JPH03145238A - Frequency multiplex transmission system and controller therefor - Google Patents

Abstract

PURPOSE:To improve the mount and installation utilization efficiency by operating each terminal equipment according to a command data when an address data of a data block is coincident with its own address and sending the information of its own terminal equipment to a transmission line. CONSTITUTION:Each of terminal equipments E11-Enxn receives a data block sent from a center 2 and uses an address discrimination means 40 to discriminate whether or not specifying its own terminal equipment is included. When the address data is included, a control means 46 adjusts an angle and a focus of a television camera, e.g. 48 according to a command data included in the data block. When a transmission request of information is included in a received command data, a signal modulating a carrier of a channel assigned to a terminal equipment according to an information signal of the terminal equipment outputted by a modulator 49 is sent to a transmission line via a switch means 47. Thus, the mount and installation utilization efficiency is improved.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a system that transmits signals such as video, audio, and monitoring using a frequency-multiplexed multi-channel transmission path, and a control device for the system.

[Prior art]

2. Description of the Related Art Conventionally, there has been a surveillance and security system in which a large number of television cameras are installed at a large number of locations in high-rise buildings, etc., and are monitored all at once by a control center. In this system, video signals captured by each TV camera are transmitted to the center via each signal line, and control signals that control the angle of each TV camera are transmitted to each terminal where the TV camera is installed via each control signal line. It was transmitted up to

[Problem to be solved by the invention]

For this reason, the number of signal lines between the terminal and the center has increased, posing problems in terms of equipment usage and implementation. Another possibility is to assign a unique channel to each television camera and transmit the video signal by frequency multiplexing.
If the number of TV cameras installed is several hundred, it will cost 600M.
A band from Hz to 3000 MHz is required, which is not realistic. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its purpose is to provide a transmission system and a control device thereof that are highly efficient in packaging and equipment utilization.

[Means to solve the problem]

The first invention relates to a transmission system, in which a center and a plurality of terminals are connected by a coaxial cable constituting a frequency-multiplexed multi-channel transmission path, and when the plurality of terminals are classified into a plurality of groups, they belong to the same group. When multiple terminals are assigned to the same channel on a transmission path, each terminal sends its information to the center via the channel assigned to that terminal, and any one channel on the transmission path is used as a control channel. sends a data block consisting of address data that specifies the terminal to which data is to be sent and command data that gives commands to that terminal through its control channel, and each terminal transmits a data block when the address data in the data block matches its own address. , operates according to the command data of the data block, and transmits information of its own terminal to the transmission line according to the command data. Further, a second invention relates to a terminal control device used in the above system, including a modulator that modulates a carrier wave of a terminal-specific channel according to terminal information, and a modulator that is connected to a transmission path and modulates a signal of a specific control channel among the multiple channels. A demodulator that demodulates I! If the address determining means determines whether or not the data block output by the device includes address data that matches the address of the self-terminal, and the address determining means determines that the self-address and the address data match, a control means for controlling the terminal according to command data of a data block output from the demodulator; and a control means disposed between the modulator and the transmission line, the control means for controlling the terminal according to the signal 1 output from the control means; and switch means for connecting or disconnecting between.

[Effect]

Data blocks are transmitted from the center to the terminals using one control channel. Each terminal receives the data block sent from the center via a demodulator,
The address determining means determines whether address data identifying the own terminal is included. When the own address data is included, the control means adjusts the angle and focus of the television camera, for example, in accordance with the command data included in the data block. Additionally, if the received command data includes a request to transmit information, the information signal of the terminal output from the modulator causes a signal modulated on the carrier wave of the channel assigned to the terminal to be transmitted via the switch means. Output to the transmission line. The terminal information is then received at the center. In this way, a frequency-multiplexed multi-channel transmission path is used, and multiple terminal devices are assigned to one channel, but terminal information is transmitted in response to requests from the center. , so there will be no confusion. With such a system, it is possible to connect several times to several tens of times as many terminals as the number of channels on the transmission path.

