JP2005020082A - Two-way catv amplifier and two-way catv system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate installation of a pilot signal generator 21 monitoring the state of a signal of an uplink line and to transmit a pilot signal to the uplink line by a simple and inexpensive method. <P>SOLUTION: The two-way CATV amplifier 3 provided with a status monitor unit 18 includes the pilot signal generator 21 for outputting a high frequency signal with an uplink band to the uplink line of the CATV system and the pilot signal being the high frequency signal with the uplink band outputted from the pilot signal generator 21 is transmitted to the uplink line via the status monitor unit 18. With the use of the two-way CATV amplifier 18, the two-way CATV system is constituted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bidirectional CATV amplifying apparatus provided with a pilot signal generator for outputting a signal of an upstream band frequency on an uplink of a bidirectional CATV system, and a bidirectional CATV system using the bidirectional CATV amplifying apparatus.
[0002]
[Prior art]
In the bidirectional CATV system, it is necessary to test and adjust not only the downlink but also the uplink. For this test / adjustment, it is necessary to transmit a reference signal to the line, monitor the state of the signal, and operate stably. Further, for example, in the case of a Hybrid Fiber Coaxial (HFC) system, a node type optical transceiver used in this system generates noise at the time of no modulation due to the characteristics of the laser diode used therein. Therefore, in a system in which cells are subdivided to increase the speed of the CATV network and the number of installed node type optical transceivers is increased, the node type optical transceivers and the like when the upstream signal becomes unmodulated. May increase the noise level transmitted to the upstream band from the center device and cause interference on the center device side.
Therefore, in the conventional bidirectional CATV amplifying apparatus, a pilot signal generator that transmits a signal of an upstream band frequency is incorporated in the uplink of the CATV system as necessary, and generation of noise is suppressed by a pilot signal output from now on. It is possible to attach a bidirectional CATV amplifier represented by such a node type optical transceiver to the transmission line of the bidirectional CATV system, and to send a pilot signal from the amplifier to the uplink of the transmission line. Therefore, if a measuring instrument such as a spectrum analyzer is connected to the upstream side of the line, the amplifier that sends the signal and the uplink in the section where the measuring instrument is connected are tested and adjusted. You can also do things. (For example, see Patent Document 1)
[0003]
[Patent Document 1]
JP-A-7-222136
[0004]
[Problems to be solved by the invention]
However, according to the bidirectional CATV amplifying device incorporating the conventional pilot signal generator, the upstream frequency signal output from the signal generator incorporated in the bidirectional CATV amplifying device passes through the switching circuit. The system can be turned ON / OFF on the upstream line of the system, and the switching circuit is switched manually or by controlling the switching control device (in other words, the status monitor unit) automatically by remote control from the center. To do. However, in such a configuration, the status monitor unit transmits a high-frequency signal to transmit a control signal sent from the center side to the status monitor unit and to transmit information from the status monitor unit to the center side. In addition, it is necessary to combine the signals of the upstream band frequency signal transmitted from the signal generator by providing a coupling circuit in the upstream line and mixing the signals. There is a problem that the configuration becomes complicated and the cost increases due to an increase in assembly cost.
In addition, the method of providing a circuit for coupling the signal from the pilot signal generator on the uplink requires the correspondence of amplifiers having different standards such as the degree of amplification, and it is necessary to design the circuit for the number of models. There has been a problem that circuit design becomes complicated. In addition, when adding a pilot signal generator to an existing bidirectional CATV amplifier, it is necessary to change the circuit in order to insert a coupling circuit. There was also a problem that it was difficult.
Therefore, the present invention has been made to solve the above-mentioned problems of the prior art,
An object of the present invention is to provide a bidirectional CATV amplifier capable of preventing an increase in noise level when an unmodulated signal is input to an uplink.
Another object is to provide a bidirectional CATV amplifying apparatus capable of outputting a signal that can be used for testing and adjusting an uplink of a CATV system.
Another object of the present invention is to provide a bidirectional CATV amplifying apparatus in which a pilot signal generator for outputting a signal having a frequency in the upstream band is incorporated in the upstream line of the CATV system.
Another object of the present invention is to provide a bidirectional CATV amplifying apparatus that can transmit an upstream band frequency signal to an upstream line of a CATV system with a simple configuration.
