JPH11295471A - Monitoring system in nuclear power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monitoring system in a nuclear power plant capable of using an already set control cable or the like to a transmission path without using a video band cable, simply setting an image monitor at a desired site, easily removing them, and suitable for temporary set use. SOLUTION: An image signal photographed by a video camera 10 is encoded into a digital signal compressing the image data amount by an encoder 12, and modulated to a signal suitable to the frequency band of a transmission path 2 by an ADSL modem 13 to be transmitted. Therefore, the transmission path 2 in which the frequency band is narrow and a communication capacity is small, for instance, the image data can be transmitted even by the already set telephone line and the control cable, and a video band cable need not be newly set. The image monitor 3 in a receiving side corresponds to an image transmission device 1 in a transmitting side, the signal fetched from the transmission path 2 is demodulated, extended, decoded, returned to the image signal and displayed on the monitor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear power plant for transmitting image data through a transmission line having a narrow frequency band and a small communication channel capacity, such as a telephone line or a control cable already installed in a section where image transmission is desired. The present invention relates to a monitoring system in a power plant, and more specifically, to a monitoring system in a nuclear power plant adapted to adapt to the transmission line by encoding and modulating an image signal.

[0002]

BACKGROUND OF THE INVENTION When monitoring in a nuclear power plant,
A video camera for ITV (industrial television) and an image transmission device (terminal equipment) including a control device for transmitting image data captured by the video camera are installed in the monitoring area (site), and a point away from the site. A monitor for image monitoring is installed in the central control room provided in the above, and a dedicated coaxial cable is installed between the monitor and the central control room to transmit image signals.

[0003] Thus, for example, image data captured by the video camera in a specific area such as a restricted access area can be displayed on a monitor in a central control room via a coaxial cable, and monitoring is performed by looking at the monitor. ing.

In this case, a video camera for monitoring images is
Although important areas are located, they do not cover the entire area of the industrial facility. For this reason,
If an abnormality occurs in an area where a video camera for image monitoring is not provided, it is difficult to grasp the current situation in the central control room only by contacting the site where the abnormality has occurred with a local telephone or the like. In addition, monitoring is apt to be inadequate, as it is not possible to have personnel on site only for telephone calls.
Therefore, ideally, when an abnormality occurs, an image transmission device including a video camera is immediately installed at the site where the abnormality has occurred, and a new transmission path (such as a coaxial cable) is provided between the apparatus and the central control room. It is necessary to install a dedicated cable to transmit image signals.

However, in practice, installing a dedicated cable for transmitting a signal in the video band between the site where image monitoring is desired and the central control room requires a detour to the restricted area in the facility. For this reason, the installation distance becomes long, which is troublesome and costly.
In particular, where there are many restricted access areas such as nuclear power plants, if a new dedicated cable is to be installed between the abnormal occurrence area of the nuclear power plant and the main control room, the actual installation should be performed for the straight line distance by detour. The increase in distance becomes very large, and the installation cost and the cost of a dedicated cable become high. Further, as the installation distance increases, the time required for the installation work also increases, so waiting for the installation may cause a delay in quickly grasping / analyzing an abnormal situation and performing a recovery work. In addition, until the installation is completed, it is still necessary to grasp the inadequate current situation by contact using a private telephone or the like, so that it is also difficult to quickly respond.

On the other hand, if the abnormal state is eliminated, the installed equipment is removed and collected because the image monitoring is no longer necessary. However, it takes time and effort to perform the removal work. Therefore, only the image transmission device is removed, and the dedicated cable once set is left as it is. Then, the neglected dedicated cable is “dedicated” as its name implies, and if an abnormality occurs accidentally in the same place, it remains as an unnecessary object that is not normally used anyway. Leaving such useless facilities in the facility is not only a hindrance, but is also undesirable in terms of effective use of resources.

As described above, in a nuclear power plant, a system for temporarily transmitting a moving image at the time of an abnormality can be easily and quickly constructed, and the system can be easily removed when the system is no longer required, such as when the abnormality is resolved. For many years, it has been desired to develop a system in which the removed equipment can be reused in other places.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and an object of the present invention is to solve the above-mentioned problem and to use an existing control cable or the like without using a dedicated cable for a video band. It can be easily installed at the site where image surveillance is desired, and can be easily removed when image surveillance becomes unnecessary, providing a monitoring system suitable for temporary use in a nuclear power plant. It is in.

