JPH0287790A - Remote monitor system - Google Patents

Abstract

PURPOSE:To monitor lots of picture signals remotely through the use of a TV transmission line by varying the frequency by the remote control from the reception side in the case of multiplexing the content of each frame memory storing picture information at the sender side. CONSTITUTION:Each output picture signal from plural ITV cameras 1-1'' is stored in frame memories 3-3'' as picture information by one frame sequentially. It is subject to time division multiplex by a multiplexer circuit 11 and sent as an optical signal through an optical fiber 20 from an optical transmitter 12 and received by an optical receiver 13. The signal is demultiplexed for each channel by a multiplexer/demultiplexer circuit 14, stored in frame memories 4-4'' and displayed on monitors 6-6''. The frequency of multiplexing from an operation console 7 is varied in response to the ratio of the change in the pattern in the case of multiplexing the content of the frame memory sequentially in this case. Thus, monitoring by using lots of monitors is attained without a sense of unnaturality due to the picture change.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a remote monitoring system, and in particular, a remote monitoring system suitable for transmitting and monitoring a large number of image signals. In processing equipment, centralized remote monitoring and control systems have been put into practical use that multiplex and transmit digital signals such as valve opening/closing information and analog measured values such as liquid level. The information rate of these is slow, and even if multiplexed, the transmission rate is at most several Mb/s or less.

On the other hand, in these remote monitoring systems, in addition to the conventional numerical information (digital signals and analog instrumentation) mentioned above,
There is an increasing demand for transmitting image information from ITV cameras and the like for monitoring using a single image. In order to prevent screen flickering, image signals are transmitted at more than 30 frames per second (one frame is one screen), resulting in a wideband signal exceeding several MHz per channel. For this reason, long-distance monitoring systems that involve the transmission of images use a wide-bandwidth video transmission line, and multiple transmission lines are also used to transmit multiple images, which increases the cost of the transmission line. . In order to unify the transmission path, a wavelength division multiplexing transmission system can be used, for example, as described in the document ``Optical Communication System'' (edited by the Television Society of Japan). FIG. 3 shows its block diagram. That is, image signals from multiple cameras l-1'' are transmitted with different wavelengths (λ, ~λ4
) The optical transmitters 16 to 16'' convert the signal into an optical signal, and the optical multiplexer 18 sends it out into one optical fiber 20. On the receiving side, the optical demultiplexer 19 demultiplexes the signal into each wavelength. , optical receiver 17~
The original image signal is generated at 17#' and displayed and monitored on monitors 6 to 6#'. This makes it possible to transmit a plurality of image signals through one transmission path (optical fiber).

[Problem to be solved by the invention]

The above-mentioned conventional technology is characterized by the use of wavelength multiplexing of light, but in the current optical fiber communication technology using the wavelength band of 0.8 to 1.5 μm, the wavelength of the light source and the characteristics of the optical multiplexer/demultiplexer , it is possible to multiplex only 4 to 5 channels at most. Further, the optical multiplexer/demultiplexer is also expensive, and there is a problem in that the cost of the transmission line increases.

Note that there is also a method in which a plurality of image signals are switched and transmitted through a single transmission path, but this method has the disadvantage that it is not possible to monitor and monitor a large number of images at the same time.

An object of the present invention is to provide a remote monitoring system that can transmit a plurality of images through a single transmission path and simultaneously monitor them on multiple monitors while keeping the cost of the transmission path low.

[Means to solve the problem]

The above purpose effectively utilizes the following two features of the monitoring image information.

(1) Monitoring images of ordinary facilities and plants, such as water and sewage treatment facilities, often show little change on the screen.

(2) Even in monitoring images of the same equipment or plant, there are some that have many changes on the screen and others that have few changes.

Therefore, one frame (one screen) of each image is stored in memory, and this is time-division multiplexed.

The above objective can be achieved by transmitting images with many changes more frequently than images with many changes.

[Effect]

That is, in order to prevent screen flickering, normal image signals are sent at 30 frames (screens) or more per second. However, if the image changes at a rate of about once per second, for example, by rewriting the screen memory for one frame every second and displaying this repeatedly on the monitor, flickering can be eliminated. Moreover, it is possible to obtain a monitoring screen that does not look unnatural. Therefore, if the screen looks like this.

By sequentially time-division multiplexing one frame of each of the 30 images, the 30 images can be transmitted over one transmission path without increasing the transmission speed.

On the other hand, depending on the type of monitoring image, some images change once every 0.5 seconds, while others only need to be monitored once every 30 seconds. In this case as well, efficient transmission is possible by changing the frequency of time division multiplexing according to the changing characteristics of one screen.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. Each output image signal from a plurality of ITV cameras 1 to 1' is digitized by AD converters 2 to 2'' and stored in frame memories 3 to 3.
'The image information for one frame is sequentially stored in the memory.

