JP2532157B2 - Relay amplifier for bidirectional CATV system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a relay amplifier of a bidirectional CATV system capable of monitoring an operating state on the side of a center device.

[Prior Art] A relay amplifier of this type is provided on a transmission line from a center device to a terminal device and includes an amplification unit for amplifying a transmission signal and a power supply unit for supplying power to the amplification unit. There is something.

Further, in recent years, in order to allow the center device side to monitor the operating states of these units, the amplification unit and the power supply unit are
There is also one in which various detecting devices for detecting the operating state thereof are provided so that the detection result can be transmitted to the center side device in response to a command from the center device side.

[Problems to be Solved by the Invention] By the way, the conventional relay amplifier which communicates with the center device as described above includes a high-frequency modem in the amplification unit and the power supply unit, respectively, and communicates with the center device by the amplification unit and the power supply. In a large-scale CATV system that uses a large number of relay amplifiers of this type, the number of connection points between the transmission line and the high-frequency modem increases, and the number of connection points increases as the number of connection points increases. There was a problem that good communication could not be performed due to ingress noise.

Therefore, the present invention suppresses the occurrence of ingress noise and reduces the
It was made for the purpose of providing a relay amplifier for a bidirectional CATV system that can be used well in a CATV system.

[Means for Solving the Problem] That is, the present invention made to achieve the above object is provided on a transmission line from a center device to a terminal device, and amplifies and outputs a transmission signal flowing through the transmission line. A relay amplifier of a bidirectional CATV system comprising an amplification unit and a power supply unit which is formed separately from the amplification unit and supplies power to the amplification unit, wherein the amplification unit is provided with the transmission line. A high frequency modem for performing data communication with the center device, an amplifier state detection means for detecting the operating state of the amplifier, and a command signal from the center device demodulated by the high frequency modem, When the command signal is a command to output the status signal to the amplification section, the status signal obtained by the amplification section status detection means is output to the high frequency modem, and the status is output from the high frequency modem. An amplification unit state transmission control unit for transmitting a transmission signal in which a carrier wave is modulated by a signal to the center device, the power supply unit state detection unit for detecting an operation state of the power supply unit, and the high frequency The command signal from the center device demodulated by the modem is taken in, and when the command signal is an output command of the status signal to the power supply unit, the status signal obtained by the power supply unit status detection means is sent to the high frequency modem. Power supply unit state transmission control means for outputting and transmitting to the center device a transmission signal obtained by modulating a carrier wave with the state signal from the high frequency modem, and further, the amplification unit and the power supply unit, respectively. A state in which a command signal from the center device demodulated by the high frequency modem is transferred to the power supply unit status transmission control unit and output from the power supply unit status transmission control unit. The characterized in that a transmission means for transferring the RF modem No..

[Operation and Effect of the Invention] In the relay amplifier of the present invention configured as above, when the command signal is transmitted from the center device, the high frequency modem provided in the amplifying section receives the command signal and demodulates it. . Then, the demodulated command signal is input to the amplification unit state transmission control unit in the amplification unit and also to the current unit state transmission control unit in the power supply unit via the transmission unit.

On the other hand, in the amplification unit, the amplification unit state detection means detects the operation state of the amplification unit, and in the power supply unit, the power supply unit state detection unit detects the operation state of the power supply unit. If it is a command to output the status signal to the amplifier, the amplification unit status transmission control unit determines that, and outputs the status signal obtained by the amplification unit status detection unit to the high frequency modem, thereby A transmission signal obtained by modulating a carrier wave with a status signal is transmitted to the center device.

If the command signal from the center device is a status signal output command to the power supply unit, the power supply unit status transmission control means
By making a determination to that effect and outputting the status signal obtained by the power supply status detecting means to the high frequency modem via the transmitting means, the center apparatus transmits a transmission signal obtained by modulating a carrier wave with the status signal from the high frequency modem. To send.

