Composition of closed-circuit monitoring system in centralized monitoring

The closed-circuit monitoring system is composed of five parts: camera, transmission, control, display and video.

(1) Camera device. This part is the forefront part of the CCTV security monitoring system and the "eye" of the entire system. It is arranged at a certain position of the monitored place, and its field of view can cover the entire monitored place. When the area of ​​the monitored site is large, in order to save the number of cameras, simplify the transmission system and the control and display system, an electric (remote control) variable focal length (zoom) lens is added to the camera to enable the camera to observe The distance is farther and the observation is clearer; sometimes the camera is installed on the motorized gimbal. Through the control of the console, the gimbal can drive the camera to rotate horizontally and vertically, so that the camera can cover a wider angle, The area is larger. In short, the camera is like the eyes of the entire system. It converts the monitored content into an image signal and transmits it to the monitor in the control center.

The camera device mainly includes a camera, a lens, a gimbal, a decoder box, an alarm probe, and an emergency button.

(2) Image transmission. The transmission part is the image signal path of the system. Generally speaking, the transmission part refers to the transmission of image signals. However, because some systems require the transmission of sound signals in addition to images, at the same time. Since the control center needs to control the camera, lens, gimbal, protective cover, etc. through the console, the transmission system also includes the transmission of control signals, so the transmission part here usually refers to the transmission by all The sum of the transmission system formed by the signal.

The transmission medium of the transmission part mainly includes video cables, control signal transmission cables, and optical cables.

At present, the analog signal transmission is mainly used in the computer room, and the coaxial cable is mainly used for the transmission of the TV monitoring signal. The signal generated by the camera is not modulated and is directly transmitted by baseband, so the signal frequency is low and the transmission distance is long. It can transmit 250m with 75-5 cable, which can fully meet the needs of the computer room.

If you use a digital camera, you need to use the local area network to transmit the signal, the transmission line is the twisted pair of the integrated wiring system.

(3) Image control. The control part is the "heart" and "brain" of the entire system, and it is the command center that realizes the functions of the entire system. The control part is mainly composed of the main console (some systems also have auxiliary consoles). Its main function is to remotely control the camera, lens, gimbal, protective cover, etc. to complete the comprehensive and detailed monitoring or tracking monitoring of the monitored place. There is a video recorder on the main console, which can record the situation of the monitored place with images at any time, so that it can be used for future reference or as an important basis.

The main equipment of the control part includes matrix host, multimedia control system, alarm control machine, multi-screen splitter and so on.

(4) Image display device. The display part is generally composed of one or more monitors. Its function is to display the transferred images one by one. In the CCTV security monitoring system, especially in the CCTV security monitoring system composed of multiple cameras, generally not one monitor corresponds to one camera for display, but the image signals of several cameras are monitored by one The device switches the display in turn, so as to save equipment and reduce space occupation.

The main device of the display part is the monitor.

(5) Image recording equipment. Recording is done by VCR or DVR. The recorded information facilitates future verification.

The main technical requirements of the CCTV monitoring system include the definition of the camera, the transmission bandwidth of the system, the signal-to-noise ratio of the video signal, the format of the TV signal, the image quality accuracy and operating functions of the camera, and the environmental adaptability of the system components.