Another object of the present invention is to provide a bidirectional CATV amplifying apparatus that makes it possible to attach a pilot signal generator freely and to easily supply a pilot signal correspondingly.
Another object of the present invention is to provide a bidirectional CATV system using a bidirectional CATV amplifying apparatus having a pilot signal generator that can prevent an increase in noise level when an unmodulated signal is input to an uplink. It is to provide.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the invention of claim 1 is a bidirectional CATV amplifying device provided with a status monitor unit.
The bidirectional CATV amplifying apparatus is provided with a pilot signal generator for outputting an upstream high-frequency signal on the upstream line of the CATV system, and the pilot signal of the upstream high-frequency signal output from the pilot signal generator is It is configured to be sent to the uplink via the status monitor unit.
[0006]
According to a second aspect of the present invention, the bidirectional CATV amplifying device comprises a node type optical transceiver having an optical transceiver on the input side of the amplifying device,
The bidirectional CATV amplifying apparatus is provided with a pilot signal generator for outputting an upstream high-frequency signal, and the pilot signal for the upstream high-frequency signal output from the pilot signal generator is passed through the status monitor unit. The optical signal is transmitted to the uplink of the bidirectional CATV amplifying apparatus, and further, an optical signal obtained by intensity-modulating the pilot signal is transmitted from the optical transmitter to the uplink of the CATV system.
[0007]
According to a third aspect of the present invention, the pilot signal generator operates by receiving power supply from the status monitor unit via a transmission line for transmitting a pilot signal transmitted from the pilot signal generator to the status monitor unit. Configured to do.
[0008]
According to a fourth aspect of the present invention, the pilot signal generator is configured to be detachable from the bidirectional CATV amplifier.
[0009]
According to a fifth aspect of the present invention, the pilot signal generator and the status monitor unit are integrally configured, and are configured to be detachable from the bidirectional CATV amplifier.
[0010]
According to a sixth aspect of the present invention, a bidirectional CATV system is configured using the bidirectional CATV amplifying device according to any one of the first to fifth aspects.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the bidirectional CATV amplifier shown in the present application. FIG. 2 is a block diagram showing a second embodiment of the bidirectional CATV amplifying apparatus shown in the present application. FIG. 3 is a block diagram showing an example in which a node type optical transceiver is configured by providing an optical transceiver in the bidirectional CATV amplifier according to the present invention. FIG. 4A is a schematic block diagram of the status monitor unit. (B) is a schematic block diagram of a status monitor unit incorporating a pilot signal generator. FIG. 5 is a schematic diagram showing an embodiment of a bidirectional CATV system using the bidirectional CATV amplifier of the present application shown in FIG.
[0012]
FIG. 1 shows a first embodiment of a bidirectional CATV amplifier according to the present application. In this bidirectional CATV amplifying apparatus 3, reference numeral 10 denotes a connection terminal on the center side (in other words, a center apparatus or a head end apparatus), and reference numeral 11 denotes a connection terminal on the terminal side. Reference numerals 14 and 15 denote filters for dividing or combining the transmission band signal into an upstream signal and a downstream signal, and are a first filter and a second filter, respectively. Reference numeral 12 denotes a downlink side amplifier that amplifies the downlink signal sent from the center side inputted to the connection terminal 10, and 13 amplifies the uplink signal sent from the terminal side inputted to the connection terminal 11. These amplifiers are configured to operate with automatic gain adjustment (hereinafter referred to as AGC) by a pilot signal.
[0013]
More specifically, a downlink signal (for example, a 70 to 770 MHz signal in the CATV system) transmitted from the center side input to the connection terminal 10 is a high-pass filter 14b (hereinafter referred to as HPF) and a low-pass filter 14a ( Hereinafter, it passes through the HPF 14 b of the first filter 14 consisting of “LPF” and is input to the amplifier 12 on the downlink side and amplified to a predetermined level by the amplifier 12. The amplified signal passes through the branch circuit 16 and then passes through the HPF 15b of the second filter 15 composed of the HPF 15b and the LPF 15a to send a downstream signal from the connection terminal 11 to the terminal side.
[0014]
Next, a signal input to the connection terminal 11 (for example, a signal of 10 to 55 MHz in the CATV system) passes through the LPF 15a of the second filter 15 including the LPF 15a and the HPF 15b, and then the upstream side amplifier 13 Is amplified to a predetermined level by the amplifier 13. The amplified signal passes through the multiplexing circuit 17 and then passes through the LPF 14a of the first filter 14 composed of the LPF 14a and the HPF 14b so as to send an upstream signal from the connection terminal 10 to the center side. .