That is, the relay amplifier of the present invention, when the output signal of the status signal is issued from the center device to the relay amplifier,
In response to the command, a state signal indicating the operating state of the amplification section or the power supply section is transmitted to the center device side. It realizes so-called polling type data communication. In the present invention, the high-frequency modem for performing data communication with the center device is not provided individually in the amplification section and the power supply section as in the conventional case, but is provided only in the amplification section side. The number of connection points between the transmission line of the entire system and the high-frequency modem is reduced, and the ingress noise that increases as the number of connection points increases is reduced.

Therefore, according to the present invention, it is possible to prevent communication failure in the CATV system due to the occurrence of such ingress noise, and since it is not necessary to provide a high frequency modem in the power supply unit, a relay amplifier, and by extension, a CATV. The cost of the system can be reduced.

Further, according to the relay amplifier of the present invention, the amplification of the detection of the operating states of the amplification unit and the power supply unit, the determination of the output instruction of the state signal from the center device side, and the output of the state signal corresponding to the output instruction are performed. By the detection means (amplifier state detection means, power source state detection means) and transmission control means (amplifier state transmission control means, power source state transmission control means) provided in the power supply section and the power supply section, respectively. It is supposed to be done individually by the side.

Therefore, for example, even if one of the transmission control means (amplification unit status transmission control means or power supply status transmission control means) of the amplification section and the power supply section fails, the operation on the side where the transmission control means does not fail The state can be normally monitored on the side of the center device, and system restoration work and the like can be performed accurately and quickly.

As described above, according to the present invention, the detection of the operating state and the output of the state signal on the power supply unit side are performed independently of the amplification unit, and are demodulated by the high frequency modem. Since the transmission means for data transfer is separately used for inputting the command signal from the center device to the power supply unit and outputting the status signal from the power supply unit to the high frequency modem, it is transmitted to the center device side. Even if the operating state of the power supply unit to be increased, the number of signal lines connecting the amplification unit and the power supply unit does not increase, and the installation work of the relay amplifier and the like can be easily performed.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 2 shows a bidirectional CATV of an embodiment to which the present invention is applied.
It is a schematic structure figure showing the composition of the whole system.

In the figure, 1 represents a head end that receives and processes a television signal and the like, and a transmission signal output from the head end 1 is sent to a terminal side via a center device 3. Further, on the trunk line 5 from the center device 3 to the terminal side, the trunk line branch amplifiers 7A, 7B, 7C as amplification units for bidirectionally amplifying the transmission signal flowing through the trunk line 5 and branching to the terminal side in each area. Are provided, and each of the trunk line branch amplifiers 7A, 7B, 7C ... Is provided with a power supply device 9A, 9B, 9C.

The center device 3 includes the trunk branch amplifiers 7A, 7B, 7C,
..., various signals such as pay television signals transmitted to the terminal device T of the facility via the branching device DC, the distributor SP, etc., via the branching circuit 10 and the branching device 11, as shown in FIG. 5 is provided with a signal generating device 12 for outputting to the main line branch amplifiers 7A, 7B, 7C, ... Or power supply devices 9A, 9B, 9C. A status signal output command is issued, whereby the status signal transmitted from the trunk branch amplifiers 7A, 7B, 7C, ... Or the power supply devices 9A, 9B, 9C ... Is passed through the branching device 11 and the branching circuit 10. A state monitor 13 for receiving and displaying the operating states of the trunk line branch amplifiers 7A, 7B, 7C, ... And the power supply units 9A, 9B, 9C.

The state monitoring device 13 includes an electronic control circuit 14 for executing various processes for state monitoring, and a keyboard 15 for inputting data and various commands necessary for executing the state monitoring process in the electronic control circuit 14. And a CRT 16 for displaying the operating state of each of the above parts, an external recording device 17 for recording the operating state on a disk as necessary, and a command signal output from the electronic control circuit 14 is modulated and sent to the main line 5. FSK modulation circuit 1
8 and FM modulator circuit 19, PSK which demodulates the status signal sent on trunk line 5 from trunk line branch amplifiers 7A, 7B, 7C, ... And power supply devices 9A, 9B, 9C. Demodulation circuit 20
It consists of and. The electronic control circuit 14 includes CPUs 14a, R
The OM14b, the RAM14c, the input / output port 14d and the like are configured as a well-known logical operation circuit.