[0009]

In the technical field of communication, NTSC video signals are usually used for image transmission, but coaxial cables suitable for transmission of large amounts of information are used due to the large amount of information. Have been. When a communication metal cable other than a coaxial cable is used as a transmission line, the transmission distance is short (up to several hundred meters), the effect of ghost and noise by a bridge tap is large, and the transmission capability is inferior, so that it cannot be used.

In the technical field of communication, it is generally recognized that the technology of the control cable and the technology of the communication line are different technologies, so that it is considered to use the control cable as a communication transmission line. Absent. For this reason, a large number of control cables such as nuclear power plants are installed, and although there are unused core wires that are not normally used for spare, they are used as transmission lines for communication. No effort has been made.

In an industrial facility such as a nuclear power plant, telephone lines are networked throughout the premises, and control cables and the like extend from various parts of the premises to the central control room and are already installed. There are a number of unused spare core wires not used in the control cable and the like. Therefore, if a signal in the video band can be transmitted through a private telephone line and a control cable, installation and removal of a dedicated cable becomes unnecessary, which is convenient. However, such a telephone line or control cable has a narrow frequency band and a small communication path capacity. Therefore, signal transmission in the video band cannot be performed.

The present invention relates to a permanent ITV in a nuclear power plant.
If an abnormality occurs in a place where is not installed, use a spare core cable or telephone line that is not normally used for spare among the control cables installed between each place in the nuclear power plant and the main control room. Tried to use it as a cable for ITV. Further, as described above, a technique for transmitting a video without any trouble is devised by devising a means for preventing a bridge tap or a ghost that would be clearly caused by simply using a control cable or a telephone line.

In order to solve the above problems, the amount of information flowing through the control cable is made as small as possible.
While paying attention to developing a technology that can easily transmit a small amount of information to the upstream, among the components of the video-on-demand (VOD) component recently developed in the United States, ADSL (Asymmetric Digit
al Subscriber Line) I noticed that there was a modem that could transmit a small amount of information, and combined this modem with an image compression device, a camera, a communication device, etc., and made it an ITV that could be carried to the site of a nuclear power plant to be monitored. Then, by using the existing control cable between the site in the nuclear power plant and the monitoring room as a video transmission line, the new control cable can be carried to the site to be monitored without installing any new dedicated cable. By simply placing it on a video transmission system, it can be used immediately as an ITV. The specific configuration is as follows.

The image transmission apparatus includes an image transmission device installed in a monitoring area in a nuclear power plant, and a transmission line connecting the image transmission device and a monitoring device installed in a remote place. And the image transmission device, a video camera for imaging a monitoring area,
An encoder for compressing image data captured by the video camera and an ADSL modem for modulating the image data compressed by the encoder and outputting the modulated data to the transmission path are provided. Further, the transmission line is formed of a two-core wire of a metal cable. Further, the monitoring device includes an ADSL modem connected to the transmission line and a decoder for expanding image data transmitted from the image transmission device (in the embodiment, the monitoring device is incorporated as a part of the function of the personal computer 32). ) And output means (corresponding to a “monitor” in the embodiment) for outputting the decompressed image data (claim 1).

According to the present invention, an image signal captured by a video camera is encoded into a digital signal in which the amount of image data is compressed by an encoder, and is modulated by an ADSL modem into a signal adapted to the frequency band of the transmission path. Will be sent out. Therefore, image data can be transmitted even on a transmission path having a narrow frequency band and a small communication path capacity. Moreover, since the two-core wire can be used by using the ADSL modem, the image signal can be transmitted through the already installed transmission line such as a telephone line or a control cable. Therefore, there is no need to newly install a dedicated cable for the video band.

Since the monitoring device on the receiving side is configured to correspond to the image transmitting device on the transmitting side, it is possible to demodulate, expand and decode the signal fetched from the transmission path,
The transmitted image data can be returned to an image signal and displayed on output means such as a monitor.

In the present invention, since the image data is one-way communication transmitted only from the downstream image transmission device to the upstream monitoring device, a codec (image compression device) used in a video conference system is constituted. Encoder (image compression device) and decoder (image decompression device)
Only necessary functions were extracted and implemented.
As a result, the configuration can be simplified and downsized, and the cost can be reduced. Further, since the ADSL modem is used, the transmission distance can be increased.

On the premise of the above-mentioned system, control signals from the monitoring device to the image transmission device are modulated and demodulated by the two ADSL modems and transmitted via the transmission line. It is better to do so (claim 2). That is, the image data is given from the downstream image transmission device to the upstream monitoring device, and the control signal is sent from the monitoring device to the image transmission device side. And ADSL
By using a modem, data communication with a different transmission data amount depending on the transmission direction is possible, so that image data can be sent from the image transmission device as described above, and a control signal can be sent in the opposite direction. Moreover, by selecting the carrier frequency, multiplex transmission becomes possible, and a control signal is sent to the imaging means while viewing the transmitted image, so that the imaging area can be changed.

