JP3498655B2 - Frequency agile apparatus, center communication control apparatus for CATV communication system, frequency agile control method, and CATV communication system - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a CATV (Com
munity antenna televisio
The present invention relates to a center communication control technique applicable to a communication system such as n), and more particularly to a frequency agile device that realizes prompt operation start after frequency change at low cost, a center communication control device of a CATV communication system, and a frequency agile control method.

[0002]

2. Description of the Related Art Conventionally, the frequency agile method has been
CATV (Community Antenna Te)
It is widely used for the center communication control device of the communication system in Levis), and it quickly searches for a low-noise frequency before the communication is interrupted mainly due to the upstream and downstream noise of the CATV transmission line which often interferes with the upstream communication. It is configured to maintain the communication state. The upstream and downstream noise of the CATV transmission line is generally unspecified and CAT
There are various operators depending on V, and it is difficult to eliminate the ingress noise.

By the way, since the CATV transmission line is connected to homes, high-speed communication using the CATV bidirectional transmission line has been attracting attention in recent years. Since it is generally necessary to improve communication quality in order to provide a communication service, there is a strong demand for somehow maintaining a communication state against upstream and downstream noise of a CATV transmission line. In order to meet this demand, for example, a conventional technique is conceivable in which an upstream receiving circuit for monitoring upstream and downstream noise of a CATV transmission line is provided exclusively for monitoring the noise condition in the upstream band in advance.

FIG. 5 is a circuit configuration diagram for explaining the conventional frequency agile device. In FIG. 5, 51
Is a downlink data multiplexing circuit, 52 is a downlink data transmission modulation circuit, 53 is a frequency control circuit, 54 is an operation tuner circuit,
55 is an upstream demodulation circuit, 56 is a noise monitoring tuner circuit,
57 is a noise level measurement circuit, 58 is a frequency change notification circuit, 500 is a downlink data signal, 502 is a downlink RF signal,
Reference numeral 601 indicates an upstream data signal, and reference numeral 600 indicates an upstream RF signal. Referring to FIG. 5, the conventional frequency agile device includes a downlink data signal 500 and a frequency change notification circuit 58.
Downlink data multiplexing circuit 51 that multiplexes the output signal of the downlink data transmission modulation circuit 5 that outputs the downlink RF signal 502 generated by modulating the output signal of the downlink data multiplexing circuit 51.
2 and a frequency control circuit 53 for keeping the modulation frequency constant.
And two upstream tuner circuits (one upstream tuner circuit is an operation tuner circuit 54, the other upstream tuner circuit is a noise monitoring tuner circuit 56 capable of knowing a noise state before changing the frequency), and an operation tuner. The upstream demodulation circuit 55 that generates and outputs the upstream data signal 601 based on the output signal from the circuit 54, and the noise level that measures the noise state in the output signal from the noise monitoring tuner circuit 56 and outputs it to the frequency control circuit 53. A measurement circuit 57 and a frequency change notification circuit 58 that receives the modulation frequency from the frequency control circuit 53, generates a signal indicating that the frequency has been changed, and outputs the signal to the downlink data multiplexing circuit 51 are provided.

[0005]

However, in the conventional frequency agile device, when a plurality of uplink communication paths are provided, the tuner circuit is required for the number of the uplink communication paths, so that the hardware of the receiving circuit is doubled. There was a problem that it was necessary.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a frequency agile device which realizes prompt operation start after frequency change at low cost, and center communication control of CATV communication system. An apparatus and a frequency agile control method are provided.

[0007]

