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Aperture which is a kind of optical iris is inside of lens and adjustable. Aperture can control luminous flux of crossing lens. Aperture involves manual aperture and auto aperture: (1) Manual aperture: when brightness changed, it must b
ASF (Advanced Streaming format) is a kind of video compression format used on network. Because of adopting MPEG4 algorithm, compressibility and image quality are relative good. As a video stream format used on net...
Automatic gain control (AGC) is a kind of method for ensuring out-video meet demand of TV transmission provision. Automatic gain control (AGC) controls gain by detecting average PWL (power level) of video signal. Automatic gain control (AGC) can rais
AVI (audio video interleave) is the video format of Windows3.1. Its features include good compatibility, easy adjustment, super image, huge bulk.
AVS is an ENDEC (encoder & decoder) standard of AV (audio & video). AVS standard is created by China. AVS workgroup founded in June of 2002 and held first meeting in August of same year. After 7 normal meetings and 3 video conferences, or abo
Backlight compensation can get ideal exposure of object which is in front of the strong luminance background, no matter object moving to center, top, bottom, left, right or any other position of screen. For a common WDR (wide dynamic range) camera, i
Camera is used for monitoring spot objects. Camera is consisted of CCD sensor (core part), external sync signal circuit, video signal processor and power supply. In recent years, MOS sensor has a great development...
Camera used CCD format can be 2/3", 1/2", 1/3" or others. Image size becomes smaller; accordingly pixel quantity and sensitivity become less. But fortunately this problem has been solved. It is saving-cost for most producers to adopt 1
Content scrambling system is a digital encryption proposal for DVD video. DVD players which are permitted only by CSS can decode video data. Content scrambling system (CSS) is a very effective encryption method, so it is quite popular now. All we kno
DC driver (DD) refers to adding a driving circuit of airs motor within camera. DC driver can directly putout DC controlled voltage to and drive aris motor. Therefore, DC driving camera cost may be higher a little ...
What is depth of field? As some object has clear focal image, there is certain long distant can also be clearly focalized. The distance ranges from front of focal object to back of focal object. This distance is so-called Depth of Field. Depth of fie
Div X refers to digital video CODEC (encoder & decoder) which is based on MPEG-4 skill. Div X format can compress big file into so small file as to can be transmitted on the Internet, thus meeting actual demands of most users.
Bar generator is kind of device generated dot bar video. Bar generator is mainly used for measuring linear and geometric scan distortion of camera and monitor.
Drive pulse refers to sync pulse and blanking pulse.
In CCTV monitoring system, dynamic range means the real illumination scope of camera. At such condition, there are highlights region and shadow region, and all details are clear. The quantity is measured by the vo...
Echo refers to the returned signal from one or more points in signal transmission process. Comparing with original signals, echo signals have obvious difference in amplitude and period. Echo may be previous or lat...
EIA interface refers to a serial standard signal features developed by EIA (Electronic Industries Alliance). EIA interface includes lasting period, waveform, voltage and current.
EIA sync signal refers to the signals ordered to ensure scan synchronous in EIA RS-170 (black and white image) standard, RS-170A (color image) standard, RS-312, RS330, RS-420 as well as continued files....
The accumulating time of electronics of camera can controls exposure time according to the changeability of electronics. This function is called electronic shutter. Electronic shutter function makes camera can capture fast moving targets.
VBR (Variable Bit Rate) means that CODEC (coder-decoder) can auto adjust bandwidth according to data quantity. In other words, when frames change fast and have multi colors, occupation of bandwidth will be larger; otherwise, when frames change slowly
F-number refers to the ratio of focal length (FL) to lens diameter. Fast lens f-number maybe f/1.4, but f/8 refers to very slow speed. The bigger the f-number is, the slower the lens speed is. Lens system: integra...
Fps (frame per second) detection is applied for storing and showing signal quantity of dynamic video. Fps is also a film word or digital video word. As we know, single frame is motionless picture, but continuous displaying frames forms active images
Fresnel lens refers to the lenses incised into narrow ring pattern and polished. There are concentric circle loops or trapezia loops which can centralize all directions light and image them.
Full duplex is defined as sending and receiving synchronic. Full duplex demands: there are specific channels for sending and receiving. Full duplex is applied in star-network and ring-network, even applied to realize communicating between two station
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Half duplex is defined as sending and receiving asynchronous, that is to say first sending or first receiving. Half duplex demands: sending and receiving can use same channel. It is applied in topology and local-area-network (LAN), and applied mostly
2:1 interlace is a term referred in CCTV system. Two fields comprise one frame. For two adjacent fields, lines are scanned alternately with equal interval of time and phase relations.
Lens can be 25.4mm (1 inch), 16.9mm (2/3inch), 12.7mm (1/2inch), 8.47mm (1/3inch) and 6.35mm (1/4inch). Different lenses meet different image dimensions, and we should ensure accordance between image dimension and...
IP protection grade refers to the index for device ability of dustproof and waterproof. This index is mainly used in Europe and Britain goods. IP protection grade is comprised by two digits. The former is the soli...
Isolation amplifier actually is the input circuit and output circuit which are designed especially and avoid affecting each other.
Jitter refers to signal instability caused by mechanical interference, power voltage or components quality change. Signal instability maybe from amplitude or phase position, or from both of them.
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Lag means in TV kinescope, two or more images persistence of vision after removing excitation.
Laser (Light amplification by stimulated emission of radiation) belongs to the optical resonator. There is flat mirror or spherical mirror at two ends, and having optical amplifier in the middle part. Laser sends ...