This is time-division multiplexed by a multiplexing circuit 11, and an optical transmitter 12
The signal is converted into an optical signal by the optical receiver 13, and after being optically transmitted by the optical fiber 20, it is returned to the original electrical signal by the optical receiver 13. This is separated for each channel by the demultiplexing circuit 14 and stored in the frame memories 4 to 4'. The contents of this memory are converted into a normal NTSC image signal by a video display generator (VDG) 5~5''.

It is displayed on the monitors 6-61.

On the other hand, the control signal from the console installed on the monitor side,
After the light is transmitted to the camera side by the control unit 15, the optical transmitter 12', the optical fiber 20', and the optical receiver 13', the control unit 15
' controls the multiplexing method of the multiplexing circuit 11. FIG. 2 shows an example of the structure of the signal after multiplexing. Figure 2(a) shows 1,
2. . . . This is a case where the change characteristics of image signals from n ITV cameras up to n are almost equal, and the contents of each frame memory 41, 42 . ...4n are sequentially multiplexed. Note that 31.32. in Figure 1. ...3n is address information indicating the delimiter of each frame and which terminal it corresponds to.

FIG. 2(b) shows a case where only the image from the ITV camera 1 changes drastically, and the content 41 of the frame memory based on the image signal from the camera 1 is transferred to the other frame memories 42 to 4n.
It is sampled more frequently and multiplexed.

In this way, when the contents of the frame memory are sequentially multiplexed, the frequency of multiplexing from the console is changed depending on the rate of change of the screen. As a result, the monitor who monitors the monitors can monitor multiple monitors at the same time without feeling unnatural due to changes in the screen.

Please note that information other than image information in the remote monitoring system (
Digital contact signals such as valve opening/closing signals and analog instrumentation quantities such as liquid level etc.) do not change much and contain less information than images. Therefore, in the embodiment shown in FIG. 1, the above-mentioned information is once multiplexed in the multiplexing circuit 22 (of course, the analog instrumentation amount is multiplexed after being digitized), and then stored in the buffer memory 23. Digital contact signals are generated by multiplexing the contents of this memory in a manner similar to one of the other image frame memories.

A wide variety of signals with different types and amounts of information, such as analog instrumentation and image information, can be multiplexed and transmitted using the same architecture.

In addition, according to this embodiment, since optical communication technology is used as the video transmission path, there is also the effect that it is not affected by the ground potential difference between the transmitter and the receiver and the electromagnetic noise in the transmission path.

〔Effect of the invention〕

According to the present invention, a large amount of image information, analog instrumentation, etc. can be sent using one video transmission line that transmits one channel of normal images.

For example, an image signal based on the normal NTSC system sends 30 frames (screens) per second, so the band is 4.
It becomes 2MHz. If this is sampled at 9 MHz and expressed as 8 bits, then 72 MHz per channel of the image.
A b/s digital transmission line is required. Therefore, according to the present invention, if the image changes only about once per second, 30 channels of images can be transmitted over the same transmission path and displayed on the monitor at the same time, thereby forming an economical transmission path. be able to.

Also, if the image change characteristics of each channel are different,
By making the frequency of multiplexing variable from the console,
You can get a screen that looks natural.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing an embodiment of a remote monitoring system according to the present invention, Fig. 2 is a configuration diagram of a transmission signal according to the present invention, and Fig. 3 is an image obtained by a conventional wavelength multiplexing system. FIG. 2 is a block diagram showing a transmission method. 1...ITV camera, 2...AD converter. 3.4... Frame memory, 5... Video display generator, 6... Image monitor, 7...
Operation console, 11... multiplexing circuit, 12... optical transmitter,
13... Optical receiver, 14... Body weight separation circuit, 15.
...Control unit, 20.. Optical fiber, 31.. Address information, 41.. Contents of frame memory, 18.. Optical multiplexer, 19.. Optical demultiplexer.ゝ(''/ 躬圀大? Figure 7 round 2 to 1 庬

Claims (1)

[Claims] 1. In a remote monitoring system that transmits multiple pieces of image information, the transmitting side has multiple frame memories that store image signals from multiple television cameras, etc., and the contents of the frame memories are multiplexed. Provide a multiplexing device,
In the multiplexing device, the receiving side is provided with a number of frame memories corresponding to each of the image information described above, a television monitor, and a demultiplexing device for separating signals from the multiplexed signal into the plurality of frame memories described above, A remote monitoring system characterized in that the frequency of multiplexing the contents of each frame memory is made variable by an operation from the receiving side.