JPH0583709A - Monitor for two-way catv - Google Patents

Abstract

PURPOSE:To monitor an image and sound corresponding to all reception channels in real time from an optional position of a transmission line. CONSTITUTION:A control transmitter 20 of a monitor terminal equipment 13 sends a channel control signal having a call signal corresponding to a monitored channel to a cable transmission system 12 as a 1st incoming signal f1, and the signal is converted into a 1st outgoing signal f1' by a center 10 and a tunable television demodulator 29 tunes and selects the monitored channel based on the channel control signal received by a control receiver 25 of a terminal equipment 11 and demodulates the channel selection signal into a video signal and an audio signal, and an incoming channel television modulator 30 modulates the signals again into a television signal and sends the signal to the said cable transmission system 12 as a 2nd incoming signal f2, and the center 10 converts the signal into a 2nd outgoing signal f2' and sends it through loopback, and a television demodulator 23 of a monitor terminal equipment 13 demodulates the signal into a video signal and a sound signal and a monitor television receiver 24 monitors the output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional CATV monitoring device for bidirectionally transmitting a television signal between a center side and a terminal side via a cable transmission system.

[0002]

2. Description of the Related Art Generally, a network of a CATV system gradually spreads toward terminals while being branched and distributed from a CATV transmission center toward a large number of terminals.
It has a so-called dendritic structure. In operating such a CATV system, the following five methods are conceivable as methods for monitoring the transmission image from the center side to the terminal side. (1) A method of branching and directly monitoring the sending signal to the cable transmission system at the CATV sending center. (2) A method in which a dedicated monitor is installed for a specific terminal and you can go to that location and monitor.

(3) The amplification operation state of a line amplifier used in a CATV system, for example, a cable transmission system,
A method of constantly monitoring on the center side with a status monitoring system. (4) A method in which the CATV network is configured in a loop and the terminal is returned to the CATV transmission center for monitoring and monitoring. (5) A method in which the image transmitted from a specific terminal is returned to the center side via a dedicated line and monitored. However, the monitoring method described in (1) above cannot monitor the monitor image at the target terminal. Also, with the monitoring method described in (2) above, it is not possible to monitor the monitor image in the terminal in real time.

Further, in the monitoring method described in (3) above,
Since the transmission level of the pilot signal in the line amplifier is monitored, the video signal itself cannot be monitored.

Then, in the monitoring method described in (4) above,
By pulling back the tip of the CATV transmission path, the monitoring point is specified, and the monitor image at the target terminal cannot be monitored.

Further, in the monitoring method described in (5) above, it is economically disadvantageous to lay a dedicated line, and the monitoring point is completely fixed, so that the degree of freedom is completely eliminated.

[0007]

That is, the above-mentioned CAT
In the conventional transmission image monitoring method in the V system, all received images at the target terminal to be monitored are
There is a drawback that it is not possible to monitor in real time from any position on the transmission line without using the dedicated line.

The present invention has been made in view of the above problems.
There is no need to install a dedicated monitoring line for the target terminal,
Video and audio corresponding to all receiving channels are CAT
It is an object of the present invention to provide a bidirectional CATV monitoring device that enables real-time monitoring from any position on a V transmission line.

[0009]

That is, a bidirectional CATV monitoring device according to the present invention is a bidirectional CATV transmission for bidirectionally transmitting a television signal between a center side and a terminal side via a cable transmission system. In the system, a monitoring terminal that is branched and connected to an arbitrary position of the cable transmission system to monitor the terminal reception state, and a channel control signal that is provided in the monitoring terminal and that corresponds to the designation of the monitored channel is generated to generate the first uplink. A control oscillator for sending out to the cable transmission system as a signal f1 and a channel control signal as the first upstream signal f1 from the above-mentioned control oscillator provided on the center side are converted into a first downstream signal f1 '. A first frequency converter for sending to the cable transmission system, and a channel control signal provided on the terminal side as a first downlink signal f1 'from the first frequency converter. A receiving control receiver, and a tunable television demodulator that tunes the receiving channel on the terminal side to the specified channel based on the channel control signal received by the controlling receiver and demodulates the television signal into video and audio signals. , An up-channel television modulator for modulating the demodulated signal from the tunable television demodulator into a television signal and sending it to the cable transmission system as a second up-stream signal f2, and the up-channel television modulation provided on the center side. A second frequency converter for converting a television signal, which is the second upstream signal f2 from the receiver, into a second downstream signal f2 'and sending it to the cable transmission system, and the second frequency converter provided in the monitoring terminal. Second downlink signal f2 'from
The television demodulator that demodulates the television signal into a video and audio signal, and a monitoring monitor television that outputs video and audio according to the demodulated signal from the television demodulator.

