Glossary of Terms

AC Adapter – A power transformer which is plugged into AC Power. This adapter converts standard 125 VAC/60 Hz (Wall outlet output in US) to 12VDC or 24VAC, it is best to use Regulated adapters only.

AC Power – Alternating Current Power is the standard output from a United States Power outlet; 125 VAC/60Hz. This power source is not polarity sensitive.

Automatic Gain Control – AGC Automatically adjusts the video for lower light conditions

Alarm Sensor – A Sensor that a triggered when an alarm condition is met (i.e. Motion alarm)

Automatic Light Control – Controls Auto-Iris lens, attempting to adjust the image to varying light conditions. Select ALC mode when an auto-iris lens is used.

Analog – Variable numeric values in relation to a signal. CCTV cameras that transmit video using coaxial cable are considered analog cameras.

Aperture – Term for the area on a lens in which light gathers and is controlled by the Iris

Anti-Passback – Anti-Passback is an access control security measure that prevents a Cardholder from passing his or her access card to an individual behind them, and allowing them access into a secured zone.

Anti-Tailgating – The term “tailgating” refers to instances when one person swipes their access card and another person or vehicle “tailgates” them on the entry. Anti-Tailgating is an access control security measure that will not allow a Cardholder to exit a Zone that they never entered as a valid credentialed user.

Aspect Ratio – The ratio between the width and height of an image. The Aspect Ratio is usually written in ratio form, 3:4 is the NTSC standard

Aspherical Lens – A lens designed so that it passes more light by decreasing distortion on wide angle lenses.

Auto-focus Lens – Lens designed to obtain correct focus on a subject automatically.

Automatic Iris – A lens that automatically adjusts to light changes by opening and closing the aperture; also known as “Auto-Iris”.

Auto White Balance – AWB Automatically adjusts the cameras image to maintain white areas.

Bandwidth – The Capacity of a transmission usually stated in a frequency or as Bits per Second (Bps).

Back Light Compensation – BLC Automatically attempts to compensate for high background light so that an image which would be normally shadowed is not.

BNC – British Naval Connector; A widely used connection in CCTV which is attached to a coaxial cable.

C-Mount – A type of lens mount, 12.5 mm. in depth. A C-Mount lens needs C-ring when it is mounted to a CS-Mount camera.

Camera Format – Video camera's CCD chips format; 2/3", 1/3", 1/4", etc. (essentially Aspect Ratio)

Camera Sensor – Video image sensor usually written as a CCD or C-MOS sensor..

CCD – a Charge Coupled Device is a video image sensor chip that is expressed as an aspect ratio, most commonly being a 1/3”.

C-MOS – (Complementary – Metal Oxide Semiconductor) chip, also a video image sensor, produces much lower quality picture than CCD chip.

CCTV – Closed Circuit Television is a system that does not send out signals but transmits them on a closed circuit through either cable or wireless transmission.

CMOS – Complementary Metal-oxide Semiconductor is a video image chip similar to CCD but produces a lower quality image. This type of lens is usually fitted to smaller cameras and generally uses less power than CCD chips.

Coaxial Cable – A cable that carry video signals. The cable consists of a metallic shield with a single wire placed along the center, which is insulated and connected on the ends, usually with a BNC connector. RG59 is common for CCTV use and can be installed normally up to a 700ft distance without losing video quality.

Color Saturation – The degree of mixture of a color and white. High saturation means little or no white.

Component Video – Video information that is transmitted as two or more separate signals, opposite of composite video.

Composite Video – A combined signal in a transmission.

CRT – Cathode Ray Tube. A tube within a monitor or television that uses light to form an image on the screen.

CS-Mount – A type of lens mount, 12.5 mm. in depth. A C-Mount lens needs C-ring when it is mounted to a CS-Mount camera.

DC Power – Direct Current Power that is created through either an AC adapter or a battery. 12 volt or 12VDC is the most common DC power in CCTV. DC power is polarity sensitive.

DIP switches – Dual Interface Poll switches allow you to change the settings on your camera to better suit your situation.

