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Surveillance camera buying skills

Author:　ComeFrom:　Date:2020-12-8 19:54:44　Hits:1003
economy
At present, the homogeneity of security products is very serious, and the imported ones are almost the same as the domestic ones, so friends, don't blindly worship foreign brands.
2. Stability
Everyone must believe that the best after-sales service is no after-sales service, but there is no after-sales service. Everyone has minor illnesses and disasters, and problems with any product are inevitable.
3. Scientific
The monitoring system is actually more important than the design scheme of the equipment. The same product, in the hands of different engineers, will achieve different effects, which is by no means alarmist.
Fourth, the price should be moderate
Some people want to buy low-priced products and try their best to lower the price. In the end, the seller basically has no profit at all. How can they provide you with high-quality service?
Buy 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. Some manufacturers have strong research and development capabilities. They have developed 15-16-bit (bit) video digital processing chips, which have stronger data processing capabilities and faster images than SONY 10-bit (bit) chips of 480TVL cameras on the market. processing speed.
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. However, the cameras of some manufacturers have power redundancy functions. For example, the standard voltage is AC12V, but the cameras can work normally between 9 and 16V. 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.
Selection guide
The TV surveillance system can directly watch everything that happens in the monitored place and target on the monitor through remote control of cameras, lenses, electric PTZ and other equipment. And it can transfer the image information content of the monitored place and target through the video recorder for recording.
The camera should choose CCD black and white, color camera. The horizontal resolution of black and white cameras is ≥400 lines, and the horizontal resolution of color cameras is ≥270 lines. The signal-to-noise ratio is required to be ≥46dB. Cameras with different sensitivities should be selected according to the illuminance of the surveillance target. The minimum ambient illuminance of the surveillance target should be 10 times higher than the minimum illuminance of the camera. When remote control is required, a remote control lens device with optical focus, aperture opening, and zoom distance can be selected. The camera can choose a charge-coupled device (CCD) type camera that is small in size, light in weight, and convenient for on-site installation and maintenance. The corresponding camera protective cover should be selected according to the working environment. The protective cover can be equipped with a temperature control system and remote wipers as required. A support device for fixing the camera on a specific part, a camera bracket or a pan/tilt can be used. When a camera needs to monitor multiple scenes in different directions, it should be equipped with an automatic focusing device and a remote control electric pan/tilt. When the camera needs to be concealed, it can be installed in the ceiling or wall, and the lens can be a pinhole or prism lens. For the anti-theft system, additional external sensors can be installed in combination with the system for linkage alarm. The system equipment for monitoring underwater targets should use high-sensitivity camera tubes, airtight pressure-resistant, waterproof protective covers, and water seepage alarm devices. The location, direction and lighting conditions of the camera should meet the following requirements:
1) The camera should be installed in a place near the monitoring target that is not easily damaged by the outside world, and the installation location should not affect the operation of on-site equipment and the normal activities of personnel. The installation height should be 2.5 to 5m from the ground indoors; 3.5 to 10m from the ground outdoors, and not lower than 3.5m.
2) The camera in the elevator car should be installed on the top of the elevator car, at the opposite corner of the elevator operator, and should be able to monitor the panoramic view inside the elevator car.
3) The camera lens should avoid direct sunlight to ensure that the target surface of the camera tube is not damaged. In the field of view of the lens, there must be no objects that obstruct the surveillance target.
4) The camera lens should be aimed at the monitoring target from the direction of the light source, and should avoid backlight installation; when backlight installation is required, the contrast of the monitoring area should be reduced.
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