Analysis of main components of video surveillance products

The video surveillance system mainly consists of four main components: camera part, transmission part, control part, and display part. The front-end camera section and the back-end control section are the two most important system components.

The camera part of the camera is the front part of the video surveillance system and is the "eye" of the entire system. It is arranged at a location on the site to be monitored so that its field of view covers the entire monitored area. In some cases, the area to be monitored has a large area. In order to save the number of cameras and simplify the transmission system and control and display system, an electric (remote control) zoom (zoom) lens is mounted on the camera to enable the camera to The observation distance is farther and clearer; sometimes the camera is mounted on the electric head, and through the control of the console, the head can drive the camera to rotate horizontally and vertically, so that the camera can cover the angle and area. Big. In short, the camera, like the eyes of the entire system, turns its surveillance content into an image signal and transmits it to the monitor on the control center. Because the camera part is the front end of the system, and the situation in the monitored location is that it becomes an image signal transmitted to the monitor of the control center, the camera part is the original signal source of the system from the whole system. Therefore, the quality of the camera system and the quality of the image signal it generates will affect the quality of the entire system. From the perspective of system noise calculation theory, the biggest factor affecting the system noise is the signal-to-noise ratio of the signal in the first stage of the system (in this case, the camera's image signal output). Therefore, it is important to carefully select and handle the camera section. If the image signal output by the camera reaches the monitor after passing through the transmission section and the control section, the signal to noise ratio of the image signal arriving at the monitor will decrease. This is due to the introduction of lines, amplifiers, switches, etc. in the transmission and control section. The reason for the noise.

In addition to the above discussion, for the camera part, in some cases, especially in the case of outdoor applications, in order to prevent dust, rain, high and low temperature, corrosion resistance, etc., the camera and its lens Special protective covers should be added, and even the PTZ should have corresponding protective measures.

The camera of the camera is a front-end device that acquires the image of the surveillance site. It uses the area-array CCD image sensor as a core component, plus a synchronization signal generation circuit, a video signal processing circuit, and a power supply. In recent years, new low-cost MOS image sensors have developed rapidly. Cameras based on MOS image sensors have begun to be applied to videophones or conference television systems that do not require high image quality. Since the MOS image sensor's resolution and low illumination are not comparable to the CCD image sensor until the main indicator is temporarily used, the camera is still a CCD camera in the television monitoring system.

The camera has the advantages of black and white and color. Since the black and white camera has the advantages of high resolution and low illumination, in particular, it can be imaged under infrared light, so in the television monitoring system, the black and white CCD camera still has a high market share. Incidentally, the cameras in the list of CCTV surveillance equipment listed by each merchant are usually without a lens (except integrated cameras). Therefore, in practical applications, the cameras should be based on the actual environment of the surveillance site and the user's requirements. With the appropriate lens.

The lens lens is an indispensable component in the television monitoring system. The lens and the CCD camera cooperate to image the long distance target on the CCD target surface of the camera.

A wide variety of lenses, from the focal length classification, can be divided into short focal length, medium focal length, and focal length and zoom lens; from the size of the field of view can be divided into wide-angle, standard, telephoto lens; from structural classification, also Can be divided into fixed aperture fixed-focus lens, manual aperture fixed-focus lens, automatic aperture fixed-focus lens, manual zoom lens, automatic iris motorized zoom lens, electric three variable lens (finger, focal length, focus all three are variable) Etc. Because the lens selection is appropriate or not, it is directly related to the quality of the camera. Therefore, a lens must be reasonably selected in practical applications.