[0015]
In the downlink, the branch circuit 16 is interposed between the amplifier 12 and the HPF of the second filter. A branch output terminal 16 a of the branch circuit 16 is connected to a status monitor via a transmission line 25. The signal is connected to the downlink input terminal 18a of the unit 18, and the signal output from the branch output terminal 16a is input to the status monitor unit via the transmission line 25.
Further, in the upstream line, the multiplexing circuit 17 is interposed between the amplifier 13 and the LPF of the second filter, and the multiplexing input terminal 17a of the multiplexing circuit 17 is a transmission line. The signal output from the status monitor unit 18 is input to the multiplexing input terminal 17a via the transmission line 26. The uplink output terminal 18b of the status monitor unit 18 is connected via the transmission line 26.
[0016]
The status monitor unit 18 receives a downlink signal from the center side that is branched and output from the branch output terminal 16a, reads a control signal sent from the center apparatus from the downlink signal, and uses the control signal as the control signal. Based on this, it has functions such as monitoring the operating state of each part of this amplifying device and monitoring the operating state of AGC and the like, and the data obtained by monitoring the operating state is used as a high-frequency signal as an uplink signal The uplink signal modulated as follows is sent from the combined output terminal 17a to the amplifier uplink via the transmission line 26.
That is, since the status monitor unit 18 and the downlink and uplink are connected via transmission lines 25 and 26 that pass high-frequency signals, among these transmission lines, 26 connected to the uplink is connected. It is intended to send a pilot signal to the uplink, and it is possible to send the pilot signal with a simple configuration.
[0017]
The configuration of the status monitor unit 18 of the present application will be described in more detail. The status monitor unit 18 of the present application includes a downlink input terminal 18a that receives a downlink signal from the center branched and output from the branch output terminal 16a via the transmission line 25, and a center signal from the downlink signal. The control signal sent from the device is read, and based on the control signal, the operation state of each part of the amplification device is monitored, the operation state of the AGC, etc. is monitored. A signal processing unit 19 for sending the data obtained by the monitor to the transmission line 26 as a high-frequency signal which is an uplink signal;
An uplink output terminal 18b for outputting an uplink signal including a data signal output from the signal processing unit 19 of the status monitor unit 18, and between the signal processing unit 19 and the uplink output terminal 18b. The coupling circuit 20 is provided and a multiplexing input terminal 18 c of the multiplexing circuit 20.
[0018]
The pilot signal generator 21 uses 10 MHz which is an uplink signal in the present application. The pilot signal generator 21 is disposed in the vicinity of the status monitor unit 18, and the pilot signal output from the pilot signal generator 21 is transmitted via a transmission line 27 to the multiplexing input terminal 18 c of the status monitor unit 18. (In other words, a pilot signal input terminal) is input to the status monitor unit 18. The pilot signal input from the pilot signal input terminal 18c is combined with the upstream signal by the multiplexing circuit 20, and is transmitted from the upstream signal output terminal to the upstream line. The pilot signal may be appropriately changed so that a signal within the band of the uplink signal may be used as described above, or a signal outside the band of the uplink signal, for example, 9 MHz may be used. Also good.
[0019]
The first and second filters are configured by combining HPF and LPF. However, the first and second filters are not limited to being configured by HPF and LPF, and may be configured by combining optimum filters as necessary. Needless to say.
Further, although the example in which the branch circuit 16 and the multiplexing circuit 17 are disposed on the output side of the amplifier is shown, the present invention is not limited to this embodiment and may be disposed in front of the amplifier. Needless to say, the arrangement locations may be appropriately combined.
Further, although the pilot signal generator 21 is built in the bidirectional CATV amplifier, it goes without saying that it may be built-in or detachable.
[0020]
Next, another embodiment of the present invention will be described with reference to FIG. In the following description, the same components as those of the bidirectional CATV amplification device in the first embodiment are given the same reference numerals, and detailed description thereof is omitted.
What will be described with reference to FIG. 2 is a bidirectional CATV amplifying apparatus having two bands for the uplink. In the embodiment, 10 to 55 MHz (hereinafter referred to as uplink L signal) and 650 to 770 MHz (hereinafter referred to as uplink H signal) are used as examples of uplink signals. It is configured.
