What must I know to buy an HD camcorder?

From the point of view of engineering application, and focusing on practicality, how to purchase HD cameras in security monitoring projects is analyzed.

1, understand the demand . HD cameras are mainly used in financial systems, road traffic monitoring and other places where there are special requirements for images. These places all have high demands on the images and can clearly see the features of the faces, license plate numbers, etc. Therefore, if the project you undertake is the application site, you can consider whether to choose the product from the cost.

2, understand the product . At present, the market has positioned cameras with more than 480 lines as high-definition cameras. Actually, some of the high-definition cameras with 500 lines or more sold on the market are basically the same as the 480-line CCDs, which are mainly different from the digital video processing chip (DSP). . Some vendors have strong R&D capabilities. They have developed 15-16 bit (bit) video digital processing chips, which have stronger data processing capabilities and faster image processing than Sony's 10-bit (bit) chips on the market for 480TVL cameras. speed.

3, indicators testing . In fact, the definition of high-definition surveillance cameras and 480 lines above 500 lines is difficult to distinguish from the naked eye alone. Therefore, we must first use professional test equipment to test, test camera resolution, color reproduction, signal to noise ratio, low illumination, synchronization, color synchronization, subcarrier frequency and other technical indicators. Second, you can simulate some scenarios for testing. Mainly to observe the static resolution, dynamic resolution, color reproduction. Can shoot scenery, scenery, flowers, moving objects, people, observe whether the screen is clean, noise size, color is natural and realistic.

4, functional . High-definition surveillance cameras are mainly embodied in the definition of the picture. To achieve the definition of the picture, not only a horizontal resolution of 540TVL, but also some wide dynamic, automatic white balance, sharpness of the image. Adjustments, super digital noise reduction (signal-to-noise ratio), smart digital automatic metering compensation and other functions. When detecting the wide dynamic function, it is necessary to observe whether the transition between the bright area and the dark area is clear and natural, and whether the wide dynamic range can be automatically adjusted. Good cameras have rich levels and delicate performance in bright and dark areas. When looking at license plates under nighttime headlights, the outline of the headlights, filaments, and license plates are all very clear, and no bright lines appear. Low illumination requires observing whether the camera's surveillance picture is clear and how loud the noise is at night.

5, operation settings . The operation setting is mainly examined from the convenience of camera parameter settings. The current HD camera operation settings are mainly adjusted through menus and dialing. Cameras with menus need to pay attention to whether menu functions are rich, easy to adjust, and whether they can meet different complex monitoring environments. The Chinese menu is easier to debug than the English menu. At present, some camera menus include standard daytime, day/night, night KTV entertainment venues, and custom mode. You only need to select one mode to easily cope with various complex environmental needs.

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, pay attention to whether its data interface is rich. Observe whether there is alarm interface, audio interface and RS-485 interface on the rear panel. Some interfaces can improve the security level of monitoring, and some interfaces can facilitate remote menu call settings.

7, a wide range of power supply . In actual projects, the phenomenon of unstable power supply and burning of the camera is often encountered. Especially in some remote mountainous areas, when the voltage is high or low, it is very easy to cause surveillance cameras to fail to operate normally. At present, most of the camera's power supply is AC24V and DC12V. However, some manufacturers' cameras have the power redundancy function. For example, the standard voltage is AC12V, but the camera can work normally between 9 to 16V. The advantage of a wide range of power supply is naturally highlighted when the voltage is unstable.

8, installation and commissioning . The installation and debugging methods of HD video cameras and ordinary video cameras are basically the same, but we must pay attention to the lens selection, because the quality of the lens is not good, or the matching is not good, which will affect the sharpness of the screen to a great extent. For example, the size of the lens, and whether it matches the surveillance camera must be considered. In addition, the back focal plane of the lens must be adjusted. The front glass of the protective cover must be made of good quality optical glass, which will affect the sharpness.

9, supporting products . To obtain high-definition video, in addition to the front-end is a high-definition camera, the transmission system, intermediate system and terminal display system must meet the bandwidth and compression requirements in order to achieve high-definition practical results. Including cables, arrays, hard disk recorders, video servers, various video encoders, etc. Fiber optic cable has large bandwidth, low attenuation, high anti-interference, and can better guarantee the image transmission. The terminal display device preferably selects a progressive scan monitor and is more than 600 lines. Therefore, the use of high-definition cameras and the neglect of the selection of other ancillary equipment cannot achieve the true purpose. 10. Technical support. Finally, before purchasing a product, don’t forget to understand the vendor’s technical support on the product, whether it can provide specific technical training, explain the product’s special features and operation menu in detail, and for the construction of the project, It is the most practical. In addition, if the product fails to work properly, it is also important that the manufacturer can provide corresponding technical services and maintain and repair the product in the shortest time.

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