[0010]

In other words, the channel from the monitoring terminal provided at an arbitrary position of the cable transmission system is equipped with the control receiver, the tunable TV demodulator, and the up channel TV modulator for the target terminal. The control signal is returned from the center side and given to the above terminal, and the TV signal of the designated channel selected based on this channel control signal is returned to the center side again and given to the monitoring terminal, demodulated as video and audio signals and monitored. By doing so, it becomes possible to monitor the video and audio corresponding to an arbitrary reception channel in real time from an arbitrary position of the cable transmission system by using the cable transmission system of the existing system.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a bidirectional CATV monitoring device. The CATV transmission center 10 and the terminal 11 are:
It is connected via a cable transmission system 12 using a coaxial cable or the like, and a monitoring terminal 13 for monitoring the terminal reception state is branched and connected to an arbitrary position of the cable transmission system 12. The CATV transmission center 10 has a first
And second frequency converters 14 and 15 are provided.

The first frequency converter 14 converts the channel control signal, which is given as the first upstream signal of the frequency f1 from the monitoring terminal 13 via the cable transmission system 12, the demultiplexer 16 and the distributor 17, into the frequency. The frequency is converted to f1 ', and the frequency f is converted by the first frequency converter 14.
The channel control signal converted into 1'is used as the first downlink signal to the terminal 11 by the mixers 18 and 19 and the demultiplexer 1 described above.
It is sent to the cable transmission system 12 via 6.

The second frequency converter 15 includes the terminal 11 described above.
The received television signal corresponding to the monitored channel given as the second upstream signal of frequency f2 from the cable transmission system 12, the demultiplexer 16 and the distributor 17 from the frequency f2
The frequency of the received television signal converted into the frequency f2 'by the second frequency converter 15 is used as the second downlink signal to the monitoring terminal 13 and mixed in the mixer 1'.
It is sent out to the cable transmission system 12 via 8, 19 and the demultiplexer 16. On the other hand, the monitoring terminal 13 is provided with a control transmitter 20.

The control oscillator 20 generates a channel control signal having a transmission signal corresponding to a monitored television channel designated by a keyboard switch (not shown). The channel control signal from the control oscillator 20 is generated. Is sent to the cable transmission system 12 via the demultiplexer 21 and the branching device 22 as the first upstream signal of the frequency f1 to the center 10. In addition, the monitoring terminal 1
3 is equipped with a television demodulator 23.

The television demodulator 23 receives the received television signal given as the second downlink signal of the frequency f2 'from the center 10 through the cable transmission system 12, the branching device 22 and the demultiplexer 21, and outputs the video and audio signals. The video demodulated by the TV demodulator 23 (Vide
The o) and audio signals are supplied to the monitor TV 24 for monitoring, which is, for example, a general-purpose AV TV receiver, and outputs video and audio. On the other hand, a control receiver 25 is provided on the terminal 11 side.

The control receiver 25 receives the channel control signal from the center 10 via the cable transmission system 12, the branching device 26, the demultiplexer 27, and the distributor 28 as the first downlink signal of the frequency f1 '. The channel control signal received by the control receiver 25 is supplied to the tunable television demodulator 29.

The tunable TV demodulator 29 monitors the multi-channel CATV TV signal supplied through the distributor 28 based on the channel control signal supplied from the control receiver 25. Tuning channel to the monitored channel specified by the terminal 13 for
Video of the TV signal of the selected monitored channel,
It demodulates into an audio signal, and the video and audio (A) demodulated and demodulated by this tunable television demodulator 29 are selected.
The udio) signal is supplied to the television modulator 30 for the upstream channel.

The TV modulator 30 for the upstream channel
Is for modulating the video and audio signals selected and demodulated by the tunable television demodulator 29 into a television signal again. The television signal from the television modulator 30 for the up channel is the frequency f2 to the center 10. Is output to the cable transmission system 12 via the demultiplexer 27 and the branching device 26.

FIG. 2 shows a frequency array of transmission signals in the above-mentioned bidirectional CATV monitoring device.
A plurality of CATV channels are assigned to the downlink signal from 0 as 1, 2, ..., N, and the return channel control signal from the monitoring terminal 13 to the terminal 11 is the first downlink signal f1 'and the terminal 11 From monitoring terminal 13
The return received television signal to is assigned as the second downlink signal f2 '.

The channel control signal is assigned to the upstream signal from the monitoring terminal 13 as the first upstream signal f1, and the upstream signal from the terminal 11 corresponds to the monitored channel. The selected received television signal is assigned as the second upstream signal f2.

