IP camera branches:bolt features and optional

 

Bolt basic functional anatomy

 

    In recent years, with the extensive application security surveillance cameras, Box Camera HD imaging technology, high-Refreshing mist function, infrared detection locked day and night to convert infrared camera function has been widely used in television monitoring project. Gun Camera Day and night infrared camera feature allows the camera to detect infrared filter switch day and night mode, to solve ordinary day and night camera appears frequently day and night conversion issues. Can effectively reduce the image noise in low light conditions at night, to improve the picture quality. Bolt basic functional anatomy

    1. the number of pixels

    Pixel number refers to the number of pixels is the maximum number of pixels of the CCD sensor of the gun-type camera, and some give a horizontal and vertical direction, such as 500H × 582V, some given waiting multiplied value of the two previous ones, such as 30 million pixels. The CCD chip of a certain size, the more the number of pixels means that the area of ​​each pixel cell is smaller, and thus the higher the resolution of a gun type of the camera by the chip.

    2. Resolution

    Resolution is an important parameter to measure of the merits of black-and-white gun type camera, refers to when the gun-type camera pickup arranged at intervals, such as black and white stripes, should be higher than the resolution of the camera on the monitor (high) can be seen on the maximum line number, when more than this number of lines on the screen can only see the gray one can no longer distinguish between black and white lines.

    The test of the resolution is usually to shoot a gun camera resolution test card, and a waveform monitor to read data. Specific methods are as follows:

    (1) are arranged the test environment. Resolution test card on the standard test light box, away from the cameras about 3m far. Gun Camera video the output termination waveform monitor and waveform monitor output is connected to high-resolution black-and-white monitor.

    (2) scene illumination setting for 2000lx, and the color temperature of the light source is set to 3200K.

    (3) adjusting the focal length of the lens to move the camera (or optional suitable fixed focus lens and a little before and after) resolution card image to fill the monitor screen and focus clearest image through accurate.

    (4) observe the resolution of cards selected line oscilloscope waveform.

    (5) Adjust the lens aperture white signal level reached 100% (70mV), then the modulation depth of more than 5% of the number of TV lines is the limiting resolution.

    3. Minimum illumination

    Minimum illumination is an important parameter to measure Gun Camera pros and cons, and sometimes referred to as "illumination" dispense with the word "minimum". Most illumination is the luminance value to a predetermined value when the brightness of the scene subject to a certain extent leaving the gun-type camera output video signal level is low when the light of the scene. Determination of this parameter should be specifically noted the maximum relative aperture of the lens. For example, using the F1.2 lens to 0.04LX when the subject scene brightness value is low, the Monitor Camera output amplitude of the video signal is 50% of the maximum amplitude, i.e. reached 350mV (standard video signal is the most substantial value 700mV), claimed the Gun Camera Minimum illumination 0.04LUX/F1.2. Subject scene brightness value low gun-type video camera output signal amplitude is less than 350mV, reflect on the monitor screen, a screen is difficult to distinguish between the levels of gray images. Currently, the norms of the market is not yet uniform the low illumination characteristics of the gun camera of some low illumination indicators may not as good as the illumination indicators slightly higher low-light characteristics of some gun camera. The reason for this is the standard used in the determination of low-light indicators. Still the foregoing examples, for example, if the video camera output signal amplitude is reduced to 30% of the maximum amplitude (i.e. 210mV) measured for the baseline, were the brightness value of the imaging object can also then low, such as 0.03 lx If further for F1.0 lens of the optical lens, because the light flux increases, the brightness value of the subject scene can also be further reduced, such as 0.02LX.

    The above analysis shows, aside determination of standard and simply to a brand gun camera illumination nominal value and another brand gun camera illumination nominal value to compare not accurately predict which cameras low light characteristics good conclusion, because they are used for the relative aperture of the lens and the output video signal of the predetermined value may not be the same. Therefore, the minimum illumination indicator can only be used for the reference design and optional equipment.

