Knowledge Base & How-to’s
Glossary of CCTV Terms
automatic gain control: the electronics that regulate the gain or amplification of the videosignal.
the size of the opening in the iris, which controls the amount of light that reaches the ccd sensor. the larger the f-stop numbers, the less light reaches the sensor.
a technique of boosting the video signal level to produce a full amplitude video signal, even when the scene contrast is less than full range (glare, fog, mist, etc.). the darkest part of the signal is set to black and the lightest part to white, thus increasing the contrast.
fully integrated, high speed, pan/tilt/zoom camera built into a protective dome housing allowing full and continuous 360° coverage of the scene.
买哪种彩票中奖率最高the lens continuously adjusts to the correct focus automatically for the sharpest picture.
the lens iris opening is automatically adjusted to allow the correct illumination of the camera sensor.
the camera pans continuously between right and left limit settings.
this function records the sequence of movements of the camera’s ptz for later playback allowing a set pattern to be repeated automatically. this function is often called guard tour.
买哪种彩票中奖率最高as the camera zooms in to increase the size of objects on the monitor screen, the pan and tilt speeds are reduced so that the relative speed on the screen remains constant for similar joystick control positions.
买哪种彩票中奖率最高a patented technology that integrates motion detection into the camera allowing tracking of an object and zooming in to optimize size and perspective.
auto white balance: a feature that allows a color camera to automatically adjust its output color to give a natural color, independent of the lighting used.
short for balance/unbalanced. a device that converts a balanced video signal (e.g. as used on twisted pair) line to an unbalanced signal (e.g. as used on coax). in a balanced line both wires are electrically equal. in an unbalanced line one wire has different electrical properties than the other.
unit of measure for the speed of data transmission.
买哪种彩票中奖率最高bits per second, the actual data rate.
back light compensation: selectively amplifies parts of the image to compensate for large contrast differences when only a portion of the image is brightly lit (e.g. a person in a sunlit doorway).
application and bandwidth rating system for utp cabling. categories 1 through 7 are based on eia/tia-568-b standards. category is typically abbreviated cat. utp category 5, 5e, 6, and 7 are used for ethernet data cabling applications. ethernet wiring distances are limited to a maximum of 100 m (328 ft.) when using utp wiring.
a technology that prevents image degradation caused by signal losses when transmitting video over long cable lengths.
买哪种彩票中奖率最高charged coupled device: a type of solid state image sensor used in cctv cameras. the sensor converts light energy into electrical signals.
买哪种彩票中奖率最高indicates the size of the camera sensor used. in general, the larger the sensor, the more sensitive the camera and the better the image quality. the format is quoted in inches, for example 1/4 or 1/3 inch.
买哪种彩票中奖率最高closed circuit television: a video system that transmits television signals over a closed (non-broadcast) system.
common intermediate format: video format with 352 × 288/240 pixels.
买哪种彩票中奖率最高composite video blanking and sync: the format of an analog television (picture only) signal before it is combined with a sound signal and modulated onto an rf carrier. composite video is often designated by the cvbs acronym, meaning any of color, video, blank, and sync, composite video baseband signal, composite video burst signal, or composite video with burst and sync. it is usually in a standard format such as ntsc, pal, or secam.
Day/Night (IR sensitive)
买哪种彩票中奖率最高a camera that has normal color operation in situations where there is sufficient illumination (day conditions), but where the sensitivity can be increased when there is little light available (night conditions). this is achieved by removing the infrared cut filter required for good color rendition. the sensitivity can be further enhanced by integrating a number of frames to improve the signal-to-noise ratio of the camera.
a feature allowing the shutter speed to be set to a fast speed to eliminate motion blur and provide a detailed and clear image of fast-moving objects while there is sufficient light. when light levels fall and other adjustments have been exhausted, the shutter speed reverts to the standard setting to maintain sensitivity.
买哪种彩票中奖率最高dynamic host configuration protocol: uses an appropriate server to enable dynamic assignment of an ip address and other configuration parameters to computers on a network (internet or lan).
Digital Image Stabilization
see image stabilization
dynamic noise reduction: a digital video processing technique that measures the noise (image artifacts) in the picture and automatically reduces it.
domain name system: a service that stores domain names and translates them into internet protocol (ip) addresses.
买哪种彩票中奖率最高the most commonly used local area network (lan) access method. ethernet complies with the ieee 802.3 standard. the ethernet standard supports 10 mbps, 100 mbps, 1000 mbps, and 10 gb (gigabit) data transmission rates.
Fiber Optic Transmission
refers to the transmission of video and data via optical fibers. optical fibers are thin glass strands that are designed for light wave transmission. video and data are digitized and transformed into a series of light pulses. there are two primary types of optical fiber; singlemode and multimode. singlemode fiber is used when large distances must be spanned, typically greater than 2 km/1.2 miles (see singlemode). multimode is typically used to span smaller distances such as the inside of buildings or on small campuses (see multimode).