The gist of the invention as set forth in claim 1 is to monitor the noise level in the upstream frequency band being operated in the upstream signal receiving section of the center communication device of the CATV communication system and to operate the noise level. When it is determined that the frequency agile device to change to a pre-specified frequency, means for investigating the noise state for a certain period of time after changing the frequency of the upstream signal receiving unit, and a plurality of destination frequencies to be agile A frequency agile device characterized by having a means for investigating the noise state and sequentially scanning the frequencies when it cannot be operated, and for returning to the original frequency after a certain period of operation at the agile destination frequency or after the end of scanning. Exist in. Further, the gist of the invention according to claim 2 is that, when changing the frequency, after stopping upstream transmission of the communication device in advance, and notifying the communication device of a frequency agile state, after determining that it is operable. The frequency agile device according to claim 1, further comprising means for notifying an upstream frequency change of the communication device and restarting the operation. Further, claim 3
In the center communication control device of a CATV communication system having a downlink data multiplexing circuit, a downlink data transmission modulation circuit, an uplink tuner circuit, an uplink data demodulation circuit, and an uplink noise level measuring circuit, A frequency agile determination circuit that determines a threshold value while monitoring, a frequency selection circuit that selects a destination frequency according to the determination result and sets the frequency to the upstream tuner circuit,
A CATV having a terminal control message generation circuit for controlling uplink transmission stop, uplink frequency change notification, and / or uplink transmission restart to a communication device of a terminal.
It exists in the center communication control device of the communication system. Further, the gist of the invention according to claim 4 is that the frequency agile determination circuit increases the noise monitoring interval so as not to hinder the communication service in operation, and investigates the noise level after the frequency change. In this case, a timer for reducing the noise monitoring interval, a means for reading the noise level measurement value at the timing of the timer, and a threshold for comparing the noise level measurement value with a threshold value to determine whether the noise state is large or small. 4. The C according to claim 3, further comprising a value judging circuit.
It exists in the center communication control device of the ATV communication system. Further, the gist of the invention according to claim 5 is that the frequency selection circuit sequentially stores a frequency table in which the changed frequency is stored and, when it is determined that the frequency selection circuit cannot be operated when investigating the noise state,
5. A pointer control circuit for controlling an address of the frequency table to perform a frequency scan, and a timer for generating a timing for returning to the original frequency after a certain time of operation at the agile destination frequency. The center communication control device of the CATV communication system described in 1. The gist of the invention according to claim 6 is CA
This is a frequency agile control method for monitoring the noise level in the operating upstream frequency band in the upstream signal receiving unit of the center communication device of the TV communication system, and changing to a pre-specified frequency when it is determined that the noise level cannot be operated. The step of investigating the noise state for a certain period of time after changing the frequency of the upstream signal receiving section, preparing a plurality of change destination frequencies to be agile, sequentially scanning the frequencies when the noise state cannot be investigated and operated, A frequency agile control method is characterized by having a step of returning to the original frequency after a certain time of operation at the agile destination frequency or after the end of scanning. In addition, the gist of the invention according to claim 7 is to: before changing the frequency, stop upstream transmission of the communication device and notify the communication device of the frequency agile state, and after determining that it is operable. 7. The frequency agile control method according to claim 6, further comprising the step of notifying an upstream frequency change of the communication device and restarting the operation. In addition, the gist of the invention described in claim 8 is a frequency agile control method for executing a downlink data multiplexing step, a downlink data transmission modulation step, an uplink tuner step, an uplink data demodulation step, and an uplink noise level measuring step. A frequency agile determination step of determining a threshold value while monitoring the level, a frequency selection step of selecting a destination frequency according to the determination result and setting the frequency to the upstream tuner step, and upstream transmission stop to a communication device of a terminal, There is a frequency agile control method including a terminal control message generation step of controlling an uplink frequency change notification and / or an uplink transmission restart. Further, the gist of the invention according to claim 9 is that in the frequency agile determination step, the noise monitoring interval is increased so as not to hinder the communication service in operation, and the noise level after the frequency change is investigated. In this case, a timer step of reducing the interval of noise monitoring, a step of reading a noise level measurement value at the timing of the timer step, and a comparison between the noise level measurement value and a threshold value to determine whether the noise state is large or small. The frequency agile control method according to claim 8, further comprising a threshold value determination step. Further, the gist of the invention described in claim 10 is that, in the frequency selecting step, when it is determined that the frequency table storing the changed frequency and the noise state cannot be operated, the addresses of the frequency table are sequentially set. The frequency agile according to claim 8 or 9, further comprising: a pointer control step of controlling and frequency scanning, and a timer step of generating a timing of returning to an original frequency after a certain time of operation at an agile destination frequency. It depends on the control method. Further, the gist of the invention described in claim 11 is a CATV communication system including the center communication control device according to any one of claims 3 to 5, wherein a router is provided in a higher-order network forming a backbone. C for the center communication control device connected to each other and the communication device at the subscriber's house connected in parallel to a plurality of optical nodes on the downstream side.
A CATV communication system is characterized in that it has a headend device that controls distribution of ATV communication data.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A first feature of the following embodiment is to monitor a noise level in an operating upstream frequency band in an upstream signal receiving section of a CATV center communication control device in a CATV communication system, When it is determined that the noise level cannot be operated, it is a frequency agile method of changing to a frequency designated in advance, means for stopping the uplink transmission of the communication device before the frequency change, and notifying the communication device of the frequency agile state, There is provided a means for investigating the noise state for a certain period of time after changing the frequency of the upstream receiving section, notifying the operation device of the upstream frequency change after determining that the operation is possible, and restarting the operation. The second feature is that multiple agile destination frequencies are prepared, the frequencies are sequentially scanned when the noise state is investigated and the operation is not possible, and the original frequency is used after the scanning is completed or after the agile destination frequency is operated for a certain period of time. The means to return to is provided.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a functional block diagram for explaining the frequency agile device according to the embodiment of FIG. In FIG. 1, 1 is a frequency agile controller, 2 is a downlink data multiplexing circuit, 3 is a downlink data transmission modulation circuit, 4 is an uplink tuner circuit, 5 is an uplink data demodulation circuit, 6 is an uplink noise level measuring circuit, and 11 is a terminal. Control message generation circuit, 12 frequency agile determination circuit, 13 frequency selection circuit, 100 downlink data signal, 101 downlink multiplexed data, 102 downlink RF signal, 200 uplink RF signal, 201 from uplink tuner circuit 4. An output signal, 202 is an upstream data signal, a is a read signal, b is a noise level measurement value, c is a determination signal, d is a control signal, e is a frequency value, f is a tuner selection signal, and g is a return signal. There is.

