for advice & estimates
AGC (Automatic Gain Control): Automatically adjusts the video quality in low light condition.
Analogue (Analogue): Continuously variable numerical values such as voltage, current, etc. (The CCD camera produces analogue video signals.)
Angle of View: The scene angle that a video camera lens can show on the monitor, like Diagonal Angle, Horizontal Angle and Vertical Angle, usually described in degree.
Aperture: The light gathering area of a lens, controlled by the iris.
ARP: Address Resolution Protocol; for mapping an IP address to a physical machine address.
Aspect Ratio: The ratio of the vertical to the horizontal image size; 4:3 is the PAL standard.
Aspherical Lens: A lens designed with a non spherical shape so that it passes more lights or decreases barrel distortion on wide angle lenses.
Attenuation: A decrease or loss in a signal, usually measured in decibels.
Auto Terminating: Automatically select the correct termination depending on whether the video output is connected.
Auto White Balance (AWB): Automatically adjusts a colour camera's colour to maintain white areas.
Auto-focus Lens: Automatically adjusts the lens focus from surrounding scene and keeps a moving object in focus.
Automatic Gain Control (AGC): Automatically adjusts the video quality in low light condition.
Automatic Iris (Auto-iris): A diaphragm device in the lens that adjusts to light level changes. The iris diaphragm opens or closes the aperture to control the amount of lights coming through the lens.
Automatic Level Control (ALC): Allows the auto-iris circuitry to either take bright spots more into consideration (peak), bringing out detail in bright areas, or less into consideration (average) bringing out detail in shadows.
Back Light Compensation (BLC): Electronically compensates for high background lighting to give detail which would normally be silhouetted.
Bandwidth: The capacity of the transmission medium stated in bits per second or as a frequency. Or, the amount of data that can be transmitted in a fixed amount of time. For digital devices, the bandwidth is usually expressed in bits per second (bps) or bytes per second. For analogue devices, the bandwidth is expressed in cycles per second, or Hertz (Hz).
Baud: A unit of measurement that denotes the number of bits that can be transmitted per second. For example, if a modem is rated at 9600 baud it is capable of transmitting data at a rate of 9600 bits per second.
Bit: Abbreviated with small "b". Binary Digit. The smallest unit of data in a computer.
Blanking: The process whereby the beam in a CRT is cut off during the retrace period.
BNC: Bayonet Neil-Concelman or British Naval Connector. A connector widely used in the CCTV industry, usually for coaxial cable. Easy to install and reliable with little video signal loss.
bps: Bits Per Second is the unit used for measuring line speed, the number of information units transmitted per second.
Brightness Control: The manual bias control on a cathode ray tube or other display device that controls the average brightness and the contrast of a picture.
Byte: Abbreviated with capital "B". A unit of data that is eight bits long and is used by most computers to represent a character such as a letter, number or symbol.
C-Mount: An industry standard for lens mounting. C-Mount is 1-inch diameter with 32 threads per inch. A C-Mount lens needs a C-ring when it is mounted on a CS-Mount camera.
Camera format: Video camera's CCD chips format; 2/3", 1/3", 1/4", etc. Camera Sensor: Video image sensor. CCD or C-MOS chip.
CCD: Charge Coupled Device. A video image sensor chip.
CCIR: International Radio Consultative Committee; has made the technical recommendation for the European 625 line standard for video signals.
CCTMA: Closed Circuit Television Manufacturers Association.
CCTV (Closed Circuit Television): Is a Television system that sends a signal to one or more monitors rather than broadcasting over a public network, hence closed-circuit. A standard CCTV system will normally include a CCTV camera (for capturing video), transmitters and receivers (to transfer the video from the source to where it is recorded), a recording system (for video playback), and a monitor (for video monitoring). CCTV systems are primarily used for security purposes inside and outside buildings. However, they can also be used for specialist applications such as mobile police use and interrogation.
CMOS: Complementary - Metal Oxide Semiconductor. A video image sensor chip that produces much lower quality picture than CCD chip.
Coaxial Cable: A cable that can carry a wide range of frequencies with very low signal loss. It consists of a metallic shield with a single wire placed along the center of a shield and isolated from the shield by an insulator.
Colour Saturation: The degree of mixture of a colour and white. High saturation means little or no white.
Composite Video Signal: A combined signals in a television transmission. The picture signal, blanking signal, and vertical/horizontal synchronizing signals are all combined.
CRT: Cathode Ray Tube. The vacuum tube part of a monitor or television.
CS-Mount: An industry standard for lens mounting. CS-Mount is 1 inch diameter with 32 threads per inch. A C-Mount lens needs C-ring when it is mounted at a CS-Mount camera.