Field of View
the measure of the visible area within the camera’s field of view. the larger the focal length, the smaller the field of view. the smaller the focal length, the wider the field of view.
the distance from the optical center of the lens to the image of an object located at an infinite distance from the lens. long focal lengths give a small field of view (e.g. telephoto effect), while short focal lengths give a wide angle view.
买哪种彩票中奖率最高file transfer protocol: used to transfer files between computers on a network, such as the internet.
duplex simultaneous data transmission in both directions (sending and receiving); (see duplex).
a single video image.
买哪种彩票中奖率最高a node on a network that serves as an entrance to another network.
hypertext transfer protocol: protocol for transmitting data over a network.
hypertext transfer protocol secure: encrypts and authenticates communication between web server and browser.
the ability to simultaneously stream ip video across a local or wide area network, and cvbs video via coaxial or fiber optic cabling.
institute of electrical and electronics engineers: the world's leading professional association for the advancement of technology.
the ieee 802.1x standard provides a general method for authentication and authorization in ieee-802 networks. authentication is carried out via the authenticator, which checks the transmitted authentication information using an authentication server (see radius server) and approves or denies access to the offered services (lan, vlan, or wlan) accordingly.
an algorithm that virtually eliminates camera shake in both the vertical and horizontal axes, resulting in exceptional image clarity.
electromagnetic radiation (light) with a longer wavelength than is visible to the human eye. ir illumination is prominent at dusk and dawn and in incandescent lamps. ir illuminators come in the form of lamps with the appropriate filters, leds, or lasers. ccd sensors are less sensitive to ir than visible light, but ir can significantly increase the total illumination level, leading to a much better image at low light levels.
internet protocol: the main protocol used on the internet, normally in conjunction with tcp (transfer control protocol); (see tcp/ip).
ip code (ingress protection) that indicates the degree of protection provided by enclosures for electrical equipment. the first number indicates protection of internal equipment against the ingress of solid foreign objects. the second number indicates protection of internal equipment against harmful ingress of water. higher digits refer to higher levels of protection. see also nema rating.
the address of a device attached to an ip network. each device on an ip network must use a unique address. every ip data packet contains a source address (sender) and a destination address (recipient). each ip address consists of 32-bits that are arranged into four 8-bit octets (x.x.x.x). ip addresses range from 0.0.0.0 to 255.255.255.255.
images per second: a measurement of the rate that pictures are displayed to create a video stream. a rate of 25 ips (pal) or 30 ips (ntsc) is generally considered to be full motion video.
integrated services digital network: comprised of digital telephony and data-transport services offered by regional telephone carriers. isdn involves the digitization of the telephone network, which permits voice, data, text, graphics, music, video, and other source material to be transmitted over existing telephone wires.
joint photographic experts group: the name of the committee that created a standard for encoding still images.
买哪种彩票中奖率最高kilobits per second: the actual data rate.
local area network: a communications network serving users within a limited geographical area, such as a building or a university campus. it is controlled by a network operating system and uses a transfer protocol.
买哪种彩票中奖率最高the international system unit (see si) of measurement of the intensity of light. it is equal to the illumination of a surface one meter away from a single candle.
买哪种彩票中奖率最高media access control: a quasi-unique identifier attached to most network adapters (nics). it is a number that acts like a name for a particular network adapter.
买哪种彩票中奖率最高motion jpeg is a digital video encoding standard where each video frame is separately compressed into a jpeg image.
买哪种彩票中奖率最高a further development of mpeg-2 designed for transmitting audiovisual data at very low transfer rates (for example over the internet). a digital video encoding and compression standard that uses interframe encoding to significantly reduce the size of the video stream being transmitted. with interframe coding, a video sequence is made up of keyframes that contain the entire image. in between the keyframes are delta frames, which are encoded with only the incremental differences. this often provides substantial compression because in many motion sequences, only a small percentage of the pixels are actually different from one frame to another.
a convention or standard that controls or enables the connection, communication, and data transfer between two devices. in ptz cameras, such as the autodome and pan/tilt units, protocol refers to the standard used to control the pan, tilt, and zoom (ptz) operation of the camera. since each camera manufacturer’s ptz protocols are unique, multi-protocol support is needed to support third party systems. autodome cameras support the pelco d and p protocols as well as advik’s own biphase protocol (see biphase). the pan/tilt units support the pelco “d” protocol as well as advik’s own biphase and bilinx protocols (see bilinx).
electrical standards and publications published by nema (national electrical manufacturers association). specification standards in reference to the operating environment for a variety of electrical devices.
a mask that explains which part of an ip address is the network address and which part is the host address. it is usually written in dotted decimal notation, for example 255.255.255.192 (see also subnet mask).
a method of boosting the sensitivity of high-resolution advik color cameras by 9 db (a factor of 3) by combining the signal of the color image in a single monochrome picture.
on-screen display: menus are shown on the display monitor.