The transmission line uses a control cable or a vacant line of a telephone line already installed in the nuclear power plant, and installs the image transmission device at a place where a monitoring request is issued and connects to the vacant line. By connecting the monitoring device and the image transmission device, data transmission and reception are performed, and when there is no monitoring request, the image transmission device is removed from the transmission path, thereby installing the image transmission system. -Release can be arbitrarily performed (claim 3).

The use of an existing cable or other empty core eliminates the trouble of installing a dedicated line as in the prior art. Therefore, when an abnormality occurs, the image transmission apparatus is brought to the site where the abnormality has occurred, and the site where the abnormality has occurred is located. An image transmission system can be easily constructed by connecting (connecting) to a control cable or a vacant line of a telephone line which is already wired. Therefore,
Monitoring with images can be performed immediately, and appropriate processing can be performed quickly. Further, when the monitoring is no longer necessary due to the elimination of the abnormal situation, the removal operation is completed simply by removing the connected image transmission device. And since the transmission line originally uses existing wiring, there is no problem if it is left as it is, and the removed image transmission device is
It can be reused by taking it to another monitoring area and installing it.

[0021]

FIG. 1 is a block diagram showing an embodiment of a monitoring system in a nuclear power plant according to the present invention.
As shown in the figure, the image transmission device 1 is a video camera 1
0, control unit 11, encoder 12, ADSL modem 13
Is connected to the transmission line 2 and image data is transmitted through the transmission line 2. That is, the image signal captured by the video camera 10 is
2 and is encoded into a digital signal by the encoder 12 to compress the amount of image data. And
This digital signal is input from the encoder 12 to the ADSL modem 13, where it is modulated in accordance with the frequency band of the transmission line 2 and sent out to the transmission line 2.

The transmission line 2 is a parallel two-core wire such as a telephone line, and has a narrow frequency band and a small communication path capacity. For example, a control cable may be used, and a so-called video band signal such as a coaxial cable or an optical fiber cable may be used. There is no need to use a broadband communication cable for transmission. That is, as the transmission line 2, a spare core wire (empty core) such as a private telephone line and a control cable already installed in the nuclear power plant may be used.

On the receiving side such as the central control room, the image monitoring device 3 is connected to the transmission line 2 installed in the room, and the transmitted image signal is displayed on the monitor 30 of the image monitoring device 3. That is, the image monitoring device 3 includes the monitor 30, the personal computer 32, and the ADSL modem 33 and is connected to the transmission line 2, and returns image data transmitted through the transmission line 2 to an image signal. ing.

The simple exchange 4 is connected to the ADSL modem 33. A telephone 5 is connected to the simplified exchange 4. The telephone 5 is also connected to the ADSL modem 13 on the transmitting side, such as a monitoring site, so that the two can talk.

The ADSL modems 13 and 33 are provided by Asymm
Etric Digital Subscriber
It is a modem for Line, performs modulation and demodulation of the so-called DMT system, and is configured to enable high-speed communication of several Mbit / sec over a telephone line. What is DMT
This is an abbreviation for "ete Multi Tone". According to this method, the influence of crosstalk on other transmission cables is hardly affected, and the influence of crosstalk is hardly affected.

The ADSL modems 13 and 33 change the frequency band according to the signal to be transmitted, and can perform multiplex transmission. Specifically, as shown in FIG. 2, a telephone signal uses 3.4 kHz, a camera control signal uses 9.6 kHz, and an image data signal uses 100 to 500 kHz.

The control unit 11 is configured to decode a camera control signal sent from the ADSL modem 13 and output a drive signal corresponding to the control command to the video camera 10. , The zoom, pan, and tilt of the video camera 10 are controlled.

The encoder 12 encodes an input image signal into a digital signal. The encoder 12 encodes the image signal according to the RVC standard conforming to the standard called MJPEG, and converts the image signal to 96 Kbytes or less per screen. Compression, and the band compression ratio of the image signal is 1/10 to 1/2.
00.

In the image monitoring device 3 on the receiving side, decompression and decoding are performed by the personal computer 32.
The digital signal passed from the DSL modem 33 is expanded or decoded in hardware or software. That is, in the personal computer 32,
A decoder board for expanding and decoding the input signal is mounted, and a software program for decoding is also incorporated, so that one of them can be selected by switching. Also, a software program for controlling the camera is incorporated in the personal computer 32, and a camera control signal for controlling the video camera 10 is transmitted to the ADS.
Output to the L modem 33.