Referring to FIG. 1, the frequency agile apparatus according to the present embodiment has a frequency agile control unit 1, a downlink data multiplexing circuit 2, a downlink data transmission modulation circuit 3, an upstream tuner circuit 4, and an upstream data demodulation. A circuit 5 and an upstream noise level measuring circuit 6 are provided.

The frequency agile control unit 1 reads the noise level data from the upstream noise level measuring circuit 6 periodically to judge whether the noise level is operable or not, and the frequency agile judgment circuit 12 to store the changed frequency. A frequency selection circuit 13 that sequentially changes the uplink reception frequency according to the table 31 and a terminal control message generation circuit 11 that notifies the terminal communication device of the uplink transmission stop and restart and the uplink frequency change are provided.

The upstream noise level measuring circuit 6 determines whether or not an upstream burst signal from the communication device is present, measures the noise level in the frequency band by utilizing the interval between the burst signals, and the frequency agile determining circuit 12 Can obtain noise level data measured at regular intervals and monitor the noise level even under normal operating conditions. In addition, by controlling the stop and restart of the uplink transmission of the communication device, the operation of investigating the noise state of the changed frequency and searching for an operable frequency in the absence of the uplink transmission data is executed. Therefore, it is not necessary to have a separate receiving circuit for noise measurement, and the operation can be restarted after confirming the noise condition, so unnecessary hardware is unnecessary.

Next, a description will be given of a first embodiment in which the frequency agile device of this embodiment is applied to a transmitting / receiving section of a center communication control device. Referring to FIG. 1, the transmission / reception unit of the center communication control device according to the present embodiment includes a transmission unit and an upstream signal reception unit, and the transmission unit includes a downstream data multiplexing circuit 2 and a downstream data transmission modulation circuit 3, and receives an upstream signal reception. The unit includes an upstream tuner circuit 4, an upstream data demodulation circuit 5, and an upstream noise level measuring circuit 6. Frequency agile controller 1
Has a terminal control message generation circuit 11, a frequency agile determination circuit 12, and a frequency selection circuit 13. The downlink data signal 100 is supplied to the downlink data multiplexing circuit 2,
The signal is multiplexed with the control signal d from the terminal control message generation circuit 11. The downlink multiplexed data 101 which is the output of the downlink data multiplexing circuit 2 is processed by the downlink data transmission modulation circuit 3 and output as a downlink RF signal 102. On the other hand, the upstream RF signal 200 is frequency-tuned by the upstream tuner circuit 4, the output signal 201 from the upstream tuner circuit 4 is demodulated by the upstream data demodulation circuit 5, and the upstream data signal 202.
Is output as. Further, the output signal 201 from the upstream tuner circuit 4 is supplied to the upstream noise level measuring circuit 6,
It is used to measure the level of the noise component when the upstream data signal 202 does not exist.