Next, the trunk line branch amplifiers 7A, 7B, 7C, ...
As shown in the figure, the demultiplexing circuit 21a for demultiplexing the transmission signal flowing on the trunk line 5 into the transmission signal in the down direction (from the center device 3 to the terminal side) and the transmission signal in the up signal (from the terminal to the center device 3 side), 21b and a trunk line downstream amplification circuit 22 for amplifying the downstream transmission signal demultiplexed by the demultiplexing circuits 21a and 21b.
And a trunk line upstream amplification circuit 23 that amplifies the upstream transmission signal demultiplexed by the demultiplexing circuits 21a and 21b.

The main line down amplification circuit 22 is provided with two types of amplification circuits, a main line down main amplification circuit 22a that operates at DC24V 800mA and a main line down auxiliary amplification circuit 22b that operates at DC 24V400mA. Occurs, or when normal power supply cannot be performed due to an abnormality in the power supply system, the downlink amplification changeover switches 22c and 22d operate the trunk downlink auxiliary amplification circuit 22b with low power consumption to amplify the transmission signal. It can be output. Further, the trunk line up amplification circuit 23 is provided with a path circuit 23b that allows the transmission signal in the up direction to pass as it is, in addition to the trunk line up main amplification circuit 23a that operates at DC 24V 300 mA, and like the trunk line down amplification circuit 22, When an abnormality occurs in the amplifier circuit 23a or when normal power supply cannot be performed due to an abnormality in the power supply system, the upstream amplification changeover switches 23c and 23d switch the passing path of the upstream transmission signal to the path circuit 23b side. Has been made possible.

Further, the transmission signal flowing on the trunk line 5 is sent to the branch line 5a to each of the trunk line branch amplifiers 7A, 7B, 7C, ..., Via the branching device DC or the distributor SP provided on the branching line 5a. A branch circuit 24 and a branch amplifier circuit 25 are provided so as to be transmitted to the terminal device T, and further, the main line branch amplifiers 7A, 7B, 7C receive the power supply voltages output from the respective power supply devices 9A, 9B, 9C. A constant voltage circuit 27 for converting the power supply voltage supplied from each power supply device 9A, 9B, 9C ... into the operating voltage (DC 24V) of each amplification circuit is provided to operate the power supply devices.

The constant voltage circuit 27 is provided with two types of constant voltage circuits, a main constant voltage circuit 27a capable of supplying a power of 24V DC 1700mA and a sub constant voltage circuit 27b capable of supplying a power of 24V DC 400mA.
An abnormality occurs in the main constant voltage circuit 27a, the power supply device 9A,
When the commercial power supply fails on the 9B, 9C ... side, the constant voltage circuit changeover switch 27c can switch the constant voltage circuit used for power supply to the sub constant voltage circuit 27b.

The main constant voltage circuit 27a supplies power to the main line down amplification circuit 22, the main line up amplification circuit 23, the branch amplification circuit 25, and an operation state detection circuit 30 described later, and the sub constant voltage circuit 27b supplies the branch amplification circuit 25. Power is supplied to each of the above-mentioned units except the above.

Furthermore, the operating states of the power supply devices 9A, 9B, 9C ... and the operating states of the main line branch amplifiers 7A, 7B, 7C ,. An operation state detection circuit 30 for transmitting the detection result to the state monitoring device 13 of the center device 3 via the main line 5 and for switching the various changeover switches is provided.