【Example】

The present invention will be described below based on a specific example. FIG. 1 is a diagram showing the overall configuration of this system. The coaxial cable 1 includes m terminal devices Ell to Enx,
, , the central monitoring device 2 placed at the center, respectively,
It is connected to the branch Bl-wBm via the coupler Bc. Coaxial cable 1 has (n+1) channels cho to ch
n frequency-multiplexed signals can be transmitted. Each channel has 6MI so that television video signals can be transmitted.
(1 channel chO of the n+1> channels is a control channel that transmits operation command data from the central monitoring device 2 to each terminal device,
The other n channels are video channels for transmitting video signals from the terminal device to the central monitoring device 2. A number of terminal devices are assigned to each channel. For example, channel chi has terminal bags [E111 to El
x, but on channel ch2 there are terminal devices [121 to E2
x2 is assigned. Although it is not possible to view the images output from terminal devices assigned to the same channel at the same time, the central monitoring device 2
You can view them in order by scanning them sequentially. Note that a plurality of terminal devices assigned to different channels can be simultaneously monitored by the central monitoring device 2. The central monitoring device 2 has a control panel 23 operated by an operator.
An image controller 24 outputs command data to control each terminal device according to the operating state of the terminal device, and displays an image on the CRT 23 based on the video signal transmitted from each terminal device.
It has a CPU 20 that controls. The control panel 23 is operated by an operator and is used to remotely control each terminal device, including a designated switch for the terminal device desired to receive video signals, a power switch for the TV camera of that terminal device, and a vertical and vertical switch for the TV camera. A horizontal angle adjustment stake, lighting switch, zoom switch, focus adjustment switch, etc. are provided. The operating state of the control panel 23 is read by the CPII 20 via the input/output interface 27. The ROIJ 21 stores the operating program of the CPU 20, and the RAM 22 stores the operating state of the control panel 23 and other control states. A data block having address data and command data for controlling each terminal device is processed by the CPU 20.
It is output to the RF modem 26 via the input/output interface 29. The RF modem 26 modulates the carrier wave of the control channel chO based on the data block, and the modulated signal is output to the control channel cho of the transmission line 1 via the coupler Bc. From each terminal device, video channels ch1 to c of transmission path 1
A video signal is output to hn. The video signal is received by the demodulator 25 of the central monitoring device 2, demodulated for each channel chi to chn, and sent to the image controller 25.
4 is output. The image controller 24 is a CRT 23
to display the video imaged by each terminal device based on the video signal of each channel chi to chn. At this time, the CRT 23 displays the video of the channel specified by the CPII 20. By sequentially switching channels with the CPU 20, the channels displayed on the CRT 23 can be sequentially changed. Also, CPU 2
0 manages which terminal device outputs the video signal even on the same channel, so currently CRT
It is possible to display which terminal device the video displayed at 23 belongs to. Further, under the control of the CPU 20, it is also possible to fix the channel and sequentially change the terminal device that outputs the video signal. Furthermore, the screen of the CRT 23 can be divided to display a plurality of channels at the same time. The configuration of one terminal device is shown as a representative terminal device Bkl connected to channel chk. The control channel chO signal of transmission line 1 is transmitted to RP modem 4.
1 and read by the CPU 40 via the input/output interface 42. That CPII 4
0 stores a ROM 43 that stores an operating program, and a data block input from the PR modem 41.
AM44 is connected. Further, the CPU 40 outputs control signals to the camera control device 46 and analog switch 47 via the input/output interface 45. According to the received command data, the camera control device 46 turns on and off the power switch of the television camera 48, turns on and off the lighting, drives the vertical and horizontal angle adjustment motors, and drives the focus adjustment motor and the zoom motor. do. A video signal output from the television camera 48 is input to a modulator 49. The modulator 49 modulates the carrier wave of channel chk based on the video signal and outputs it to the analog switch 47. Analog switch 49 is normally in a signal passage blocking state. Then, when the central monitoring device 2 requests exit of the video signal from the terminal device, the CPU 40 decodes the command data output from the central monitoring device 2 and sets the terminal device to a signal passing state. As a result, the video signal is output from the terminal device 111kl to the channel chk of the transmission path 1. Next, the processing procedure of the CPU 20 of the central monitoring device 2 will be explained with reference to FIG. In step 100, the status of each switch on the control panel 23 for remotely controlling the terminal device is read. Next, in step 102, address data for specifying the terminal device requesting transmission of the video signal is created from the setting data of the terminal designation switch on the control panel 23. The control panel 23 also controls the on/off status of the power switch of the television camera 48 of the terminal device, the operating status of the vertical and horizontal angle adjustment stakes of the television camera, the on/off status of the lighting switch, the on/off status of the zoom switch, and the on/off status of the focus adjustment switch. Corresponding to the on/off state, the corresponding bit is “1” or “
0" command data is created. Next, by determining whether a CD (carrier detection) signal is output from the RF modem 26, it is determined whether the control channel chO is in an empty state. If it is empty, the process moves to step 106, and a data block consisting of address data and command data is output to the RF modem 26. The RF modem 26 inputs the data block, modulates it, and then sends the data block to the transmission line 10 channel chO. Next, the process moves to step 108, and the address data of the designated terminal device and the channel number data assigned to that terminal device are output to the image controller 24. Based on the data, the image controller 24 selects the video signal of each channel output from the demodulator 25, and displays an image on the CRT 23 based on the video signal of the designated channel. As a result, the image captured by the designated terminal device will be displayed. If the control channel chO is not empty in step 104, the process moves to step 110, waits for a certain period of time, returns to step 100, and repeats the same process. Next, the processing procedure of the CPU 40 of the terminal device Ekl is explained as follows.
This will be explained with reference to the figures. The RF modem 41 encodes the control channel chO signal, and this program encodes the signal from the RP modem 41 to 11'[
) signal is output. In step 200, a data block encoded by the RF modem 41 is input. Next, in step 202, the address data for the data block is decoded. Next, in step 206, it is determined whether the address data matches the address assigned to the own terminal device. If it matches the self address, in step 206,
Command data following the address data is decoded. Then, in step 20B, a command signal for turning on and off the power of the television camera 48, vertical and horizontal angle adjustment of the television camera 48, according to the "1" or "0" state of each bit of the received command data. A command signal for rotating/stopping the camera motor, a command signal for turning on/off the illumination, a command signal for rotating/stopping the zoom motor, and a command signal for rotating/stopping the focus adjustment motor are output to the camera control device 46. The camera control device 46 inputs the command signal and turns on and off the power of the television camera 48.
The vertical and horizontal angle adjustment motors of the television camera 48 are rotated or stopped, the lighting is turned on and off, the zoom motor is rotated or stopped, and the focus adjustment motor is rotated or stopped. Next, the process moves to step 210, and the analog switch 47 is placed in a signal passing state or a signal passing blocking state in accordance with the command data. This terminal device! When a request is made to send a video signal from 1 to 1, the analog switch 47 enters the signal passing state, and the video signal of the television camera 48 modulated by the modulation circuit 49 is output to the transmission line 1 as a signal of channel chk. . As a result, the centralized monitoring device 2 can display images captured by the specified terminal device Ekl, and can monitor the surrounding environment using the terminal device IEkl. Incidentally, in step 204, if the address data of the received data block is not the own address, the program is terminated without performing the following processing. In the above embodiment, a video monitoring system has been described, but it can also be used for monitoring by multiplex transmission of audio from each terminal, multiplex transmission of status data of each terminal, such as a machine tool, etc. Further, the number of terminal devices connected to each channel is not particularly limited.