For the processed data, the frequency agile controller 1 of this embodiment uses the upstream noise level measuring circuit 6
While periodically supplying the read signal a to, the noise level measurement value b fetched from the upstream noise level measurement circuit 6 according to the read signal a is compared with the threshold value,
When it is larger than the threshold value, the determination signal c indicating that it is determined to be large is generated and output. Further, the terminal control message generation circuit 11 processes the judgment signal c, generates an uplink transmission stop message for the corresponding communication device, and outputs the message to the downlink data multiplexing circuit 2. Further, the decision signal c from the frequency agile decision circuit 12 is sent to the frequency selection circuit 13
At the same time, the tuner tuning signal f generated by selecting the change destination frequency is output to the up tuner circuit 4 to change the up frequency setting. Furthermore, the noise level measurement value b is taken in even after the frequency setting is changed, and if it is smaller than the threshold value, it is determined to be small. Judgment signal c at this time
Is processed by the terminal control message generation circuit 11, an uplink frequency change notification and an uplink transmission start message are generated for the corresponding communication device and output to the downlink data multiplexing circuit 2 to perform operation start processing. The frequency selection circuit 13 performs a timer process on the operating time at the changed frequency to restore the original operating frequency.

FIG. 2 shows the frequency agile decision circuit 1 of FIG.
It is a functional block diagram for explaining 2. In FIG. 2, 20 is a noise level value monitoring control circuit, 21 is a timer A, 22 is a timer B, 23 is a timer C, and 24 is a threshold value judging circuit. Referring to FIG. 2, the frequency agile determination circuit 12 of the present embodiment includes a noise level value monitoring control circuit 20, a timer A21, a timer B22, and
A timer C23 and a threshold value judgment circuit 24 are provided.

The noise level value monitoring control circuit 20 first outputs the read signal a according to the timing generation of the timer A21 and supplies it to the upstream noise level measuring circuit 6. The read noise level measurement value b is supplied to the threshold value judgment circuit 24. The threshold value judgment circuit 24 judges whether it is larger or smaller than the threshold value by comparing with a threshold value provided in advance, and outputs a judgment signal c.

The noise level value monitoring control circuit 20 switches the timer A21 to the timer B22 based on the supplied judgment signal c when the judgment result is excessive and reads the noise level measurement value b at the frequency to be changed. Generate timing. Further, the return signal g to the original operating frequency is supplied from the frequency selection circuit 13, and the reading of the noise level measurement value b is started according to the timing of the timer C23.
Thus, the processing described above is executed.

FIG. 3 is a functional block diagram for explaining the frequency selection circuit 13 of FIG. In FIG. 3, 30 is a pointer control circuit, 31 is a frequency table, 32 is a frequency setting circuit, and 33 is a timer D. Referring to FIG. 3, the frequency selection circuit 13 of the present embodiment includes a pointer control circuit 30, a frequency table 31, a frequency setting circuit 32, and a timer D33.

The pointer control circuit 30 of this embodiment has the first address value of the frequency table 31. The frequency table 31 has frequency values e that can be changed in advance.
Is set. Based on the judgment signal c supplied from the threshold judgment circuit 24, the pointer control circuit 30 operates [current address value] +1 to move the address value to the frequency table 31 when the judgment signal c indicates a large value. Supply. In response to this, the frequency table 31 outputs the frequency value e corresponding to the address value to the terminal control message generation circuit 11 and the frequency setting circuit 32. Frequency setting circuit 32
Converts the supplied frequency value e into a tuner channel selection signal f and outputs it to the upstream tuner circuit 4. The terminal control message generation circuit 11 uses the supplied frequency value e to generate an uplink frequency change notification to the communication device.

The downlink data multiplexing circuit 2 shown in FIG.
The downstream data transmission modulation circuit 3, the upstream tuner circuit 4, the upstream data demodulation circuit 5, and the upstream noise level measurement circuit 6 are well known to those skilled in the art and are not directly related to the present invention, and therefore their detailed configurations will be described. Omit it.

Next, the operation of the frequency agile device (frequency agile control method) will be described. FIG. 4 is a flowchart for explaining the frequency agile control method according to the first embodiment of the present invention. Referring to FIG. 4, in the present embodiment, the noise level monitoring operation is first performed in the normal operation state, so the noise level measurement control circuit 20 reads the noise level measurement value b and the threshold value judgment circuit 24
Then, the noise level measurement value b is compared with the threshold value (step Z1 → step Z2). If the result of threshold determination is small (“small” in step Z2), the noise level measurement value b is repeatedly read at the timing of the timer A21 (“small” in step Z2 → step Z2A → step Z).
1 → step Z2 → ...).