DHCP – The Dynamic Host Configuration Protocol; allows network administrators to manage their networks for automation of IP addresses.

DNS – Domain Name System is a data query service for the lookup of host IP addresses

DSL – Digital Subscriber Line. A technology for bringing higher-bandwidth information to homes and businesses over ordinary copper telephone lines.

DVR – A Digital Video Recorder records images digitally onto hard drives (HDD).

Dwell Time – The length of time a switcher or device which has a “switching” function stays on an image before moving on to the next.

ELC – ELC adjusts to moderate light changes generally in an indoor application. This mode should be used when a manual Iris lens is used.

Electronic Shutter – Compensates for moderate light changes in indoor applications without the use of auto iris lenses.

EMI – Electro-Magnetic Interference.

Ethernet – A family of frame based network technologies for Local Area Networks; one of the most widely installed LAN technologies which is specified as IEEE802.3.10/100 BASE-T

FCC – The Federal Communications Commission is a United States Government commission to regulate airwaves within the US.

FFL – Fixed Focal Length Lens.

Fiber – Optic Cable – A cable containing one or more optical fibers for transmission of video or data signal, usually for extreme distances.

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 Frequency – The Amount of fields per second, stated as IPS or Images Per Second

Field Of View – FOV is the amount of viewing area you have (Length, Width, and Depth), usually stated in degrees (i.e. 60 degree FOV).

Flex Channel – A flex channel is an input channel on a security digital video recorder (DVR) that can be configured to support either an analog or IP video stream, providing complete flexibility to connect either an analog or an IP camera to the DVR, and to switch the video input at any time.

FlexVR™ – Unlike traditional hybrid DVRs, which offer a pre-determined number of analog and IP channels, DIGIOP FlexVR™ Hybrid DVRs can be configured to support any combination of analog and IP video streams—within the total number of channels supported by the DVR. Channels can be converted to support either analog or IP cameras at any time, and all channels are pre-licensed and fully enabled—delivering the ultimate in system flexibility and cost-effectiveness.

Focal Length – FL is the distance from the center of the lens to a point of focus or focal point stated in millimeters. To determine the Focal length needed for your situation refer to the Lens calculator on our web site.

Firewall – A program or programs that provides protection against threats or intruders into your network.

f-number – Also known as an F-stop, it is the optical speed of a lens. The smaller the f-number the faster the lens. Shown as a number like F1.4 and F2.0.

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.

Frame Frequency – The number of frames per second. The frame frequency is half the field frequency.

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 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) – 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 nanometers(red end of the visible lights).

Intranet – A private network. It may consist of many LAN and/or WAN.

IP – Internet Protocol. A set of rules to send and receive messages at the Internet address level.

IP (Code) (Ingress Protection) – Classifies the level of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and water. Common camera ratings are IP65 and IP66

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 (JPG) – Joint Photographic Experts Group. A graphic image file or an 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. LAN, Local Area Network or WAN, Wide Area Network has intranet network in a limited area or organization and has a lot of computers connected to the network. Web camera servers, as like other computers, can be connected to LAN or WAN so that other computers can share the video data. Web camera server scan be connected to LAN or WAN through RJ45 jacks.

Lens Mount – The area where a lens is mounted. There are two types; C- or CS-Mount.

C-Mount Lens The flange back (distance from the surface where the lens comes in contact with the camera to the focal point) of C-Mount lens is 17.526mm(0.69 inch). This is the only difference between the C-Mount lens and CS-Mount lens. C-Mount lens, as well as CS-Mount, is 1 inch diameter with 32 TPI (threads per inch). A C-Ring (5mm spacer ring) is required when a C-Mount lens is to be mounted to a CS-Mount camera unless the camera has built-in Flange-back Adjusting Ring.
CS-Mount Lens The flange back of CS-Mount lens is 12.5mm(0.492 inch). This is 5mm shorter than the C-Mount lens and you need a 5mm spacer ring (or, C-ring) when you mount a C-Mount lens to a CS-Mount camera. (So, CS-Mount camera is always compatible with C- or CS-Mount lens. But, C-Mount camera is not compatible with CS-Mount lens. Most professional cameras are CS-Mount cameras and include a C-ring).