    4. SNR

    One of the main parameters of the signal-to-noise ratio is also a gun-type camera. When the the Gun Camera intake bright scenes, the monitor display screen is usually relatively crisp, the observer is not easy to see the screen interference noise; When the camera darker scenes intake, the monitor display screen is relatively dim, observation by this time it is easy to see the the snowflake interference noise in the picture. Interfere with the strength of the noise of the (i.e., interfere with the degree of influence of noise on the screen) to have a direct relationship with the indicators of good or bad of the gun-type camera signal-to-noise ratio, i.e. the higher the gun type of the camera-to-noise ratio, the interference impact of the noise on the screen more small.

    The bolt the purchase reference

    The so-called "SNR" refers to the ratio of the signal voltage for the noise voltage is usually expressed with the symbol S / N. Under normal circumstances, the signal voltage is much higher than the noise voltage, the ratio is very large, therefore, the actual calculation of the size of the SNR of the camera are usually the ratio of the mean square signal voltage with the mean square noise voltage is taken to the base 10 on The number and then multiplied by the factor 20, i.e. formula (2-3), the unit is expressed in dB.

    The SNR value is given by the general gun-type camera is, because when the AGC ON, interested smaller signals to be improved, so that the noise level is also a corresponding increase in the AGC (Automatic Gain Control) is closed the value of. The typical values ​​generally gun-type CCD camera signal-to-noise ratio is 45dB ~ 55dB. Measuring the signal-to-noise ratio parameter should be used when the video noise measuring instrument to be connected directly to the video output terminal on the gun-type camera.

    The bolt the purchase reference

    Gun Camera is a very wide range of applications, depending on the optional lens, you can achieve remote monitoring or wide-angle monitoring, application occasions hemisphere wide gun-type camera zoom range depending on the lens selected, from the times ranging to a few times, and relatively easy to replace the lens In addition, if demand bolt require additional configuration shields.
1, according to the installation site selection. Ordinary gun-type cameras, both wall mounted can be ceiling mounted, indoor and outdoor unrestricted, more flexible.

    2, according to the ambient light selection. If the lighting conditions are not ideal, should try to use low illumination camera bottom illumination as color surveillance camera, color black-and-white automatically converted to dual-use camera, low-light black and white camera, in order to achieve better acquisition. It should be noted that if the light intensity is not high, and the users of the monitor image clarity requirements, should use a black and white camera. If you do not have any light, it is necessary to add infrared lamps provide lighting or optional infrared night vision function security surveillance camera, which is characterized by: the camera itself has the color black and white conversion mode, and comes with lens and mounting bracket, a unique vacuum packaging design, indoor use without installation of shields, and beautiful appearance, good for hiding, and excellent value for money.

    3, according to the installation method selection. As fixed installation, the camera is more than use an ordinary gun-type camera. The ordinary gun style camera reprovision motorized zoom lens, but the price is relatively high, installed and integrated camera not easy.

    4, according to the requirements on the image definition to select. If the resolution of the image quality requirements, should be used in TV lines indicators cameras. In general, color camera, 420, 520 TVL (TV lines) for parsing camera 480TVL more for the high-resolution camera. The higher the resolution, the price is relatively higher.

    5, should also be noted that some of the performance indicators in the product description. Such as signal-to-noise ratio, auto iris lens drive way. SNR indicators to choose a general television monitoring system is greater than 48dB, so that not only meet the industry standard of not less than 38dB, and more importantly, when the environmental illuminance is low, the higher the SNR of the camera images clearer. The drive way of the lens is generally used in a dual-drive for random selection of DC drive or Video drive auto iris lens.

    6, In addition, selected a video surveillance camera, installed more cautious. Correct operation, such as operating temperature, supply voltage, in strict accordance with product instructions. The vast majority of camera manufacturers temperature indicator is -10 ~ +50 ℃, such as temperature, humidity changes the larger should add special protection. Domestic camera adaptation to an AC voltage is generally in the range of 200 ~ 240V, weak against supply voltage variation, used in the system is required to add the power supply.