Leading profile is the main part for pulse rising. Leading profile locates in 10-90% of total amplitude.
As a glossary, line pairs are used to define TV definition. A TV line is composed by one black line and one white line. 525 lines NTSC image involves 485 line pairs.
Load refers to the unit for loading energy putout from equipment.
Loss refers to the reduction of signal PWL or signal intensity. Loss is usually expressed by dB (decibel). Besides, loss means unnecessary power consumption.
Low-frequency distortion refers to the distortion appeared in low-frequency environment. In CCTV monitoring system, it means frequency below15.75KHz.
Low light level/LLL camera refers to the CCTV cameras working wonderfully in night or other low illumination conditions.
Lumen is the expression unit of luminous flux. Lumen equals the luminous flux of candle light shining over a spherical area. As the luminous unit, lumen also equals the surface flux which crosses all points equidi...
NTSC color TV set involves spot illumination or the signals related.
Magnification refers to the measurement discrepancy digits between actual object size and its image size. Usually 1inch lens and 1inch sensor is the reference for focal length (magnification=M=1). 2inches focal le...
Minimum illumination means photosensitivity of CCD or minimum light ray needed by CCD. The illumination unit is Lux. The smaller the number, the less light ray needs for camera, and the more sensible the lens will be. High photosensitivity cameras su
The whole image is divided into multiple areas. Users can choose any one of these areas; even can set sensitivity of chosen area with 1-20 grades. Thus when objects are moving, they can be detected and recorded by camera.
MPEG-4 has much difference with MPEG-1 or MPEG-2. As a compression algorithm, MPEG-4 is also a international standard that meets demands of integration and compression skills such as digital television, interactive graphics application (audio & v
Modern mobile communication and personal communication demand audio function developing to multimedia function. In other word, communication supports audio, word, data, graphics, video and suchlike multimedia, mak...
MPEG image encoding includes three factors: I frame, P frame, B frame. During MPEG encoding process, some images are compressed to I frame, some compressed to P frame, and rest compressed to B frame. I frame compression can reach 6:1 ratio without va
N AVI (new AVI) is created from Microsoft ASF algorithm of compression (no relation with AVI). N AVI improves the insufficiency of ASF format, making N AVI having higher frame rate. Of course it loses ASF streamin...
NTSC / NTSCNTSC (National Television Systems Committee NTSC) is a kind of video standard. NTSC is adopted in America, Canada, Japan, and some middle-south America countries for commercial TV broadcast. NTSC format speed is 30fps (30 Hz) and resolutio
Optical distortion refers to the incorrect image of objects. Distortion involves many types.
PAL (Phase Alteration Line) is I adopted in most Europe countries, Australia and some middle-south America countries for commercial TV broadcast. PAL format speed is 25fps (25 Hz) and resolution is 625 lines (horizontal).
Pixel is the essential parameter for measuring quality of lens. Some packs appear 0.3million or 0.35million. Although the more pixels, the better quality image will be, but not to say the more pixels, the better. For same image, high pixel camera has
QCIF is a popular, standard image formant. H.323 protocol group defines standard capture resolution for video capture device. QCIF = 176×144 pixels
QSIF (Quarter-size Standard Image Format) image has only 25% size of SIF image, BTSC format with 176＊112 pixels; PAL format with 176＊144 pixels. MPEG-1 compression standard supports QSIF image size....
Random interlace is a CCTV system used scanning skill. There-among, two composed fields are non-synchronous. The connected two fields have unstable ties between adjacent lines on time or phase relationship....
Real-time Encoding and Decoding System
Real-time Encoding and Decoding System refers to that camera can real-timely process data, convert into normal MPEG－1or MPEG－2 image, finally store images to HD (hard disk). During this process, data will not be accumulated or lost, which is differen
RealVideo （RA、RAM）format adopts for video streaming since generation, or is considered as the creator of video streaming skill. RealVideo can be continuously played with 56K MODEM dialup. Of course its image qu...
In order to control luminous flux of lens, it is common to add a diaphragm (or called aperture). Assuming d stands for the effective aperture of diaphragm, D stands for actual effective aperture affected by refrac...
Resolution is an important parameter to evaluate cameras. It means that when a camera shoots the bars spaced at equal interval between black and white, the most number of lines could be seen on the screen of monitor (the resolution of the monitor oug
Standard Image Format, NTSC format with 350＊240 pixels; PAL format with 352＊288 pixels. MPEG-1 compression standard supports SIF image size.
Signal-to-Noise Ratio is a main parameter of camera. SNR=signal/noise×20log. Most cameras show the SNR specific-value when AGC shuts. Showing this specific-value is in order to avoid noise PWL (power level) rising accordingly with weak signal r
As the essential operation for image figure, softening can be completed during image capturing process. Softening can remove image blocking effect at object edge to improve intensive low-speed capture after image ...
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Lens has a fixed view. This field angle with fixed height and width is the so called viewing angle. Viewing angle is affected by f (focal length) and target surface size h/v (horizontal size and vertical dimension...
WDR (wide dynamic range) means a kind skill of ensuring camera recognize specific features of objects in strongly contrast. WDR camera is scores of times as dynamic range as traditional camera which has only 3:1 dynamic range. Natural light ray range
For object color changes along with luminance, there are different color-temperatures of images coming from different illumination conditions. For instance, tungsten lamp illumination makes image turn yellowing. Generally speaking, CCD cannot auto-ad
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