Choosing a camera video surveillance camera - an image source object selected for monitoring or protection. We all know how much in video surveillance systems depends on the camera, which is a key element of these systems. Correctly chosen camera provides high image quality, and this is the main, though not the only requirement for obtaining the desired image on the screen of the operator security system. The role of video in analog video surveillance systems is obvious and requires no special explanation. But in the digital video surveillance systems and records that are now becoming the dominant role of the camcorder is no less, and perhaps even more important. No, even the most intelligent software can not improve the poor quality of images obtained with false information for the selected operating conditions camcorder. In this case, important information will be lost forever. And if you consider the follow-video compression and a low rate, which provides further information loss and reduced quality (depending on the algorithm and compression ratio), it becomes apparent that professional digital video cameras for surveillance role should not be underestimated in any case. As a rule, when choosing a camcorder specialists in CCTV prefer high quality images; design model (the benefit to choose from) and the minimum set of cameras needed for the task. However, the correct choice of camera does not solve all problems. Do not forget that the improper installation video can be reduced to "no" all the advantages of the model. There are plenty of practical advice (of which will be discussed below) to install video cameras, depending on the specific conditions of the object. But one can say with certainty: the protection of the object - a task for professionals, and it must be solved at the professional level. In the case of the budget deficit this decision can be implemented in several stages, but, nevertheless, its implementation should remain at a high level. Such a solution is possible only if the use of quality equipment. Under the conditions of Russian reality miser pays twice, and at the same time jeopardizing the safety of the object itself, with its complex infrastructure. After a stormy introduction of CCTV in Russia in 1991, there have been many changes. Obsolete video cameras with a resolution of no more than 400 TV lines and a low sensitivity of 1 lux to be replaced by others. They are designed to meet modern ideas about the image quality and are made based on the latest technologies. The last two years have shown significant development opportunities of equipment used in CCTV. Even more rapidly develop new digital technologies for processing, transmission and storage of large volumes of video quality. Therefore, the average image quality and minimum set of video cameras have ceased to hold the experienced user. And the companies supplying equipment to market CCTV, have something to offer them. Currently, the CCTV market a wide range of models in which it is difficult to understand the uninitiated user. Range of tasks that can solve these cameras is very broad. From simple, such as visual observation of the visitors to the complex, such as remote access to cameras of any object through the global Internet. In each case, depending on the task (observation area, protection of territory, the identification of the offending area and further monitoring of the situation with a high degree of informativity), we need to find a compromise between a set of required parameters, the possibility of choosing the model and its price, especially in conditions of limited budget. We will try to acquaint the reader with a modern market of video cameras and their applications. Classification CCTV Based on the requirements of the customer you almost immediately can accurately decide what place the protected area needs to see on the screen. This condition will tell you the type of video camera according to the following classifier. All cameras can be divided into fixed and manageable, which in turn depends on the operating conditions referred to as video cameras and video cameras for indoor outdoor use. Stationary cameras for rooms can be divided into standard (non-embedded lens) are cylindrical and dome, which has already been installed with a fixed aperture lens or a lens with auto iris (auto iris). Both types of cameras are intelligent, integrated and easily manageable. Components of the camera: - payment to the scheme of signal obtained with the installed CCD, a composite video - Lens mount C, CS, M12 - camcorder power supply (internal or external) - Housing (rectangular or dome forms) - Additional built-in or external function modules (transmitters video, lightning protection devices, etc.). The first camera (in the 30's) were fabricated on glass tubes coated with light sensitive phosphor on the inner surface of the glass. They are called the pickup, and they work on the principle, based on the photoelectric effect. When a closed-circuit television, there are two types of tubes: vidicons and nyuvikony. The operation of all transmitting tubes is based on the principle of scanning an electron beam coating inside the tube under the influence of the electromagnetic field. Video cameras based on the tube nyuvikon were more sensitive, expensive and only worked in conjunction with lenses with auto iris. If the analogy to television