The operation state detection circuit 30 receives a transmission signal branched from the output side of the trunk line down amplification circuit 22 via the branch circuit 31, and demodulates the command signal output from the state monitoring device 13 of the center device 3 to an FM demodulation circuit. 32 and FSK demodulation circuit 33, and the lid of the housing (hereinafter, referred to as a lid) in which the trunk line branch amplifiers 7A, 7B, 7C, ... Are not completely closed OF
The switch 34 for lid open detection in the F state, the ON / OFF state of this switch 34, and the above-mentioned amplifier circuits 22a, 22b, 2
Main line branch amplifiers 7A, 7B, 7C, ... Based on the AGC signal of the AGC circuit provided in 3a, 25, or the AC voltage from the power supply devices 9A, 9B, 9C. And a state signal generation circuit 35 that detects the operating states of the power supply devices 9A, 9B, 9C ... And outputs the detection result as a state signal, and that executes various control measures for switching the various changeover switches. A PSK modulation circuit 36 that PSK-modulates the status signal output from the signal generation circuit 35, and sends the status signal output from the PSK modulation circuit 36 to the branch circuit 37 provided on the input side of the trunk line down amplification circuit 23, And a gate circuit 38 for sending a status signal onto the trunk line 5.

In this embodiment, the FM demodulation circuit 32, FSK demodulation circuit 33 and PS
The K modulation circuit 36 corresponds to a high frequency modem.

Next, the status signal generation circuit 35, as shown in FIG.
It is configured as a well-known logical operation circuit centered on 5a, ROM 35b, and RAM 35c.

In addition, the status signal generation circuit 35 includes power supply devices 9A, 9B, 9C.
A rectifier circuit 35d for converting the power supply voltage supplied from the ... into a DC voltage is provided, and the power supply voltage levels from the power supply circuits 9A, 9B, 9C ... 22a, 22b, 23a, 25 AGC signal level,
Alternatively, the DC voltage level from the constant voltage circuit 27 can be input via the analog input port 35e equipped with an A / D converter.

Further, the state signal generating circuit 35 includes a resistor Ri for applying a DC voltage from the constant voltage circuit 27 to the switch 34 so that the open / closed state of the lid can be detected as a voltage signal, and a power supply device.
A power failure detection circuit 35 that detects the power failure status of the commercial power supply on the power supply device side from the power supply voltage waveforms supplied from 9A, 9B, 9C ...
An address setting circuit 35g for setting an address assigned in advance for each f and each of the trunk line branch amplifiers 7A, 7B, 7C, ... Is provided, and a detection signal indicating the open / closed state of the switch 34 obtained by the resistor Ri, a power failure detection Detection signal output from the circuit 35f indicating the power failure of the commercial power supply, address setting circuit 35g
The address of the trunk branch amplifier set by the above and the command signal from the state monitoring device 13 demodulated by the FSK demodulation circuit 33 can be input through the digital input port 35h.

In addition, the status signal generation circuit 35 includes a downstream amplification changeover switch.
22c and 22d, upstream amplification changeover switches 23c and 23d, and constant voltage circuit changeover switch 27c, respectively, output control signals to switch the main and sub parts of the amplification circuit and the constant voltage circuit, and to change the PSK.
An output port 35i is provided for outputting a status signal and a gate drive signal to the modulation circuit 36 and the gate circuit 38, respectively, and opening the gate circuit 38 to send the status signal onto the trunk line 5.

In addition, from the output port 35i to the PSK modulation circuit 36 and the gate circuit 38
The OR circuits 35j and 35k are provided in the signal paths to the PSK modulation circuit 36 and the gate circuit 38 via the OR circuits 35j and 35k, and the power supply devices 9A, 9B, 9C ... A signal and a gate drive signal can also be input.

That is, the state signal generation circuit 35 transmits a command signal from the state monitoring device 13 demodulated by the FSK demodulation circuit 33 to the power supply devices 9A, 9B, 9C ... EI that receives the status signal and the gate drive signal transmitted from the power supply devices 9A, 9B, 9C ... In response to the command signal from the line driver 351 and the status monitoring device 13, respectively.
Well-known receivers 35m and 35n compliant with the A-RS422A standard are provided, and a command signal from the state monitoring device 13 is transmitted to the power supply devices 9A, 9B, 9C ...
The status signal and the gate drive signal from the B, 9C ... side are input to the PSK modulation circuit 36 and the gate circuit 38, and the power supply devices 9A, 9
The status signals from the B, 9C ... Sides can be sent out on the trunk line 5.