On the other hand, if the threshold value judgment result is large ("large" in step Z2), the frequency agile operation is executed. That is, the terminal control message generation circuit 11 issues a terminal upstream transmission stop notification (step Z3), and the pointer control circuit 30 sets the pointer value of the frequency table 31 to [current address value] +1 (step Z4). It is determined whether or not the pointer value of the frequency table 31 has reached the maximum address value (step Z5). If the pointer value of the frequency table 31 is not the maximum address value (“NO” in step Z5), the frequency table 31
The frequency to be changed is selected from (step Z6) and the frequency is set (step Z7).

After setting the frequency (step Z7), the noise level measurement value b is read at the changed frequency (step Z).
8) Threshold value judgment (step Z9) is executed. Here, when the threshold value judgment result is large (“large” in step Z9), the next frequency in the frequency table 31 is selected and repeatedly examined. If the threshold judgment result is (step Z
9) "Small") and the survey is completed (step Z1)
0: YES) is a terminal uplink frequency change notification (step Z
11) Issue a terminal uplink transmission restart notification (step Z1)
2) Then start operation.

After the operation is started, the noise level is monitored after waiting for a time with the timer C23 (step Z13). When the pointer value of the frequency table 31 reaches the maximum address value (YES in step Z5), when the operation is started at the frequency-agile changed destination frequency (step Z1).
2) or when a certain time has passed by the timer D33 (step Z14), after the terminal uplink transmission stop notification (step Z15), the address is set to an initial value (step Z16) to select the original frequency before frequency agile. (Step Z17), and then step Z7 → Z8 →
The process of Z9 is executed, and the noise level investigation (step Z1
When the result of 0) is small (“small” in step Z10)
As described above, the operation is restarted at the original frequency (steps Z11 → Z12 → Z13 → ...).

As described above, according to this embodiment, the following effects can be obtained. The first effect is that the frequency search of the frequency agile operation can be executed in a short time. The reason is that when performing frequency agile operation, terminal uplink transmission is stopped, while changing the frequency, a noise level survey is performed at the changed frequency,
This is because the operable frequencies are searched in order, so that the uplink signal from the terminal does not rise during the search.

A second effect is that the communication operation can be immediately set after the operation is restarted. The reason is that, in the present embodiment, frequency agile operation is performed after the terminal uplink transmission is stopped, and the terminal frequency is changed to an operable frequency and the terminal transmission is restarted, so that no terminal authentication failure occurs in the noise investigation.

The third effect is that it is not necessary to prepare another hardware for noise investigation, and the hardware scale can be reduced. The reason is that in this embodiment, the noise level investigation is executed at the changed frequency.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 6 shows a center communication control device 614 equipped with the frequency agile device 1 of the present invention.
FIG. 3 is a network configuration diagram for explaining an implementation form of the above in a CATV communication system 61 (CATV station). Figure 6
, 61 is a CATV communication system, 62 is a backbone, 611 is an antenna, 612 is a TV (television) receiving device, 613 is a head end device (HE), 614 is a center communication control device, 615 is a server, 616 is a router, 617. Is a parabolic antenna, 621 is an Internet service provider (ISP), 622 is an upper network, 71 is an optical RF transmission line, 72 is an optical node, 7
3 is a subscriber's house, 731 is a communication device, 732 is a communication terminal,
741 is a TV tuner, 742 is a television receiver, 74
Reference numeral 3 indicates a CATV tuner.

Referring to FIG. 6, a CATV communication system 61 (CATV station) is a center communication control device 6 of the present invention.
Equipped with 14. The center communication control device 614 is connected to the upper network 622 that constitutes the backbone 62 via the router 616 and the Internet service provider 621 (ISP), and also the server 6
15 is connected via a network.

Headend device 6 connected to center communication control device 614 and TV (television) receiving device 612
A plurality of 13 (HE) are connected in parallel to a plurality of optical nodes 72, ..., 72 via an optical RF transmission line 71. TV
To the (television) receiver 612, a parabolic antenna 617 for transmitting and receiving satellite broadcast waves and an antenna 611 for transmitting and receiving terrestrial broadcast waves are connected.

An optical node 72 is connected to the optical RF transmission line 71, and a CAT is provided downstream of the optical node 72.
A plurality of subscriber homes 73, which are distribution destinations of V communication data, are connected in parallel on a coaxial transmission line.

