JPH02105789A - Video transmitter - Google Patents

Abstract

PURPOSE:To transmit video signals in multiple channels through one transmission line by sending the video signals from TV cameras after respectively modulating the signals by means of modulators with different modulating frequencies. CONSTITUTION:Variable modulators 221-225 which variably modulate video signals from TV cameras 211-215 with modulating frequencies controlled by a central processor (CPU) 27 are provided. The CPU 27 sends the video signals to a transmission line 28 after respectively modulating the video signal with different modulating frequencies by controlling the modulators 211-215 to respectively modulate the video signals with different frequencies. Therefore, the video signals can be transmitted in multiple channels through one transmission line 28.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a video transmission device used in a TV system, a video conference system, an independent broadcasting system, etc.

BACKGROUND ART Conventionally, when images from multiple television cameras are selectively switched and monitored on a television, such as in a TV system, each camera 111 to 113 becomes a video transmission path, as shown in FIG. The coaxial lines 12t to 123 are disposed inside a conduit in a building, and the video signals from the cameras 111 to 113 are selectively switched by a switcher 13 and monitored on a television 14.

In other conventional video transmission devices, one transmission path is frequency-division multiplexed or time-division multiplexed, each transmission channel is fixedly assigned to each television camera in advance, and each television camera is connected by selecting a channel on the transmission path. The system is configured to selectively monitor images from the computer.

Problems to be Solved by the Invention However, in the former video transmission device described above, each time a camera is added, a coaxial line must be installed in the conduit between the camera and the switcher. The problem is that it lacks flexibility and expandability for construction.

On the other hand, in the latter video transmission device, one transmission path is multiplexed, so the above problem can be solved.
Since the transmission channel is fixedly assigned, there is a limit to the number of videos that can be transmitted, and it is difficult to use this transmission path as a transmission path for signals of other systems due to the configuration of the equipment. In view of the above-mentioned conventional problems, it is an object of the present invention to provide a video transmission device having flexibility and expandability.

Means for Solving the Problems In order to achieve the above object, the present invention provides a plurality of modulators that modulate video signals from a television camera at variable frequencies, and each modulator modulates and transmits a video signal at a different frequency. It is designed to be sent out onto the street.

Effect of the Invention With the above configuration, the present invention can transmit video signals in multiple channels through one transmission path, and also provides flexibility by dynamically allocating channels by changing the modulation frequency of each modulator. It is possible to realize an expandable video transmission device.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a video transmission device according to the present invention, and in this embodiment, an ITV system and a video conference system are combined.

In FIG. 1, 21+ to 213 are each equipped with a television camera of the ITV system, 221 to 223 are each equipped with a frequency synthesizer, and a central processing unit (CP), which will be described later, is equipped with a frequency synthesizer.
U) A variable modulator 231 that variably modulates video signals from the television cameras 211 to 213 with a modulation frequency controlled by 27;
24. a demodulator for an ITV system that selectively demodulates video signals transmitted from 1 to 223 via a coaxial network 28; is a monitor television that displays the video signal demodulated by the demodulator 231.

Further, 214 and 215 are each equipped with a television camera of the television conference system, and 224 and 225 are each equipped with a frequency synthesizer, and the video signals from the television cameras 214 and 215 are variably provided with a modulation frequency controlled by the control of the CPU 27. Variable modulator that modulates, 232.23
3 each include a demultiplexer and a variable modulator 225.22.
Demodulators 242 and 243 of the video conference system demodulate the video signals transmitted from 4 through the coaxial network 28, monitor televisions 251 and 252 display the video signals demodulated by the demodulators 232 and 233, respectively. Each,
Microphones 261 and 262 for transmitting speech are speakers for receiving speech.

Next, the operation of the above embodiment will be explained.

In FIG. 1, the CPU 27 includes variable modulators 211 to 2
15 are controlled to be modulated at different frequencies. In this case, if there is no vacant transmission channel, the output of the variable modulator that does not need to transmit the video signal is stopped to prepare a vacant channel.

Therefore, according to the above embodiment, since transmission channels can be dynamically allocated, limited transmission channels can be used effectively, and flexibility is also provided when adding cameras, etc. It is possible to build a highly scalable system.

The LC'PU 27 is also capable of monitoring images from a specific TV camera of the TV system based on operator commands, alarm information from an infrared sensor, and the like.

FIG. 2 shows an ITV system according to another embodiment, in which two demodulators 331% and 332 and a switcher 34 for selectively outputting their output signals to a monitor television 35 are added.

In this embodiment, for example, while the video signal from the camera 31r is input to the monitor television 35 via the variable modulator 321, coaxial network 37, demodulator 3311, and switch 34, the CPU 36 For example, the video signal from the camera 312 is assigned to the variable modulator 322, the coaxial network 37, and the demodulator 3.
32, to control input to the switcher 34;

Then, when the time period for the video signal from the camera 312 to become stable has elapsed, the switcher 34 is controlled so that the video signal from the camera 312 is input to the monitor television 35 .

Therefore, in this embodiment, it is possible to prevent the screen of the monitor television 35 from being disturbed when switching channels in the ITv system.

As described in detail, the present invention provides a plurality of modulators that each modulates a video signal from a television camera at a variable frequency, and the modulator modulates each video signal at a different frequency and sends the modulated signal to a transmission path. This makes it possible to transmit video signals in multiple channels through a single transmission path, and by dynamically allocating channels by changing the modulation frequency, it is possible to create a video transmission device that is flexible and expandable. can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a video transmission device according to the present invention, FIG. 2 is a block diagram showing a second embodiment of the video transmission device according to the invention, and FIG. 3 is a block diagram showing a conventional video transmission device according to the present invention. 1 is a block diagram showing a video transmission device of FIG. 211-215.311-315...TV camera,
22, ~2251.321~325... variable modulator,
231-233.331.332... demodulator, 27.
36...Central processing unit (CPU), 28.37...
Coaxial network (transmission line), 34...Switcher 0

Claims (1)

[Claims] a plurality of television cameras; a plurality of modulators that respectively modulate video signals from the television cameras at variable frequencies;
A video transmission device comprising: a transmission path for transmitting a signal modulated by the modulator; and means for controlling the modulator so that the modulator modulates each signal at a different frequency and sends the modulated signal to the transmission path.