[0021]
In this bidirectional CATV amplifying apparatus 3-1, reference numeral 14 denotes a first filter, which includes an LPF 14a having a cutoff frequency of 55 MHz and an HPF 14b having a cutoff frequency of 70 MHz. Reference numeral 30 denotes a third filter, which includes an LPF 30a having a cutoff frequency of 602 MHz and an HPF 30b having a cutoff frequency of 650 MHz. Reference numeral 31 denotes a fourth filter, which includes an LPF 31a having a cutoff frequency of 55 MHz and an HPF 31b having a cutoff frequency of 650 MHz.
[0022]
Reference numeral 32 denotes a fifth filter, which includes an LPF 32a having a cutoff frequency of 602 MHz and an HPF 32b having a cutoff frequency of 650 MHz. Reference numeral 33 denotes a sixth filter which includes an LPF 33a having a cutoff frequency of 55 MHz and an HPF 33b having a cutoff frequency of 650 MHz. Reference numeral 15 denotes a second filter, which includes an LPF 15a having a cutoff frequency of 55 MHz and an HPF 15b having a cutoff frequency of 70 MHz.
[0023]
A downlink signal from the center apparatus side is input to the downlink amplifier 12 via a downlink input path composed of the HPF 14b and the LPF 30a, and is amplified by a predetermined level. The amplified signal passes through the branch circuit 16, and then passes through the LPF 32a and HPF 15b to send a downlink signal from the connection terminal 11 to the terminal side. The downlink signal at this time has a band of 70 to 602 MHz.
[0024]
Next, the uplink signal from the terminal side is input to the uplink amplifier 13 via the uplink H signal input path including the HPF 15b, HPF 32b, and HPF 33b, and is amplified to a predetermined level. The amplified signal passes through the multiplexing circuit 17, and then passes through the HPF 31b, HPF 30b, and HPF 14b, and transmits an uplink H signal from the connection terminal 10 to the center side. The uplink H signal at this time has a band of 650 to 770 MHz.
Further, the uplink signal is input to the uplink amplifier 13 via the uplink L signal input path composed of the LPF 15a and the LPF 33a, and is amplified to a predetermined level. The amplified signal passes through the multiplexing circuit 17, and then passes through the LPF 31a and LPF 14a to send an uplink L signal from the connection terminal 10 to the center side. The uplink L signal at this time has a bandwidth of 10 to 55 MHz.
[0025]
In this embodiment, the uplink L signal is used to send a data signal monitoring the operating state of the bidirectional amplifying device to the center side, and the uplink signal H is an uplink signal because there is little interference radio wave. It is used for communication services such as the Internet connection service, taking advantage of the feature of low inflow noise.
Also in this embodiment, the installation state of the status monitor unit 18 and the pilot signal oscillator 26 and the method for transmitting the pilot signal are the same as those in the first embodiment, and thus detailed description thereof is omitted.
The first to sixth filters are composed of a combination of HPF and LPF. However, the first to sixth filters are not limited to being composed of HPF and LPF, and an optimum filter may be used as needed. Needless to say.
Further, although the example in which the branch circuit 16 and the multiplexing circuit 17 are disposed on the output side of the amplifier is shown, the present invention is not limited to this embodiment and may be disposed in front of the amplifier. Needless to say, the arrangement locations may be appropriately combined.
Further, in this bidirectional CATV amplifying apparatus, the pilot signal generator 21 is incorporated in the bidirectional CATV amplifying apparatus, but it goes without saying that it may be built-in or detachable.
[0026]
FIG. 3 illustrates a bidirectional CATV amplifying device configured as a node type optical transceiver by providing a bidirectional CATV amplifying device with an optical transceiver. In the following description, the same components as those in the bidirectional CATV amplifier of the above-described embodiment are given the same reference numerals, and detailed description thereof is omitted.
In FIG. 3, reference numeral 4 denotes a bidirectional CATV amplifier (that is, a node type optical transceiver) according to the present embodiment. 35 is an optical input terminal from the center side, 36 is an optical receiving unit, and an optical signal sent from the center apparatus side by an optical fiber cable is demodulated into an RF signal by the optical receiving unit 36. Later, the signal is input to the downlink signal amplifier 12. The downlink signal is amplified to a predetermined level in the downlink signal amplifier 12, passes through the branch circuit 16 and the HPF 15 b of the second filter 15, and is output from the terminal-side junction terminal 11.