Therefore, by addressing the command signal from the state monitoring device 13, the address setting circuit 35g of the trunk line branch amplifiers 7A, 7B, 7C ... Or the address setting circuit 6 of the power supply devices 9A, 9B, 9C.
A gate drive signal and a status signal are sent from OR circuit 35j and 35k from status signal generation circuit 35 or 60 (refer to FIG. 6 described later) that matches the address of 0e (refer to FIG. 6 described later). This status signal is transmitted to the center device 3.

Next, the power failure detection circuit 35f includes a rectifier circuit 35o for half-wave rectifying the power supply voltage from the power supply devices 9A, 9B, 9C.
From the output signal level from 5o is higher than the preset first reference level V1, the comparator 35p which outputs a high level signal, the integration circuit 35q which integrates the output signal from the comparator 35p, and the integration circuit 35q When the output signal level of is higher than the preset second reference level V2, Hi
It is composed of a comparator 35r that outputs a gh level signal, and a monostable multivibrator 35s that operates by an output signal from the comparator 35r.

That is, as will be described later in detail, each power supply device 9A, 9B,
9C ... is a sine wave AC commercial power supply that steps down to supply power to each trunk branch amplifier 7A, 7B, 7C ... If the commercial power fails, the DC voltage from the storage battery 45 is converted to an AC voltage and each trunk line Since the branch amplifiers 7A, 7B, 7C ... Are supplied with power, the main branch branch amplifiers 7A, 7B, 7C ... Are supplied with a sine wave alternating current as shown in FIG. As the power supply voltage, a rectangular wave AC power supply voltage as shown in FIG. 5 (a-2) is supplied when the commercial power supply fails. Therefore, in the power failure detection circuit 35f, when the commercial power supply is normal, the pulse signal as shown in FIG. 5 (b-1) is output from the comparator 35p and the output signal level from the integration circuit 35q is the fifth level.
It becomes a figure (c-1), and it becomes a figure 5 (d-1) and (e-.
As shown in 1), no signal is output from the comparator 35r and the monostable multivibrator 35s, and conversely, when the commercial power supply is interrupted, the comparator 35p outputs a pulse signal as shown in FIG. The output signal level from the circuit 35q is as shown in FIG. 5 (c-2), the pulse signal is output from the comparator 35r as shown in FIG. 5 (d-2), and the monostable multivibrator 35s is shown in FIG. As shown in (e-2), a high level signal is output.

The power failure detection circuit 35f may be composed of a rectifier circuit and an A / D converter instead of the above configuration, and the power failure state may be detected by the processing of the CPU 35a. That is CPU3
In 5a, by judging the power failure / uninterrupted from the magnitude of the time width when the A / D conversion value of the A / D converter becomes a predetermined value or more,
You may make it detect a power failure state.

Further, in the present embodiment, as the amplification unit state detection means for detecting the operation state of the amplification unit side, the switch 34 for lid open detection, A provided in each amplification circuit 22a, 22b, 23a, 25
Examples include a GC circuit, a rectifier circuit 35d that rectifies the power supply voltage, and a power failure detection circuit 35f. Further, in the present embodiment, the status signal generation circuit 35 corresponds to the amplification section status transmission control means of the present invention.

