Surveillance camera purchase must know

From the perspective of engineering application, and focusing on practicality, this paper analyzes how to purchase high-definition cameras in security monitoring projects.

1. Understand the needs

High-definition cameras are mainly used in financial systems, road traffic monitoring and other places with special requirements for images. These places have high requirements for images, and can clearly see facial features, license plate numbers, etc. Therefore, if the projects you undertake are these application places, you can consider whether to choose this product in terms of cost.

2. Understand the product

In the market, cameras with lines higher than 480 are positioned as high-definition cameras. In fact, some of the high-definition cameras with more than 500 lines sold on the market are basically the same as CCDs with 480 lines, mainly because the video digital processing chip (DSP) is different.

3. Indicator detection

In fact, high-definition surveillance cameras with more than 500 lines and the clarity of 480 lines are difficult to distinguish from the naked eye. Therefore, first of all, professional testing instruments should be used to test the technical indicators of the camera, such as clarity, color reproduction, signal-to-noise ratio, low illumination, synchronization, color burst, and sub-carrier frequency. Second, some scenarios can be simulated for testing. Mainly observe static sharpness, dynamic sharpness, and color reproduction. You can shoot scenery, scenery, flowers, moving objects, people, and observe whether the picture is clean, the noise level, and whether the color is natural and realistic.

4. Functionality

High-definition surveillance cameras are mainly reflected in the clarity of the picture. To achieve the clarity of the picture, not only a horizontal resolution of 540TVL is enough, but also some wide dynamic, automatic white balance, and image sharpness. Adjustment, super digital noise reduction (signal-to-noise ratio), intelligent digital automatic metering compensation and other functions. When testing the WDR function, it is necessary to observe whether the transition between the bright area and the dark area is clear and natural, and whether the WDR can be automatically adjusted. A good camera will have rich layers and delicate performance in bright and dark areas. When looking at the license plate under the headlights at night, the outline of the headlight, the filament and the license plate are very clear, and no vertical bright lines appear. For low illumination, it is necessary to observe whether the monitoring picture of the camera is clear and the noise level at night.

5. Operation settings

The operation setting is mainly examined from the convenience of camera parameter setting. The operation settings of the HD camera are mainly adjusted through the menu and dialing. Cameras with menus need to pay attention to whether the menu functions are rich, whether it is easy to adjust, and whether it can meet different complex monitoring environments. The Chinese menu is more intuitive and easier to use than the English menu. Some camera menus have standard daytime, daytime, nighttime KTV entertainment venues, and custom modes. You only need to select a mode to easily meet the needs of various complex environments, which is fast and convenient.

6. Data interface

In practical applications, surveillance cameras may not work properly due to environmental or human damage. Therefore, when purchasing a high-definition camera, you should also pay attention to whether its data interface is rich. Observe whether there are alarm ports, audio ports and RS-485 ports on the rear panel. Some interfaces can improve the security level of monitoring, and some interfaces can facilitate remote menu call settings.

7. Wide power supply range

In practical projects, the phenomenon that the power supply is unstable and the camera is burned out is often encountered. Especially in some remote mountainous areas, the voltage is high and low, which is very easy to cause the surveillance camera to fail to operate normally. Most of the camera's power supply is AC24V and DC12V. The advantage of a wide power supply range is naturally prominent when the voltage is unstable.

8. Installation and debugging

The installation and debugging methods of high-definition cameras and ordinary cameras are basically the same, but you must pay attention to the selection of lenses, because the quality of the lenses is not good, or the selection is not good, which will greatly affect the clarity of the picture. For example, the size of the lens must be considered whether it matches the surveillance camera. In addition, the back focal plane of the lens should be adjusted, and the front glass of the protective cover should be made of high-quality optical glass, which will affect the clarity.

9. Ancillary products

To obtain high-definition images, in addition to the front-end high-definition camera, the transmission system, intermediate system and terminal display system must meet the requirements of bandwidth and compression, in order to achieve the actual effect of high-definition. Including cables, matrixes, hard disk recorders, video servers, various video encoders, etc. The optical cable has large bandwidth, low attenuation, high anti-interference, and can better ensure various indicators of image transmission. The terminal display device is best to choose a progressive scan monitor, and it is more than 600 lines. Therefore, just using high-definition cameras and ignoring the selection of other supporting equipment will not achieve the real purpose.

10. Technical support

Finally, before purchasing a product, don't forget to know the manufacturer's technical support on the product, whether it can provide special technical training, and give a detailed explanation of the product's special functions and operation menus. These are important for engineering construction. are the most practical. In addition, if the product fails to work properly, it is also very important whether the manufacturer can provide corresponding technical services to maintain and repair the product in the shortest possible time.