Fixed Mount Lens – While C- or CS-Mount lens can be changed according to your application, the fixed mount lens, usually found on board cameras and mini cameras does not have standard mount size and can not be changed as easily as C- or CS-Mount lens.

LL – Line Lock mode

Lux – Lumens per Square Meter; unit of illumination amount.

About Illumination


To see properly, a video surveillance camera requires a certain amount of lights produced by natural or artificial illumination. B/W cameras work with any type of light sources, but color cameras need lights that contain all the colors in the visible spectrum.
The amount of lights is defined by LUX. One LUX is a candle light volume at one meter distance. Followings are some examples of natural lights expressed in LUX.
Full daylight: 10,000 LUX
Very dark day: 100 LUX
Twilight: 10 LUX
Deep twilight: 1 LUX
Full moon: 0.1 LUX
Quarter moon: 0.01LUX
A good B/W camera can see in full moon condition. But, a color camera will need an additional artificial light in full moon.


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.

MOD (Minimum Object Distance) – The closest distance a lens will be able to focus upon an object. Wider angle (shorter focal length) lenses generally have a smaller MOD than larger focal length (narrower angle) lenses.

Motorized 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.

Multiplexer (MUX) – Combines two or more video/audio signals into one channel. Usually accepts 10 or 16 video inputs and displays them in various formats.

Network – A series of points or connection points interconnected by communication paths.

Noise – Undesired signals that corrupt the original video signals and may reduce the image quality.

NTSC – National Television System Committee; formulates standards for American color television system. NTSC system has 525 horizontal scan lines and 30 frames per second.

NVR – Network Video Recorder. A software or computer that records video on the hard disk. Like a DVR, it usually records digitally so the user can instantly search by time, date and camera. It collects video from network camera, network video server or DVR over the network.

Open IP License – DIGIOP’s Open IP License delivers a simple and cost-effective licensing structure for video recording solutions. All video channels come pre-licensed and fully-enabled, allowing users to add cameras as their system needs require (up to 32 channels per system), without having to purchase additional licenses. Licenses never expire and there are no recurring fees, minimizing total cost of ownership over the life of the product.

Optical Speed – Lens speed, expressed by f-number. Smaller f-number means faster lens.

PAL – Phase Alternating Line system. A color 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 and Tilt (see also PTZ) – A Camera mounting device that allows movement in both side ways and up or down.

Pan – Rotating or scanning a camera side ways to view an area in a horizontal direction.

Pelco (P or D) – An industry standard protocol for controlling PTZ cameras.

Pinhole Lens – A lens with a relatively small front opening so it can be used in covert application.

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.

Protocol – A special set of rules (in information technology).

PTZ – A camera that is able of panning, tilting, and zooming by remote control.

Quad Splitter – Combines up to 4 video inputs into one channel and displays them on one monitor screen split into 4.

RCA – The Radio Corporation of America; conveniently used to describe phono jack and plug, one of the audio/video connectors.

Resolution – Expressed by TV lines or pixels, it indicates the quality level of video images.

R.E.T.R – Remote Event Trigger Recording When R.E.T.R. is enabled and any event recording is triggered, the recorded file will be saved on your PC.

RF – Radio Frequency.

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.

Sequential Couleur A'Memorie, a color 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.

Switcher or 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.

S-Video – Transmits luminance and color portions separately, using multiple wires, thus avoiding the color encoding process and its inevitable loss of picture quality.

TCP/IP – Transmission Control Protocol / Internet Protocol. The basic communication language or protocol of the Internet.

TFT – Thin Film Transistor, a type of LCD flat-panel display screen. The TFT technology provides the best resolution of all the flat-panel techniques, but it is also the most expensive. TFT screens are sometimes called active-matrix LCDs.

Time/Date Generator- Installed between a CCTV camera and a monitor, it generates the information of Date, Time and camera ID.

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.

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.

Video Switcher or 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.

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.


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