Next, the power supply devices 9A, 9B, 9C ...
From a commercial power source 43 that steps down the commercial power source input via the AC plug 41 and the breaker 42 to a predetermined voltage (for example, AC 60 V) and outputs, and a storage battery 45 and a storage battery 45 to which the commercial power source is charged by the charging circuit 44. An emergency power supply 47 equipped with an inverter 46 that converts a DC voltage into a predetermined voltage (for example, AC 60V) and outputs it, and a power failure detection circuit 48 that detects a power failure of the commercial power supply from the output voltage of the power supply 43. The output voltage from the power supply 43 is supplied to the main branch amplifiers 7A, 7B, 7C, ... When the power failure detection circuit 48 detects a power failure of the commercial power supply.
A switching circuit 49 for supplying the output voltage from 47 to the main branch amplifiers 7A, 7B, 7C ... Is configured as an uninterruptible power supply device. The emergency power supply 47 includes a temperature sensor 50 for detecting the temperature of the storage battery 45 and an inverter connected from the storage battery 45.
A current detection circuit 51 for detecting the current flowing through 46 is provided.

Further, each power supply device 9A, 9B, 9C ... has a power failure detection circuit 4
8, read the output signal from the temperature sensor 50, and the current detection circuit 51 as data representing the operating state of the power supply device,
A state signal generation circuit 60 is provided for generating the data as a state signal in response to a state signal output command from the state monitoring device 13 provided in the center device 3.

The state signal generating circuit 60 is a state monitoring device 13 transmitted from the line driver 35l of the trunk line branch amplifiers 7A, 7B, 7C ...
When the receiver 60a compliant with the EIA-RS422 standard for receiving the command signal from the power supply device 9A, 9B, 9C ... Is the output command of the status signal to the power supply device 9A, 9B, 9C. 48, temperature sensor 50, and the power supply device 9A, 9B, based on the output signal from the current detection circuit 51,
9C ... An electronic control circuit 62 that outputs a state signal and a gate drive signal that indicate the operating state, and a main branch amplifier 7 that outputs the state signal and the gate drive signal output from the electronic control circuit 62, respectively.
EIA-RS422A transmitting to receivers 35m and 35n for A, 7B, 7C ...
The line drivers 60b and 60c conforming to the standard, the detection signals from the temperature sensor 50 and the current detection circuit 51, or the storage battery 45
Electronic control circuit that converts the output voltage from the
A / D converter 60d input to 62 and power supply devices 9A, 9B, 9C ...
It is composed of an address setting circuit 60e for setting an address assigned for each.

The electronic control circuit 62 is configured as a logical operation circuit centering on the CPU 62a, ROM 62b, RAM 62c, input / output port 62d and the like.

Although not shown, the breaker 42 is provided with a sensor for detecting its on / off state and an electromagnetic switch for returning from the off state to the on state.
The input / output port 62d of the electronic control circuit 62 is also connected to each of these parts, and the electronic control circuit 62 side determines whether or not the breaker 42 is turned off at the time of a commercial power failure, and displays the determination result. At the same time as transmitting to the monitoring device 13 side, processing for returning the breaker 42 to the ON state by the command signal transmitted from the state monitoring device 13 side is also executed.

Incidentally, in the present embodiment, the power supply state detecting means for detecting the operating state of the power supply side, the power failure detection circuit 48,
A temperature sensor 50, a power supply detection circuit 51, and the like are included. Further, in the present embodiment, the state signal generation circuit 60 corresponds to the power supply unit state transmission control means of the present invention, and the main branch amplifier 7A, 7B,
7C ... side line driver 35l and receivers 35m and 35n,
The receiver 60a and the line drivers 60b, 60c on the side of the power supply devices 9A, 9B, 9C ... And the signal lines connecting these driver / receivers correspond to the transmission means of the present invention.

As described above, in the CATV system of this embodiment,
When the status monitoring device 13 provided in the center device 3 issues a status signal output command to a specific device such as the trunk line branch amplifiers 7A, 7B, 7C, ... Or the power supply devices 9A, 9B, 9C. A status signal representing the operating status is output from the device corresponding to the output command. Therefore, the operation state of each of these parts can be monitored on the side of the center device 3.