[0027]
The uplink signal input from the terminal-side connection terminal 11 passes through the LPF 15a of the second filter and then is input to the uplink signal amplifier 13. The input signal is amplified to a predetermined level and then input to the optical transmission unit 37 via the multiplexing circuit 17. The input signal is modulated into an optical signal by the optical transmission unit 37 and transmitted from the optical output terminal 38 to the center apparatus side.
Also in this embodiment, the status monitor unit 18 and the pilot signal oscillator 26 are installed and the pilot signal transmission method is the same as that of the first embodiment, so that detailed description is omitted.
[0028]
In this embodiment, the bidirectional CATV amplifying device constituting the node type optical transceiver is limited to the embodiment in which the bandwidth of the uplink signal is 10 to 55 MHz and the downlink signal is 70 to 770 MHz as in the above-described embodiment. For example, the uplink signal has two uplink bands of an uplink L signal of 10 to 55 MHz and an uplink H signal of 650 to 770 MHz, and the downlink band is 70 to 602 MHz. For example, it may be changed as necessary. In the present invention, the second filter is configured by a combination of LPF and HPF, but is not limited to this embodiment, and may be configured by combining a filter such as a band pass filter.
In addition, although the example in which the multiplexing circuit 17 is disposed on the output side of the amplifier is shown, the present invention is not limited to this embodiment, and may be disposed in front of the amplifier.
Furthermore, in this embodiment, the pilot signal generator 21 is incorporated in the node type optical transceiver, but may be built-in or detachable.
[0029]
Although not shown in the first embodiment, the second embodiment, and the third embodiment of the present invention, the pilot signal generator 21 includes the pilot signal generator 18 and the status monitor unit 18. It is configured to operate by receiving power supply from the status monitor unit side via the transmission line 27 to be connected, and the pilot signal can be transmitted from the pilot signal generator 18 with a simpler configuration. The method of supplying power to the pilot signal generator 18 is not limited to the above embodiment, and may be changed as appropriate.
Further, in each of the above-described embodiments, as shown in FIG. 3B, the pilot signal generator 21 and the status monitor unit 18 may be integrally configured to form a pilot signal generator built-in status monitor unit 22. Also good. According to this configuration, it is not necessary to provide a transmission line for transmitting the pilot signal to the status monitor unit, and further, it is not necessary to superimpose a power source for operating the pilot signal generator on the transmission line from the status monitor unit side. Therefore, a bidirectional CATV amplifier with a built-in pilot signal generator can be realized with a simpler configuration.
[0030]
Next, a bidirectional CATV system using the node type optical transceiver 4 described in FIG. 3 will be described. In FIG. 5, 1 is a center device, and the center device 1 and the node type optical transceiver 4 are connected via an optical fiber cable 2. Reference numeral 5 denotes a coaxial cable, and a system is constructed by connecting a trunk distribution amplifier 6, a trunk branch amplifier 7, a distribution amplifier 8, and a tap-off 9 respectively.
[0031]
From the center device 1, not only a television signal but also a control signal is sent to a status monitor unit 18 built in the node type optical transceiver 4 over an optical fiber cable.
Further, from the node type optical transceiver 4, data obtained by monitoring the operational state of the amplification apparatus is received from the status monitor unit 18 incorporated in the bidirectional CATV amplification apparatus constituting the node type optical transceiver 4. The RF signal is multiplexed as an uplink signal, and the RF signal is modulated into an optical signal by the optical transmission unit 37 and transmitted.
Since the laser diode used in the node type optical transceiver used in the system configured in this way oscillates in a single longitudinal mode, the coherency is particularly high when there is no modulation. When a distance optical fiber cable is passed, intensity noise is generated in the fiber, and the noise characteristics deteriorate particularly in a frequency band of 50 MHz or less.
[0032]
In the HFC system as shown in this embodiment, the node is subdivided in order to cope with the high speed of the CATV network, but the influence of the upstream noise is reduced by this subdivision of the node. The C / N ratio is also improved. Therefore, it is necessary to operate the system with a stable C / N. However, when the uplink is in an unmodulated state, the above-described noise is generated from the node-type optical transceiver 4, so that the system C / N May be significantly degraded.