FIG. 3 shows the internal structure of the control oscillator 20 in the bidirectional CATV monitoring device. The control oscillator 20 is composed of a control signal generator 20a and an FSK modulator 20b. ..

FIG. 4 shows the internal structure of the control receiver 25 in the above-described bidirectional CATV monitoring device. The control receiver 25 is composed of an FSK demodulation section 25a and a control signal reception section 25b. ..

FIG. 5 shows the internal structure of the tunable television demodulator 29 in the bidirectional CATV monitoring device. The tunable television demodulator 29 is the tuning unit 2.
9a and a demodulation unit 29b. The tuning unit 29a includes a buffer / PLL control circuit 29a1 and a local oscillation circuit 2
9a2, a tuning / mixing circuit 29a3, and an IF amplifier 29a4 are provided. Next, a terminal reception state monitoring operation of the bidirectional CATV monitoring device having the above configuration will be described.

First, the control transmitter 20 of the monitoring terminal 13
By using a keyboard switch (not shown) of the control signal generator 20a in
When a TV channel (monitored channel) is designated, a channel control signal having a transmission signal corresponding to this designated channel is generated. The channel control signal generated by the control signal generator 20a is used by the FSK modulator 2
The signal is modulated to the first downlink signal of frequency f1 via 0b and sent to the cable transmission system 12 via the demultiplexer 21 and the branching device 22.

From the monitoring terminal 13 to the cable transmission system 1
The first upstream signal (channel control signal) of frequency f1 transmitted to the center 10 via 2 is converted to the first downstream signal (channel control signal) of frequency f1 'through the first frequency converter 14. , To the return cable transmission system 12.

The first downlink signal of frequency f1 'transmitted from the center 10 to the terminal 11 via the cable transmission system 12 is fed from the distributor 28 to the FS of the control receiver 25.
After being demodulated into the channel control signal through the K demodulation unit 25a, waveform shaping and the like are performed through the control signal reception unit 25b, and the tunable television demodulator 29 is provided to the buffer / PLL control circuit 29a1 of the channel selection unit 29a. Supplied.

The buffer / PLL control circuit 29a1 controls the transmission frequency in the local transmission circuit 29a2 corresponding to the monitored channel based on the channel control signal supplied from the control receiver 25 through the control signal input terminal. The tuning / mixing circuit 29
At a3, a television signal corresponding to the monitored channel is tuned and tuned from the multi-channel CATV signal supplied through the RF input terminal, IF-amplified by the IF amplifier 29a4, and then demodulated. It is demodulated to a video (V) and audio (A) signal via 29b.

In this way, the video and audio signals corresponding to the TV signal of the monitored channel which are demodulated by the tunable TV demodulator 29 are supplied to the TV modulator 30 for the up channel and are again modulated into the TV signal. The second upstream signal of frequency f2 is sent to the cable transmission system 12 via the duplexer 27 and the branching device 26.

The second upstream signal (reception television signal) of frequency f2 transmitted from the terminal 11 to the center 10 through the cable transmission system 12 is transmitted through the second frequency converter 15 to the second signal of frequency f2 '. It is converted into a downlink signal (received television signal) and sent to the return cable transmission system 12.

Then, the second downlink signal of the frequency f2 '(received television signal corresponding to the monitored channel) transmitted from the center 10 to the monitoring terminal 13 via the loopback cable transmission system 12 is sent to the demultiplexer 21. Through the TV demodulator 23
Is supplied to the monitoring monitor television 24 after being demodulated into video (V) and audio (A) signals.

As a result, the television video and audio of the monitored channel received by the terminal 11 is output to the monitoring monitor television 24 of the monitoring terminal 13, and the terminal reception state is monitored on the cable transmission system 12. You can do it at any position.

Therefore, according to the bidirectional CATV monitoring device having the above configuration, the channel control signal having the transmission signal corresponding to the monitored channel is transmitted to the cable transmission system 12.
2 for controlling the monitoring terminal 13 provided at an arbitrary position of the
Based on the channel control signal which is transmitted from 0 to the cable transmission system 12 as the first upstream signal f1, frequency-converted into the first downstream signal f1 'at the center 10 and received by the control receiver 25 of the terminal 11, In the tunable television demodulator 29, the monitored CATV channel is tuned and tuned, and the television signal corresponding thereto is demodulated into a video signal and an audio signal.
At 0, it is again modulated into a television signal and sent out to the cable transmission system 12 as the second upstream signal f2, and the center 10 converts it back to the second downstream signal f2 'and transmits it back.
Since the configuration is such that the television demodulator 23 of No. 3 demodulates the video and audio signals and monitors the output on the monitor television 24
Received video and audio of any channel on the terminal 11,
It becomes possible to monitor in real time at any point on the CATV transmission path without using a dedicated line or the like.