Further, the output of the command signal from the main line 5 to the power supply devices 9A, 9B, 9C ... and the output of the status signal from the power supply devices 9A, 9B, 9C ... to the main line 5 are the main line branch amplifiers 7A, 7B, 7C ... Is performed via a high frequency modem including an FM demodulation circuit 32, an FSK demodulation circuit 33, and a PSK modulation circuit 36 provided in the. Therefore, in order to communicate with the state monitoring device 13, the power supply device 9
There is no need to install expensive high-frequency modems in A, 9B, 9C ...
While simplifying the configuration of the power supply devices 9A, 9B, 9C ...
Cost can be reduced.

In addition, a state monitoring device for monitoring the on / off state of the breaker 42 provided in the commercial power supply path to the power supply devices 9A, 9B, 9C ...
When the breaker 42 is in the off state, the breaker 42 can be returned to the on state by a command from the state monitoring device 13 side. In such cases,
It is possible to restore the power supply devices 9A, 9B, 9C ... to a normal state without going to the installation place of the power supply devices 9A, 9B, 9C.

In the present embodiment, the main branch amplifiers 7A, 7B, 7C ... Send command signals from the status monitoring device 13 to the power supply devices 9A, 9B, 9C ..., and branch from the power supply devices 9A, 9B, 9C. amplifier
EIA-RS422A for sending status signals to 7A, 7B, 7C ...
The line driver and receiver conforming to the standard are used, but the main branch amplifiers 7A, 7B, 7C ... and the power supply devices 9A, 9B,
If the separation distance from 9C is short, communication can be performed without problems even if a line driver and receiver that comply with the EIA-RS232C standard are used.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a circuit configuration of a status signal generation circuit provided in a trunk branch amplifier of the embodiment, FIG. 2 is a schematic configuration diagram showing an overall configuration of a bidirectional CATV system of the embodiment, and FIG. FIG. 4 is a configuration diagram showing the circuit configuration of the center device, FIG. 4 is a configuration diagram showing the circuit configuration of the main branch amplifier, FIG. 5 is a time chart showing the operation of the power failure detection circuit provided in the main branch amplifier, and FIG. A configuration diagram showing a circuit configuration of a power supply device,
Is. 3 …… Center device, 5 …… Main line 7A, 7B, 7C …… Main line branch amplifier 9A, 9B, 9C …… Power supply device 32 …… FM demodulation circuit, 33 …… FSK demodulation circuit 36 …… PSK modulation circuit, T ... Terminal device 35,60 ... State signal generation circuit 35l, 60b, 60c ... Line driver 35m, 35n, 60a ... Receiver

Claims (1)

(57) [Claims] 1. An amplification unit provided on a transmission line from a center device to a terminal device, for amplifying and outputting a transmission signal flowing through the transmission line, and the amplification unit are formed separately, and the amplification unit is provided. A relay amplifier of a bidirectional CATV system comprising: a power supply unit for supplying power to a high-frequency modem for performing data communication with the center device via the transmission line, and the amplification unit. An amplifying section state detecting means for detecting an operating state of the section, and a command signal from the center device demodulated by the high frequency modem, and when the command signal is an output command of a state signal to the amplifying section, The status signal obtained by the amplifier status detection means is output to the high frequency modem,
An amplification unit state transmission control unit for transmitting a transmission signal obtained by modulating a carrier wave by the state signal from the high frequency modem to the center device, and the power supply unit state for detecting the operation state of the power supply unit in the power supply unit. A state obtained by the power source unit state detecting unit when a command signal from the center unit which is demodulated by the detecting unit and the high frequency modem is taken in and the command signal is an output command of a state signal to the power source unit. A power supply unit state transmission control means for outputting a signal to the high frequency modem and transmitting a transmission signal obtained by modulating a carrier wave with the state signal from the high frequency modem to the center device. The command signals from the center device demodulated by the high-frequency modem are transferred to the power supply units, and transferred to the power supply unit status transmission control means to transmit the power supply unit status. Bidirectional, characterized in that a state signal outputted from the control means provided with a transmission means for transferring the RF modem
CATV system relay amplifier.