Therefore, the pilot signal for the uplink signal is transmitted to the node type optical transceiver 4 to prevent the generation of the noise. At this time, the pilot signal generator 21 is incorporated in the bidirectional CATV amplifier. Although a method has been considered, in order to multiplex a pilot signal from the pilot signal generator 21 to the uplink, a method of incorporating a pilot signal multiplexing circuit in the uplink is incorporated in each of the amplifiers having different characteristics. This necessitates time-consuming circuit design and increased costs.
[0033]
Therefore, as in the present embodiment, by using the status monitor unit 18 that can be incorporated into the node type optical transceiver 4, the status monitor unit 18 outputs the output signal of the status monitor unit 18 and the status monitor unit 18. System configuration using a node-type optical transceiver 4 that can transmit a pilot signal to the uplink on the same transmission line with a simple configuration of combining pilot signals output from a pilot signal generator 21 provided in the vicinity By doing so, it is possible to prevent noise from being generated by the optical transmitter on the uplink.
[0034]
In addition to the node type optical transmitter / receiver 4 shown in the present application, a bidirectional CATV amplifying apparatus configured so that an optical transmitter / receiver unit can be added later can be easily changed in accordance with the mounting state of the optical transmitter / receiver unit. Since the generator 21 is attached and the pilot signal output from the pilot signal generator 21 can be transmitted through the status monitor unit 18, the pilot signal can be transmitted without modifying the amplifier. It is possible to provide a bidirectional CATV amplifying apparatus that can supply a signal and does not worry about noise generation, and a system using the amplifying apparatus.
Needless to say, in the bidirectional CATV amplifying apparatus, the bidirectional CATV amplifying apparatus is attached to the transmission line of the bidirectional CATV system by the above-described configuration, and the amplifying apparatus is connected to the uplink of the transmission line. If a measuring instrument such as a spectrum analyzer is connected to the upstream side of the line by flowing a pilot signal, the amplifying device sending the signal and the upstream line test in the section where the measuring instrument is connected・ Adjustment is also possible.
[0035]
【The invention's effect】
As described above in detail, according to the first aspect of the present invention, in the bidirectional CATV amplifying apparatus provided with the status monitor unit, the bidirectional CATV amplifying apparatus includes a high-frequency signal in the upstream band on the uplink of the CATV system. Since the pilot signal generator for outputting the high-frequency signal in the upstream band output from the pilot signal generator is configured to be sent to the uplink via the status monitor unit, a simple operation is possible. With this configuration, it is possible to provide a bidirectional CATV amplifying apparatus capable of transmitting an upstream band frequency signal to the CATV system uplink and capable of testing and adjusting the CATV system uplink.
[0036]
According to the invention of claim 2, the bidirectional CATV amplifying apparatus comprises a node type optical transceiver having an optical transceiver on the input side of the amplifying apparatus, and the bidirectional CATV amplifying apparatus includes: , A pilot signal generator for outputting an upstream high-frequency signal is provided, and an upstream high-frequency pilot signal output from the pilot signal generator is connected to the upstream CATV amplifying device via the status monitor unit. Further, since the optical signal obtained by intensity-modulating the pilot signal is transmitted from the optical transmitter to the uplink of the CATV system, the optical signal is transmitted when the uplink is unmodulated. The noise generated by the transmitter can be held down with a simple configuration.
[0037]
According to the invention of claim 3, the pilot signal generator is supplied with power from the status monitor unit via a transmission line for transmitting the pilot signal transmitted from the pilot signal generator to the status monitor unit. Therefore, it is possible to output a signal that can be used for testing and adjusting the uplink of the CATV system. Further, it is possible to provide a bidirectional CATV amplifying apparatus having a built-in pilot signal generator capable of transmitting an upstream band frequency signal to the upstream line of the CATV system with a simple configuration.
[0038]
According to the invention of claim 4, since the pilot signal generator is configured to be detachable from the bidirectional CATV amplifying device, it can be appropriately attached as necessary as in the status monitor unit. Can be sent to the uplink via the status monitor unit, so that it is possible to provide a bidirectional CATV amplifier having high versatility and good mountability.
[0039]
According to the fifth aspect of the present invention, since the pilot signal generator and the status monitor unit are integrally configured and detachable from the bidirectional CATV amplifier, the pilot signal generator and the status monitor unit are provided. Since a transmission line for connection is not required, a bidirectional CATV amplifier excellent in ease of assembly and ease of handling can be provided.
