating state of the downstream side of the apparatus to the broadcast signal A branch coupler, a monitor line that receives a monitor signal including the broadcast signal and the operation state signal from the branch coupler and transmits the monitor signal upstream of the main broadcast line, and an output of the monitor line. A monitoring unit for monitoring, a line switching unit installed near the monitoring unit for outputting a switching control signal for controlling a selection operation of the switching unit, and a switching unit for transmitting the switching control signal from the line switching unit to the switching unit. A CATV system comprising: a control line for transmitting data to a computer. 2. A main broadcast line for transmitting a broadcast signal from an upstream side to a downstream subscriber side repeater; a secondary broadcast channel for headed transmitting the same broadcast signal and the broadcast signal, the broadcast signal by selecting what Re of the outputs of said main broadcast channel and the secondary broadcast channel in the subscriber-side repeater transmission of through the switching device in the switching device to transmit, the subscriber-side repeater
Transmitting the broadcast signal to a downstream device.
On the other hand, an operation state signal indicating the operation state of the downstream device is
A branch coupler to be received, and an operation state signal from the branch coupler through a monitoring line.
A monitoring unit for receiving the upstream side of the main broadcast channel, and monitors Te, and the placed in the vicinity of the monitoring unit, the line switching unit for outputting a switching control signal for controlling the selecting operation of the switching device And a control line for transmitting the switching control signal from the line switching unit to the switching unit.