买哪种彩票中奖率最高camera movement in the horizontal direction.
values used for configuration.
the smallest addressable unit on a display screen or bitmapped image.
1) on computer and telecommunication devices, a port (noun) is generally a specific place for being physically connected to some other device, usually with a socket and plug of some kind. typically, a personal computer is provided with one or more serial ports and usually one parallel port.
2) in programming, a port (noun) is a logical connection place and specifically, using the internet protocol tcp/ip, the way a client program specifies a particular server program on a computer in a network. higher-level applications that use tcp/ip, such as the web protocol hypertext transfer protocol, have ports with preassigned numbers. these are known as well-known ports that have been assigned by the internet assigned numbers authority (iana). other application processes are given port numbers dynamically for each connection. when a service (server program) initially is started, it is said to bind to its designated port number. as any client program wants to use that server, it also must request to bind to the designated port number. port numbers are from 0 to 65535. ports 0 to 1024 are reserved for use by certain privileged services. for the http service, port 80 is defined as a default and it does not have to be specified in the uniform resource locator (url).
a pre-selected and stored combination of pan, tilt, and zoom positions that allow a set view to be recalled. also known as preset shot.
买哪种彩票中奖率最高a sequence of preset shots combined to provide a pre-programmed tour of the area covered by a programmable camera.
买哪种彩票中奖率最高the ability to mask out a specific area to prevent it from being viewed.
买哪种彩票中奖率最高quarter cif: video format with 176 × 144/120 pixels (see cif).
redundant array of independent disks: used for organizing two or more hard disks as if they were one drive. on such a drive data is shared or replicated. this is used to achieve greater capacity, reliability, and speed.
Region of Interest(ROI)
买哪种彩票中奖率最高a specific area within a field of view, used by the motion detection algorithm to identify motion.
the measure of the fine detail that can be seen in an image. for analog systems this is typically measured in television lines or tvl. the higher the tvl rating, the higher the resolution.
recommended standards for serial data transmission. a communication interface for third party control, firmware upgrades, and service purposes for camera and dvr products.
realtime transport protocol: a transfer protocol for real-time video and audio.
a measure of the amount of light required to provide a standard video signal. sensitivity values are stated in lux (see lux) or foot-candles.
an optical fiber with a silica (or glass) core with a diameter of less than 10 microns. used for high-speed transmission over long distances, it provides greater bandwidth than multimode (see multimode fiber), but its smaller core makes it more difficult to couple the light source. singlemode fiber optic transmission systems use more expensive laser-based light sources.
subnetting is a method that allows one large network to be broken down into several smaller ones. ip addresses are grouped by something called a subnet mask. every ip address has a corresponding subnet mask. the subnet mask specifies the range of the ip addresses in a group. the subnet mask looks a lot like an ip address. it is made up of four eight-bit numbers separated by periods. these numbers once again range from 0 to 255. a typical subnet mask is 255.255.255.0.
买哪种彩票中奖率最高transmission control protocol/internet protocol: a communications protocol suite that provides two data transport methods. tcp is a connection-based protocol that ensures that data arrives intact and complete. udp is a connectionless, best effort protocol that simply sends out packets. udp is typically used for streaming media, while tcp is used when error free delivery is required.
买哪种彩票中奖率最高log in protocol with which users can access a remote computer (host) on the internet or local area network (lan) connections.
camera movement in the vertical direction.
买哪种彩票中奖率最高uniform resource locator: previously universal resource locator. the unique address for a file that is accessible on the internet.
unshielded twisted pair: a variant of twisted pair cabling, utp cable is not surrounded by any shielding. the wires in a twisted pair cable are twisted around each other to minimize interference from the other twisted pairs in the cable. utp is the primary wire type for telephone usage and the most commonly used type of networking cable.
买哪种彩票中奖率最高a unique advik technology that creates invisible motion masking areas. these invisible masks are similar to privacy zones but only the camera’s algorithms can see them. this allows the camera to ignore areas of unwanted motion.
买哪种彩票中奖率最高video motion detection: an algorithm for motion detection in which the camera compares the current image with a reference image and counts the number of pixels (see pixel) that have changed between the two images. an alarm is generated when the number of pixel changes exceeds a user-configured threshold.
wide area network: a long distance link used to extend or connect remotely-located local area networks.
Changing the effective focal length to allow different fields of view to fill the picture area.
买哪种彩票中奖率最高 Zoom can be optical, where the lens is adjusted, or digital, where a portion of the view selected is magnified electronically.