[0040]
According to the invention of claim 6, since the bidirectional CATV system is configured using the bidirectional CATV amplifying device according to any one of claims 1 to 5, it is possible to construct a system that does not generate noise on the uplink. . In addition, in a system using a bidirectional CATV amplifier that can incorporate an optical transceiver, a pilot signal generator can be added easily and a pilot signal can be sent to the uplink even when an optical transceiver is installed later. Therefore, a system free from noise can be constructed from the optical transceiver. In addition, pilot signals necessary for the uplink of the system are transmitted, and the uplink can be adjusted and tested.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of a bidirectional CATV amplifier according to the present invention.
FIG. 2 is a block diagram showing a second embodiment of the bidirectional CATV amplifier according to the present invention.
FIG. 3 is a block diagram showing an example in which a node type optical transceiver is configured by providing an optical transceiver unit in the bidirectional CATV amplifier according to the present invention.
FIG. 4A is a schematic block diagram of a status monitor unit.
(B) is a schematic block diagram of a status monitor unit incorporating a pilot signal generator.
5 shows an embodiment of a bidirectional CATV system using the node type optical transceiver of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Center apparatus, 2 ... Optical fiber cable, 3, 3-1 ... Bidirectional CATV amplifier, 4 ... Node type optical transmitter / receiver, 5 ... Coaxial cable, 6 ... Trunk distribution amplifier, 7 ... Trunk branch amplifier, 8 ... Distribution Amplifier: 9 ... Tap-off, 10 ... Center device side connection terminal, 11 ... Terminal side connection terminal, 12 ... Downlink amplifier, 13 ... Uplink amplifier, 14 ... First filter, 15 ... Second filter 16 ... branch circuit, 16a ... branch output terminal, 17 ... multiplexing circuit, 17a ... multiplexing input terminal, 18 ... status monitor unit, 18a ... downlink input terminal, 18b ... uplink output terminal, 18c ... pilot Signal input terminal, 19 ... signal processor, 20 ... multiplexing circuit, 21 ... pilot signal generator, 22 ... pilot signal generator built-in status monitor unit, 5 ... Transmission line from downlink, 26 ... Transmission line to uplink, 27 ... Transmission line for pilot signal, 30 ... Third filter, 31 ... Fourth filter, 32 ... Fifth filter, 33 ... Sixth filter, 35 ... optical input terminal, 36 ... optical receiving unit, 37 ... optical transmitting unit, 38 ... optical output terminal,
14a, 15a, 30a, 31a, 32a, 33a ... LPF,
14b, 15b, 30b, 31b, 32b, 33b ... HPF

Claims (6)

In a bidirectional CATV amplifying apparatus provided with a status monitor unit,
The bidirectional CATV amplifying apparatus is provided with a pilot signal generator for outputting an upstream high-frequency signal on the upstream line of the CATV system, and the pilot signal of the upstream high-frequency signal output from the pilot signal generator is A bidirectional CATV amplifying apparatus, characterized in that the bidirectional CATV amplification apparatus is transmitted to an uplink via a status monitor unit. The bidirectional CATV amplifying device comprises a node type optical transceiver by providing an optical transceiver on the center device side of the amplifying device,
The bidirectional CATV amplifying apparatus is provided with a pilot signal generator for outputting an upstream high-frequency signal, and the pilot signal for the upstream high-frequency signal output from the pilot signal generator is passed through the status monitor unit. Both are configured to be transmitted to the uplink of the bidirectional CATV amplifying apparatus, and further to transmit an optical signal obtained by intensity-modulating the pilot signal from the optical transmitter to the uplink of the CATV system. CATV amplification device. The pilot signal generator is configured to operate by receiving power from the status monitor unit via a transmission line for transmitting a pilot signal transmitted from the pilot signal generator to the status monitor unit. The bidirectional CATV amplifying device according to claim 1, wherein the bidirectional CATV amplifying device is provided. 4. The bidirectional CATV amplifier according to claim 1, wherein the pilot signal generator is configured to be detachable from the bidirectional CATV amplifier. 4. The bidirectional CATV amplifying device according to claim 1, wherein the pilot signal generator and the status monitor unit are integrally formed and are detachable from the bidirectional CATV amplifying device. A bidirectional CATV system using the bidirectional CATV amplifying device according to any one of claims 1 to 5.

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