A communication device 731 connected to the coaxial transmission line and a communication terminal 732 connected to the downstream side of the communication device 731 are connected to the subscriber home 73. As the communication terminal 732 for transmitting / receiving CATV communication data, for example, a PC (personal computer) or a TEL (Internet phone) can be connected.

Another typical configuration of the subscriber's home 73 is, for example, a TV tuner 741 and a television receiver 74.
An AV system in which the two are combined, an AV system in which the CATV tuner 743 and the television receiver 742 are combined, and the like can be considered.

In the above-described embodiment, the threshold value judgment circuit 24 is not limited to the threshold value judgment, and a circuit for counting the large number of judgment results and judging the number of times based on the count value is added. Conditions may be added. Further, the frequency agile control unit 1 does not have a circuit configuration by hardware, but an S / W by a CPU (central processing unit).
It can also be realized by means of (software). Further, it is obvious that the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified within the scope of the technical idea of the present invention. Further, the number, positions, shapes, etc. of the above-mentioned constituent members are not limited to those in the above-mentioned embodiment, and the number, positions, shapes, etc. suitable for carrying out the present invention can be adopted. Moreover, in each figure, the same components are denoted by the same reference numerals.

[0035]

Since the present invention is configured as described above, it has the following effects. The first effect is that the frequency search of the frequency agile operation can be executed in a short time. The reason is that when performing frequency agile operation, terminal uplink transmission is stopped, while changing the frequency, the noise level is investigated at the changed frequency and the operable frequencies are searched in order. This is because the upstream signal from the terminal does not come up.
The second effect is that the communication operation can be performed immediately after the operation is restarted. The reason is that in the present invention, the frequency agile operation is performed after the terminal uplink transmission is stopped, the terminal frequency is changed to an operable frequency, and the terminal transmission is restarted. Therefore, the authentication of the terminal does not occur in the noise investigation. The third effect is that it is not necessary to prepare another hardware for noise investigation, and the hardware scale can be reduced. The reason is that the present invention performs a noise level investigation at the destination frequency.

[Brief description of drawings]

FIG. 1 is a functional block diagram for explaining a frequency agile device according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram for explaining the frequency agile determination circuit of FIG.

FIG. 3 is a functional block diagram for explaining the frequency selection circuit of FIG.

FIG. 4 is a flowchart for explaining a frequency agile control method according to the first embodiment of the present invention.

FIG. 5 is a circuit configuration diagram for explaining a conventional frequency agile device.

FIG. 6 is a network configuration diagram for explaining an implementation mode of a center communication control device equipped with the frequency agile device of the present invention in a CATV communication system.

[Explanation of symbols]

1 ... Frequency agile controller 2 ... Downlink data multiplexing circuit 3. Downlink data transmission modulation circuit 4 ... Upward tuner circuit 5 ... Upstream data demodulation circuit 6 ... Upstream noise level measurement circuit 11 ... Terminal control message generation circuit 12 ... Frequency agile judgment circuit 13 ... Frequency selection circuit 20 ... Noise level value monitoring control circuit 21 ... Timer A 22 ... Timer B 23 ... Timer C 24 ... Threshold value judging circuit 30 ... Pointer control circuit 31 ... Frequency table 32 ... Frequency setting circuit 33 ... Timer D 61 ... CATV communication system 62 ... Backbone 71 ... Optical RF transmission path 72 ... Optical node 73 ... Subscriber's house 100 ... Downlink data signal 101 ... Downlink multiplexed data 102 ... Downlink RF signal 200 ... Upstream RF signal 201 ... Output signal from upstream tuner circuit 202 ... upstream data signal 611 ... Antenna 612 ... TV (television) receiver 613 ... Headend device 614 ... Center communication control device 615 ... server 616 ... Router 617 ... Parabolic antenna 621 ... Internet service provider 622 ... Upper network 731 ... Communication device 732 ... Communication terminal 741 ... TV tuner 742 ... Television receiver 743 ... CATV tuner a ... Read signal b ... Measured noise level c ... Judgment signal d ... control signal e ... Frequency value f ... Tuner tuning signal g ... Return signal

Claims (11)