【Effect of the invention】

The present invention divides a plurality of terminals into a plurality of groups, connects the plurality of terminals belonging to the same group to the same channel of a transmission path, and transmits information from each terminal to a center using the channel to which the terminal is connected. A data block is transmitted from the center, which uses any one channel of the transmission path as a control channel, and consists of address data that specifies the destination terminal of the data and command data that gives commands to that terminal. When the address data of a data block matches its own address, each terminal operates according to the command data of that data block and sends its own terminal information to the transmission path according to the command data, so the channel More than one terminal device can be connected to the coaxial transmission line, there is no need to increase the bandwidth of the transmission line more than necessary, and the transmission device is easy to manufacture. Furthermore, since the signals that control each terminal are transmitted through coaxial cables, less mounting space is required, and equipment utilization efficiency is improved. Another invention provides a demodulator that demodulates a control channel signal, an address determining means that determines whether a data block output from the demodulator includes address data that matches the address of its own terminal, and a demodulator that demodulates a control channel signal. and the address data match, a control means for controlling the terminal according to the command data of the data block output from the demodulator, and a control means disposed between the modulator and the transmission line, which controls the signal output from the control means. Accordingly, a switch means for connecting or disconnecting the modulator and the transmission line is provided, so that the channel can be shared by a plurality of terminal devices without interference under the control of the center. Therefore, by providing this device in a terminal, it is possible to construct a monitoring system with a high facility utilization rate in which terminal devices are connected more than the number of channels.

[Brief explanation of the drawing]

FIG. 1 shows an entire system according to a specific embodiment of the present invention,
A block diagram showing the configuration of a central monitoring device and a terminal device,
FIG. 2 is a flowchart showing the processing procedure of the CPU of the central monitoring device in the same embodiment, and FIG. 3 is a flowchart showing the processing procedure of the CPU of the terminal device of the same embodiment. l゛・Transmission path 2・Central monitoring device Ell ~ Enxfi - Terminal device 47 - Analog switch

Claims (2)

[Claims] (1) The center and multiple terminals are connected by a coaxial cable, and the coaxial cable constitutes a frequency-multiplexed multi-channel transmission path, and multiple terminals are divided into multiple groups, and multiple terminals belonging to the same group are terminals are connected to the same channel on the transmission path, each terminal sends its information to the center using the channel to which it is connected, any one channel on the transmission path is used as a control channel, and the center sends its information to the center using the channel to which it is connected. A data block consisting of address data that specifies the terminal to which data is to be sent and command data that gives commands to that terminal is sent via the control channel, and each terminal transmits the data block when the address data in the data block matches its own address. A frequency multiplexing transmission system that operates according to command data in a data block and transmits information from its own terminal to a transmission path according to the command data. (2) A terminal control device connected to a frequency multiplexed multi-channel transmission line, comprising: a modulator that modulates a carrier wave of a terminal-specific channel according to terminal information; a demodulator that demodulates a signal of a specific control channel and outputs it as a data block; an address determining means that determines whether the data block output from the demodulator includes address data that matches the address of its own terminal; control means for controlling a terminal according to command data of a data block output from the demodulator when the address determination means determines that the self address and address data match; the modulator and the transmission line; A terminal control device for a frequency multiplexing transmission system, comprising a switch means disposed between the modulator and the transmission path, the switch means being arranged between the modulator and the transmission path according to a signal output from the control means.