The transmission path 2 is 0.9 mm CPEV.
It was confirmed by experiments that transmission over a distance of 8 km was possible without any problem. At this time, the resolution of the image was good and 640 dots × 480 dots.

According to such a configuration, the video camera 1
The image signal taken at 0 is encoded by the encoder 12 into a digital signal whose image data amount is compressed, and is modulated by the ADSL modem 13 into a signal suitable for the frequency band of the transmission path 2 before being sent out. Therefore, image data can be transmitted even on the transmission path 2 having a narrow frequency band and a small communication path capacity. That is, since the image signal can be transmitted through the transmission line 2 already installed, such as a telephone line or a control cable, it is not necessary to newly install a dedicated cable for the video band.

The image monitoring device 3 on the receiving side has a configuration corresponding to the image transmitting device 1 on the transmitting side.
The signal captured from the transmission path 2 can be demodulated and decompressed and decoded, and the transmitted image data can be returned to an image signal and displayed on the monitor 30.

As described above, an existing telephone line, control cable, or the like can be used as the transmission line 2 without using a video band cable. Such a telephone line, control cable, or the like is installed at various locations in the facility. It is easy to find out where the image monitoring is desired, and there is no hesitation in finding it. Therefore, the image transmission apparatus 1 can be easily installed at a site where image monitoring is desired, and there is no need to install a dedicated cable, so that image monitoring can be performed quickly. When the image monitoring becomes unnecessary, it can be easily removed and is suitable for temporary use.

It should be noted that monitoring of an image may be configured as shown in FIGS. FIG. 3 shows a configuration in which the image monitoring device 3 is also installed in the second monitoring room. The modulated signal is through-branched as it is so that image monitoring is performed at two places.

FIG. 4 shows a configuration for monitoring an image at a plurality of locations.
While being connected to the AN 34, the personal computer 32 and the monitor 30 are connected to the LAN 34 at a plurality of locations, and the demodulated digital signal is transmitted from the ADSL modem 33 to the personal computer 32 at each location.

[0036]

As described above, according to the present invention, since the image signal can be transmitted through the already installed transmission line such as a telephone line and a control cable, a dedicated cable for the video band is newly installed. No need. Since telephone lines, control cables, and the like used as transmission lines are installed at various places in the facility, it is easy to find them at the site where image monitoring is desired, and there is no hesitation in finding them. Therefore, the image transmission apparatus can be easily installed at the site where image monitoring is desired, and there is no need to install a dedicated cable for the video band, so that image monitoring can be performed quickly. When the image monitoring is no longer required, it is easy to remove the image, which is advantageous for temporary use. Also, there is nothing to waste after removal,
Effective use of resources can also be achieved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram of a frequency band indicating a transmission band of an ADSL modem.

FIG. 3 is a configuration diagram illustrating another embodiment of the present invention.

FIG. 4 is a configuration diagram illustrating another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image transmission apparatus 2 Transmission path 3 Image monitoring apparatus 10 Video camera 12 Encoder 13, 33 ADSL modem 30 Monitor (output means) 32 Personal computer (decoder)

Claims (3)

[Claims] An image transmission device installed in a monitoring area in a nuclear power plant, and a transmission line connecting the image transmission device and a monitoring device installed in a remote location, wherein the image transmission device monitors A video camera that captures an image of an area, an encoder that compresses image data captured by the video camera, and an ADSL modem that modulates the image data compressed by the encoder and outputs the modulated data to the transmission path. The path comprises a two-core wire of a metal cable; the monitoring device comprises an ADSL modem connected to the transmission line, a decoder for expanding image data sent from the image transmission device, and a decompressed image. A monitoring system in a nuclear power plant, comprising: output means for outputting data. 2. A control signal from the monitoring device to the image transmission device is modulated and demodulated by the two ADSL modems and transmitted via the transmission line. Item 2. The monitoring system in a nuclear power plant according to Item 1. 3. The transmission line uses a power control cable or a vacant line of a telephone line already installed in a nuclear power plant, and installs the image transmission device at a location where a monitoring request is generated. By connecting to the vacant line, the monitoring device and the image transmission device are connected to transmit and receive data, and when there is no monitoring request, the image transmission device is detached from the transmission path, so that the image is transmitted. 3. The monitoring system in a nuclear power plant according to claim 1, wherein the transmission system can be installed and released arbitrarily.