In the above embodiment, the terminal 11 is provided with the tunable television demodulator 29 and the up channel television modulator 30, and the channel is demodulated on the basis of the channel control signal received by the control receiver 25. The video and audio signals corresponding to the monitored channel are again modulated into television signals and sent to the center 10 as the second upstream signal f2. However, as shown in FIG. 6, the tunable television demodulator 29 is used. And a tunable channel converter 31 instead of the upstream channel TV modulator 30
The television signal corresponding to the monitored channel selected based on the channel control signal may be directly frequency-converted into the second upstream signal f2 without being demodulated and transmitted to the center 10.

FIG. 7 shows the internal structure of the tunable channel converter 31 shown in FIG. 6, and the tunable channel converter 31 has a tuning unit 31a having the same structure as the tuning unit 29a of the tunable television demodulator 29. On the other hand, it is configured only by adding the channel converter 31b.

That is, based on the channel control signal received by the control receiver 25, the television signal corresponding to the monitored channel tuned and tuned by the tuning unit 31a is the second one of the frequency f2 by the channel converter 31b. The signal is frequency-converted into an upstream signal and is sent to the center 10.

Also in this case, the terminal 1
It becomes possible to monitor the received video and audio of the arbitrary channel in No. 1 in real time at the monitoring terminal 13 provided at an arbitrary position of the cable transmission system 12 without using a dedicated line or the like.

In the above embodiment, the monitoring terminal 13 and the terminal 11 are described as one-to-one folded by the center 10. However, for example, a plurality of terminal devices are installed in the cable transmission system 12. Even in such a case, if the terminal address is set to each terminal and the address data is added to the channel control signal from the monitoring terminal 13, the plurality of terminal devices are sequentially called, and each of them is called. It becomes possible to finely monitor the terminal reception state in each case.

Further, the control oscillator 2 in the above embodiment
The FSK modulation method was used as the 0 modulation method, but in short, other modulation methods will not cause any problems as long as they are suitable for the purpose of transmitting the channel control signal at a high frequency.

[0040]

As described above, according to the present invention, in the bidirectional CATV transmission system for bidirectionally transmitting the television signal between the center side and the terminal side via the cable transmission system, the above-mentioned cable transmission system is used. A monitoring terminal that is branched and connected to an arbitrary position to monitor the terminal reception state, and a channel control signal that is provided in this monitoring terminal and that corresponds to the designation of the monitored channel is generated to generate a first upstream signal f1 in the cable transmission system. A control oscillator for sending and a channel control signal provided on the center side as the first upstream signal f1 from the controlling oscillator, which is converted to a first downstream signal f1 'and sent to the cable transmission system. 1 frequency converter, a control receiver provided on the terminal side for receiving a channel control signal as the first downlink signal f1 'from the first frequency converter, and this control receiver A tunable television demodulator that tunes the receiving channel on the terminal side to the specified channel based on the channel control signal received by the demodulator and demodulates the television signal into a video and audio signal, and a demodulated signal from this tunable television demodulator An up-channel television modulator which modulates a signal and sends it out to the cable transmission system as a second up-signal f2, and a second up-signal f from the up-channel television modulator provided on the center side.
A second frequency converter for converting the television signal set to 2 into a second downlink signal f2 'and sending it to the cable transmission system, and a second frequency converter provided in the monitoring terminal and provided from the second frequency converter.
Since it is configured to include a television demodulator that demodulates the television signal that is the downlink signal f2 'into video and audio signals, and a monitoring monitor television that outputs video and audio according to the demodulated signal from this television demodulator, It is possible to monitor video and audio corresponding to all reception channels in real time from an arbitrary position on the CATV transmission path without laying a dedicated monitoring line for a target terminal.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a bidirectional CATV monitoring device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a frequency array of transmission signals in the bidirectional CATV monitoring device.

FIG. 3 is a block diagram showing an internal configuration of a control transmitter in the bidirectional CATV monitoring device.

FIG. 4 is a block diagram showing an internal configuration of a control receiver in the bidirectional CATV monitoring device.

FIG. 5 is a block diagram showing an internal configuration of a tunable television demodulator in the interactive CATV monitoring device.

FIG. 6 is a block diagram showing another embodiment of the terminal-side configuration of the bidirectional CATV monitoring device.

FIG. 7 is a block diagram showing an internal configuration of a tunable channel converter in another embodiment of the bidirectional CATV monitoring device.