DC Power: Direct Current Power; can be derived from an AC adapter or from a battery. Among DC voltages of 6, 9, 12, 24, 28, 12VDC is most common in the CCTV industry.
DIP Switches: Dual Interface Poll switches usually allow you to change the configuration of a circuit board to suit your application.
DSL: Digital Subscriber Line. A technology for bringing higher-bandwidth information to homes and businesses over ordinary copper telephone lines.
DVR: Digital Video Recorder; records video pictures digitally.
Dwell Time: The length of time a switcher displays one camera before sequencing to the next.
EIA: Electronic Industries Association. American standard for B/W camera system.
ELC (Electronic Light Control): Compensates for moderate light changes in indoor applications without the use of auto iris lenses. Select this mode when a fixed iris lens or manual iris lens is used.
Electronic Shutter: Compensates for moderate light changes in indoor applications without the use of auto iris lenses.
Ethernet: The most widely installed Local Area Network (LAN) technology. Specified in a standard IEEE802.3.10/100 BASE-T, the most commonly installed Ethernet system, provides transmission speed up to 100 megabits per second.
f-number (f-stop): Optical or lens speed. Smaller f-number means faster lens.
Fiber-Optic Cable: One of the video transmission ways, being used for a long distance transmission up to miles.
Field: One video frame is composed of two fields; one field consists of the odd numbered lines in the frame and the other field consists of the even numbered lines.
Field Of View (FOV): The width, height or diameter of a scene to be monitored. Usually determined by the focal length of a lens, the sensor format and the distance to the objects.
Flash Memory: Or flash RAM (Random Access Memory). A type of constantly powered non-volatile memory that can be erased and reprogrammed in units of memory called blocks.
Focal Length FL. The distance from the center of a lens (or, the secondary principal point, if it has) to the focal point (sensor). The longer the focal length, the narrower is the angle of view.
Frame: A whole video image; is composed of two interlaced fields. A CCD chip produces 30 frames per second at NTSC system and 25 frames at PAL.
FTP: File Transfer Protocol. A way to exchange files between computers on the Internet.
Gamma: Degree of contrast in a video picture between output magnitude and input magnitude.
GB: Gigabyte.
Genlock: A device that adjusts the frequency of internal sync to an external data.
Ghost: A shadowy or weak image in the received picture, offset to either the right or to the left of the primary image.
Hub: As a network product, a hub may include a group of modem cards for dial-in users, a gateway card for connections to a Local Area Network (LAN), and a connection to a line.
Hz (Hertz): Frequency in Cycles per second.
Impedance: Electrical characteristic of a system or component, expressed in ohms. CCTV industry has standardized 75-ohm impedance.
Infrared (IR): Light Invisible light beyond the 750 nano-meters (red end of the visible lights).
INT: Internal sync mode that sets to internal 2:1 interlace.
IP: Internet Protocol. A set of rules to send and receive messages at the Internet address level.
IPCCTV: Internet Protocol Closed Circuit Television
Iris: An adjustable opto-mechanical aperture built into a camera that controls the amount of lights coming through the lens.
ISDN: Integrated Service Digital Network. A set of standard for digital transmission over ordinary telephone copper wire.
JPEG: Joint Photographic Experts Group. A graphic image file or a image compression algorithm.
Kb, Kilobyte, Kbps: Kilobits per second. A measure of bandwidth.
LAN: Local Area Network. A group of computers and associated devices that share a common communications line.
LED: Light Emitting Diode.
Lens Mount: The area where a lens is mounted. There are two types; C- or CS-Mount.
Lens Speed: Optical speed, expressed by f-number. Smaller f-number means faster lens.
Linux: An UNIX-like operating system. Very efficient and fast-performing system.
LL: Line Lock mode LUX Lumens per Square Meter; unit of illumination amount.
MB: Megabyte Mbps Megabits per second. A measure of bandwidth.
Mini-DIN: Multi-wire cable with Mini-DIN connectors at both ends. Usually has 4 inner wires.
Monochrome Signal: Black and White signal.
MOS: Metal-oxide Semiconductor. One of video image chips like CCD, but it produces lower quality video.
Motorised Lens: A camera lens equipped with small electric motor that enables focusing lens, opening or closing the iris diaphragm, or changing the focal length.
MPEG: Moving Picture Experts Group. A standard for a digital video & audio compression.
MUX: Combines two or more video/audio signals into one channel. Usually accepts 10 or 16 video inputs and displays them in various formats.
Noise: Undesired signals that corrupt the original video signals and may reduce the image quality.
NTSC: National Television System Committee; formulates standards for American colour television system. NTSC system has 525 horizontal scan lines and 30 frames per second.