tubes used in televisions, we can define a number of features that do not exist in the current matrix based on CCD technology - large size cameras, the presence of high-precision, poorly protected from external influence, deflecting system, the need for high voltage, low lifetime of the phosphor coating, the presence of strong geometric distortions. First, micro-electronic technology does not allow a picture element (pixel) charge-coupled devices (CCD) is less than the electron beam obtained in video cameras that are based on tubes. As a result, the resolution cameras, built on the basis of CCD, there was very low. In the 70 years when it was revealed that the charge-coupled devices are very sensitive to light, rapid development of CCD technology. Today it reached a high level. Now we get a matrix that can produce not only very high resolution, but also demonstrate high sensitivity by reducing the losses at the stage of converting light (photons) stream into a standard video signal. In modern conditions the CCD array manufactured by several companies that are leaders and specialize in producing chips for television cameras. Such companies have their own production and research laboratories, small enough - Panasonic, Samsung, Sony, Sharp and others. As a general rule, cameras are based on the matrix produced by these companies, and circuit studs in a position to either keep the parameters of the initial level of the signal obtained by the matrix, or make it worse, very much. Thus, the image quality depends not only on a single CCD, but also on the level of circuitry, the manufacturer sold to end camcorders. Additional deterioration of image quality make the lenses used in the camcorders. In the CCTV lenses are used with fixed and variable focal length (zoom). A detailed description of factors that affect the quality of the optics - very broad question, and its comprehensive coverage is beyond the scope of this article. In this regard, enough to emphasize that the quality of lenses depends on such factors as the type of glass, mechanical components, design, manufacturing technology. All manufactured lenses can be divided by way of aperture control - manual and automatic. In lenses with auto iris control is done automatically: depending on the level of luminous flux, falling on the matrix, changing the relative aperture of the lens through which it passes. Aperture control occurs through the servo amplifier. There is one feature of the construction of the iris lens with auto iris. Lenses with ARD are divided into two subgroups. In the first sub-aperture control by the video signal - VD (video drive), and the second sub-iris control signal DC - DD (direct drive). The difference between the two subgroups is that the lens is related to the second subgroup, semiconductor amplifier elements iris located on-board cameras. This feature of the construction scheme diaphragm imposes certain requirements for compatibility, the lenses and cameras made by different manufacturers. But at the same time, the lenses with iris DC cheaper. Nowadays, when the producers trying to compete in the market, introduce additional features in the video, you can choose any lens aperture control. From a practical standpoint it makes sense to give preference to well-known original equipment manufacturers of this type (depending on the task) - Panasonic, Ernitec, Computar, Canon, Avenir or Tokina. To block your camcorder does not have specific requirements, but if improperly selected, he can influence the output parameters of the camera. For its power use mostly standard (transformer) power supply unit (corresponding to the power consumption of the camcorder) with an input voltage of 220 (24) / 50 Hz and output stabilized voltage 9 V or 12 V (with a ripple of 10 mV). This power supply depending on the model of camera can be remote or built into the camcorder body. Built-in power, of course, the best option in terms of nutrition, because manufactured and tested at the plant, which produces the final assembly. But these cameras are not always convenient to use when it comes to applying another voltage or when solving design problems (lack of visibility of cable lines, stealth installed video cameras, no place for a successful installation, etc.). Then apply power to the remote blocks the elements stabilizing the output voltage. This is a very important thing, which many people forget, because the absence of stabilizing the supply voltage with low ripple (AC component of output voltage with a frequency of 50 Hz) is often a cause for interference in the video signal or an unstable camera. Let me remind you again that the camcorder can be divided into several design types - rectangular, cylindrical and spherical. Rectangular chambers are supplied without a lens, and in spherical and cylindrical lens has a built-in fixed or auto iris, which is a complete solution and simplifies the user experience. Not always sticking out in all directions wires of different colors and eye-catching arm will suit the discerning customer. Believe me, you do not have to blush and make excuses, if you go to these simple questions creatively. General recommendations depending on the operating conditions Lighting Good lighting - an important condition for obtaining high-quality video, especially in color application.
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