[Explanation of symbols]

10 ... CATV sending center, 11 ... Terminal, 12 ... Cable transmission system, 13 ... Monitoring terminal, 14 ... First frequency converter, 15 ... Second frequency converter, 16, 21, 27 ... Divider, 17, 28 ... Distributor, 18, 19 ... Mixer, 20
Control oscillator, 20a Control signal generator, 20b F
SK modulator, 22, 26 ... Divider, 23 ... TV demodulator, 24 ... Surveillance monitor TV, 25 ... Control receiver,
25a ... FSK demodulator, 25b ... Control signal receiver, 29
... Tunable TV demodulator, 29a, 31a ... Channel selection section, 29a1 ... Buffer / PLL control circuit, 29a2 ... Local oscillation circuit, 29a3 ... Tuning / mixing circuit, 29a4 ... IF amplification section, 29b ... Demodulation section, 30 ... Upstream channel TV modulator, 31 ... Tunable channel converter, 31
b ... Channel converter.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naohiko Senda 1406 Hasunuma, Omiya City, Saitama Yagi Antenna Co., Ltd. Omiya Plant (72) Inventor Masao Suenaga 1406 Hasunuma, Omiya City, Saitama Yagi Antenna Co., Ltd. Omiya Plant ( 72) Inventor Kiyoshi Nishiaki 3-18-39 Oyodochu, Kita-ku, Osaka City, Osaka Prefecture Kansai Cable Service Co., Ltd. (72) In-house Yasuo Noda 1-21-1 Kasugaoka, Itami City, Hyogo Prefecture

Claims (2)

[Claims] 1. A bidirectional CATV for bidirectionally transmitting a television signal between a center side and a terminal side via a cable transmission system.
In the monitoring device for monitoring, a monitoring terminal that is branched and connected to an arbitrary position of the cable transmission system to monitor the terminal reception state, and a channel control signal that is provided on the monitoring terminal and that generates a channel control signal according to the designation of the monitored channel is generated. A control oscillator which sends out to the cable transmission system as one upstream signal f1 and a channel control signal which is provided as a first upstream signal f1 from the above-mentioned control oscillator on the center side, and a first downstream signal f1.
A first frequency converter for converting to 1'and sending it to the cable transmission system; and a first frequency converter provided on the terminal side from the first frequency converter.
A control receiver for receiving a channel control signal which is a downlink signal f1 ', and a terminal side reception channel is tuned to the designated channel based on the channel control signal received by the control receiver, and the television signal is video and audio. A tunable television demodulator for demodulating into a signal, an up channel television modulator for modulating a demodulated signal from this tunable television demodulator into a television signal and sending it as the second upstream signal f2 to the cable transmission system, and the above center. A second frequency converter provided on the side for converting the television signal as the second upstream signal f2 from the upstream channel television modulator into a second downstream signal f2 'and sending it to the cable transmission system; A terminal provided in the terminal for demodulating a television signal as the second downlink signal f2 'from the second frequency converter into a video and audio signal. A bi demodulator, this television image corresponding to the demodulated signal from the demodulator, bi-directional CATV surveillance apparatus characterized by comprising a monitoring monitor TV for outputting audio, a. 2. A bidirectional CATV for bidirectionally transmitting a television signal between a center side and a terminal side via a cable transmission system.
In the monitoring device for monitoring, a monitoring terminal that is branched and connected to an arbitrary position of the cable transmission system to monitor the terminal reception state, and a channel control signal that is provided on the monitoring terminal and that generates a channel control signal according to the designation of the monitored channel is generated. A control oscillator which sends out to the cable transmission system as one upstream signal f1 and a channel control signal which is provided as a first upstream signal f1 from the above-mentioned control oscillator on the center side, and a first downstream signal f1.
A first frequency converter for converting to 1'and sending it to the cable transmission system; and a first frequency converter provided on the terminal side from the first frequency converter.
A control receiver for receiving a channel control signal as a downlink signal f1 ', and a terminal side reception channel is tuned to the specified channel on the basis of the channel control signal received by the control receiver, and the television signal is transmitted to the second upstream side. A tunable converter that sends out as a signal f2 to the cable transmission system, and a television signal that is provided as a second upstream signal f2 from the tunable converter on the center side, is converted into a second downstream signal f2 ', and the cable transmission is performed. A second frequency converter for sending to the system, and a television demodulator provided in the monitoring terminal for demodulating a television signal as a second downlink signal f2 'from the second frequency converter into video and audio signals. A bidirectional monitor comprising a monitor TV for monitoring, which outputs video and audio according to a demodulated signal from a TV demodulator. ATV for monitoring device.