PAL: Phase Alternating Line system. A colour television system used in Europe, Australia, parts of Africa and the Middle East. It has 625 horizontal scan lines and 25 frames per second.
Pan: Rotating or scanning a camera side ways to view an area in a horizontal direction.
Pan and Tilt: A Camera mounting device that allows movement in both side ways and up or down.
Peak-to-Peak: The amplitude difference between the most positive and the most negative excursions of a signal.
Picture Element (Pixel): Photo sensor site in an image sensor like CCD chip; converts the input light image to an electronic signal.
Pinhole Lens: A lens with a relatively small front opening so it can be used in covert application.
Pixel Picture Element: Photo sensor site in a image sensor like CCD chip; converts the input light image to an electronic signal.
PPP, Point-to-Point Protocol: For communications between two computers using a serial interface.
PPPoE: Point-to-Point Protocol over Ethernet. Presets The pre-positioning of pan, tilt and zoom cameras by the use of potentiometers in the moving parts of the camera head. These allow the control equipment to store and move to a set reference point when the controller dictates or when an alarm exists.
PSTN: Public Switched Telephone Network. Quad Splitter Combines up to 4 video inputs into one channel and displays them on one monitor screen split into 4.
RAM: Random Access Memory. The place in a computer where the operating system, application programs, and data in current use are kept temporarily so that they can be quickly reached by the computer's processor.
RCA: The Radio Corporation of America; conveniently used to describe phono jack and plug, one of the audio/video connectors.
RG59/U Cable: One of coaxial cables suitable for video transmission in CCTV system.
Router: A device on the Internet that determines the next network point to which a data should be forwarded.
RS-232 Port: A communication port with 15 pins.
S-Video: Transmits luminance and colour portions separately, using multiple wires, thus avoiding the colour encoding process and its inevitable loss of picture quality.
SECAM: Sequential Couleur A'Memorie, a colour television system used in France, Russia and other countries that do not use either the NTSC or PAL system. It has 625 horizontal scan lines and 25 frames per second.
Sequential Switcher: Video Switcher. A device that allows the video signals from multiple cameras to be displayed on a monitor, or recorded on a VCR one at a time in sequence.
Server: A computer program that provides services to other computer programs in the same or other computers. Or, the computer that a server program runs.
Signal-to-Noise(S/N) Ratio: The ratio between the television signal and the noise; expressed in decibel (dB). The higher the number the better.
SMTP: Simple Mail Transfer Protocol. TCP/IP used in sending and receiving e-mail.
SVHS (Super Video Home System): Super VHS; a higher quality extension of the VHS home videotape format. Switcher Sequential Switcher or Video
Switcher: A device that allows the video signals from multiple cameras to be displayed on a monitor, or recorded on a VCR one at a time in sequence.
TCP: Transmission Control Protocol. A set of rules to exchange messages with other Internet points at the information packet level.
TCP / IP: Transmission Control Protocol / Internet Protocol. The basic communication language or protocol of the Internet.
Time / Date Generator: Installed between a CCTV camera and a monitor, it generates the information of Date, Time and camera ID.
TFT: Is a variant of Liquid Crystal Display (LCD) which use's Thin-Film Transistor (TFT) technology to improve their image quality. TFT LCDs are one type of active matrix LCD, though this is usually synonymous with them. They are used in both flat panel displays and projectors. In computing, TFT monitors are rapidly displacing competing CRT technology, and are commonly available in sizes from 30 to 77 cm (~12 to 30 inches). As of 2006, they have also made inroads on the television market. There is no, or minor effect on the eyes, if we use TFT-LCD monitors.
Time Lapse VCR: A video recorder that can be set to record continuously over long period of time. This can be anything from two hours to 960 hours.
VHS: Victor Home System; used by most VCRs as the recording medium - 240 lines resolution.
Video Band: The frequency band used to transmit a composite video signal.
Video Switcher: Switcher or Sequential Switcher. A device that allows the video signals from multiple cameras to be displayed on a monitor, or recorded on a VCR one at a time in sequence.
Videocassette Recorder (VCR): A device that accepts signals from a video camera/microphone and records video/audio on magnetic tape in a cassette. The VCR can play back recorded video/audio on a television set or CCTV monitor.
WAN: Wide Area Network.
Wavelet: A mathematical function useful in digital signal processing and image compression. In the Internet communications, wavelet has been used to compress images to a greater extent than is generally possible with other methods such as JPEG or MPEG.
Web Camera (or Web Camera Server): A CCTV Camera with built-in web server computer.
Web Server: The computer program (housed in a computer) that serves requested HTML pages or files.
Zoom Lens: A lens of continuously variable focal length.
PDF 219Kb