(57) [Claims] 1. When a noise level in an operating upstream frequency band is monitored in an upstream signal receiving unit of a center communication control device of a CATV communication system and it is determined that the noise level cannot be operated, a frequency designated in advance is changed. A frequency agile device, a means for investigating a noise state for a certain period of time after changing the frequency of the upstream signal receiving section, and a plurality of destination frequencies to be agile prepared, and a frequency when the noise state cannot be investigated and operated. Sequentially scan,
A frequency agile device having means for returning to the original frequency after a certain time of operation at the agile destination frequency or after the end of scanning. 2. When changing the frequency, means for stopping upstream transmission of the communication device in advance and notifying the communication device of a frequency agile state, and notifying of change of the upstream frequency of the communication device after determining that the communication device is operable. The frequency agile device according to claim 1, further comprising means for restarting operation. 3. A center communication control device of a CATV communication system having a downlink data multiplexing circuit, a downlink data transmission modulation circuit, an uplink tuner circuit, an uplink data demodulation circuit and an uplink noise level measuring circuit, while monitoring the uplink noise level. A frequency agile judgment circuit for judging a threshold value, a frequency selection circuit for selecting a change destination frequency according to a judgment result and setting a frequency to the uplink tuner circuit, an uplink transmission stop, an uplink frequency change notification to a communication device of a terminal, And / or a CATV having a terminal control message generation circuit for controlling resumption of uplink transmission
A center communication control device for a communication system. 4. The frequency agile determination circuit increases the noise monitoring interval so as not to hinder the communication service in operation, and decreases the noise monitoring interval when investigating the noise level after the frequency change. A timer for reading, a means for reading a noise level measurement value at the timing of the timer, and a threshold value determination circuit for comparing the noise level measurement value with a threshold value to determine whether the noise state is large or small. The center communication control device of the CATV communication system according to claim 3. 5. The frequency selection circuit, a frequency table storing the changed frequency, and a pointer control for sequentially controlling the address of the frequency table and scanning the frequency when it is determined that the frequency table cannot be operated when investigating the noise state. 5. The center communication control device for a CATV communication system according to claim 3, further comprising a circuit and a timer for generating a timing for returning to the original frequency after operating for a certain time at the agile destination frequency. 6. A frequency to be changed to a frequency designated in advance when a noise level in an operating upstream frequency band is monitored by an upstream signal receiving unit of a center communication device of a CATV communication system and it is determined that the noise level cannot be operated. An agile control method, the step of investigating the noise state for a certain period of time after changing the frequency of the upstream signal receiving section, preparing a plurality of change destination frequencies to be agile, and investigating the noise state Sequentially scan,
A frequency agile control method comprising a step of returning to the original frequency after a certain time of operation at the agile destination frequency or after completion of scanning. 7. When changing the frequency, a step of stopping upstream transmission of the communication device in advance and notifying the communication device of a frequency agile state, and notifying of the upstream frequency change of the communication device after determining that the communication device is operable 7. The frequency agile control method according to claim 6, further comprising the step of restarting the operation. 8. A frequency agile control method for performing a downlink data multiplexing step, a downlink data transmission modulation step, an uplink tuner step, an uplink data demodulation step, and an uplink noise level measuring step, wherein a threshold value is monitored while monitoring the uplink noise level. A frequency agile determination step of determining, a frequency selecting step of selecting a destination frequency according to the determination result and setting the frequency to the upstream tuner step, stopping upstream transmission, notifying upstream frequency change to the communication device of the terminal, and / or A frequency agile control method comprising a terminal control message generation step of controlling resumption of uplink transmission. 9. The frequency agile determination step increases the noise monitoring interval so as not to hinder the communication service in operation, and decreases the noise monitoring interval when investigating the noise level after the frequency change. And a step of reading a noise level measurement value at the timing of the timer step, and a threshold value determining step of comparing the noise level measurement value with a threshold value to determine whether the noise state is large or small. The frequency agile control method according to claim 8. 10. The frequency selection step comprises: a frequency table storing a changed frequency; and pointer control for sequentially controlling the address of the frequency table and performing a frequency scan when it is determined that the frequency table cannot be operated when investigating a noise condition. 10. The frequency agile control method according to claim 8, further comprising a step and a timer step of generating a timing of returning to the original frequency after operating for a certain time at the agile destination frequency. 11. A CATV communication system comprising the center communication control device according to claim 3, wherein the center communication control is connected to a higher-order network forming a backbone via a router. A CATV communication system comprising: a device; and a headend device that controls distribution of CATV communication data to a communication device at a subscriber's home, which is connected in parallel to a plurality of optical nodes on the downstream side.