Browse our glossary of video security terms.
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3-Axis Mounting Bracket / 3-Axis Gimbal
Cameras that feature a 3-axis mounting bracket (bullet cameras) or 3-axis gimbal (dome cameras) allow you to mount the camera virtually anywhere (wall or ceiling) and position the camera at any angle to achieve the field of view you desire.
Access Control (Physical)
The selective restriction of physical access to a physical location or other resource.
Access Control System
An interconnected set of controllers that manages the entrances and exits of secure areas, granting or denying access to individuals.
Adaptive Contrast Enhancement (ACE)
ACE works to increase contrast locally, and brings out image details to produce crisp, highly-detailed images.
Angle of View
May be expressed in Diagonal, Horizontal or Vertical. Smaller focal lengths give a wider angle of view.
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.
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.
The opening of the lens that controls the amount of light reaching the surface of the pickup device. The size of the aperture is controlled by the iris adjustment.
The ratio of width to height for the frame of the televised picture. 4:3 for standard systems
Auto Back Focus
The camera automatically and seamlessly allows users to adjust focus of images, enabling quick and easy installation.
Auto Iris Lens
A lens with an electronically controlled iris, allowing the lens to maintain one light level throughout varying light conditions.
Enables the camera to pan in and provide a detailed view of pre-defined, specific areas, with adjustable speed and holding times.
Auto White Balance
The ability of a color camera to automatically balance flushes of white light into the aperture.
Automatic Gain Control (AGC)
A function on the camera (and many electronics) that automatically balances the gain, or volume, of the signal, with the ability to raise the volume if it is too low and lower it if too high.
A mechanical adjustment in a camera that moves the imaging device relative to the lens to compensate for different back focal lengths of lenses. An important adjustment when a zoom lens is fitted.
A transformer that levels out impedance differences, so that a signal generated on to a coaxial cable can be transferred on to a twisted pair cable.
Bandwidth is defined as either channel capacity or maximum throughput on your network.
The dark parts of a video signal corresponding to approximately 0.3 volts.
BLC (Back Light Compensation)
A feature of modern CCD cameras, which electronically compensates for high background lighting, to give details that would normally be silhouetted.
BNC (British Naval Connector) is a connector used between coaxial cable and an input/output port, either male or female, in CCTV installations.
The approximate size of a camera image pickup device. This measurement is derived from the diagonal line of a chip. Common formats are 1/6 in, 1/4 in, 1/3 in, 2/3 in and 1 in.
A twisted pair type of cable used for network cabling and access control data functions.
Charge coupled device, a flat thin wafer that is light sensitive and forms the imaging device of most modern cameras. Size is measured diagonally and can be 1/3 in - 1/2 in or 2/3 in. There are two types, frame transfer and interline transfer.
CCD Image Sensor
A light-sensitive imaging device that’s available in many network IP video cameras. The CCD image sensor transforms light into electronic signals and provides strong light sensitivity, to capture video in low light conditions.
960H Image Sensor
View and record high-resolution video. A security camera with a 960H image sensor works with a 960H DVR to deliver a 33% larger image and provide sharper, more detailed video than standard DVRs which record at D1 resolution. 960H produces a wider image than CIF or D1. This reduces image stretching on widescreen monitors, which is a common problem with lower resolutions.
Determines how many cameras can be recorded at one time. For example, a four-channel DVR allows you to record and view up to 4 video cameras simultaneously.
The European 625 line standard for the video signal.
An industry standard for mounting a lens to a camera with a 1 in x 32 thread and a distance from the image plane of 17.52 mm from the shoulder of the lens. A C-mount lens may be used with a CS-mount camera with a 5 mm adapter ring.
An industry standard for mounting a lens to a camera with a 1 in x 32 thread and a distance from the image plane of 12.52 mm from the shoulder of the lens. A CS-mount lens may not be used on a C-mount camera.
A type of cable capable of passing a wide range of frequencies with very low signal loss.
The reduction in gain at one level of a picture signal with respect to the gain at another level of the same signal.
Concealed Cable Management
Where the camera video and power cables are fed through a built-in mounting bracket, protecting the wiring from vandals and criminals, and to provide a cleaner installation. For applications requiring external wiring, there may be a gap in the base of the camera's mounting bracket for convenience.
Full resolution that displays 720 x 480 pixels (NTSC).
Day/night cameras are designed to work equally well in low light conditions as during the daytime. Digital day/night cameras use an electronic filter to block out infrared light during the daytime to produce true-to-life color images. At nighttime the camera switches to black & white mode which enables it to view infrared light and capture clear black and white images of the area under surveillance.
Day/night cameras with true day/night (ICR) deliver a sharp image in low light and nighttime conditions. An IR cut filter blocks out infrared light to produce true-to-life color images during the daytime. In low light conditions and at night, the filter is removed, letting infrared light pass through to provide crisp, well-defined black and white images.
Depth of Field
The in-focus range of a lens or optical system. It is measured from the distance behind an object to the distance in front of the object when the viewing lens shows the object to be in focus.
Depth of Focus
The range of sensor-to-lens distance for which the image formed by the lens is clearly focused.
Digital Noise Reduction (DNR)
Digital Noise Reduction (DNR) technology offers several benefits. First, DNR delivers a cleaner signal, resulting in up to 70% disk space savings - so you can store more video evidence on your hard drive. Next, cameras equipped with DNR technology deliver a more visually appealing image, making it easier to identify suspects. Finally, DNR technology makes it easier for your camera to distinguish between true motion and image noise - allowing for your DVR to be more efficient in motion detection - especially in low light conditions. How it works: The chip in a camera is constantly picking up noise (fine static) in your images, especially in low-light modes. DNR technology compensates for this, correcting imperfections in the image by removing a large percentage of this noise. When a DVR or computer is processing the video data, it must compress and save every part of the image that is moving. The less noise in the image, the less data the DVR will save, and the more real motion it will detect.
2D + 3D Digital Noise Reduction (DNR)
2D + 3-D DNR incorporates frame-to-frame noise reduction with spatial noise reduction to produce clear video images with less noise, in low light conditions. Noise reduction is critical for video because noise affects image quality. Cameras with 2D + 3-D DNR produce sharper, more accurate video images with less ghosting.
3D Digital Noise Reduction (3D-DNR)
3D-DNR incorporates frame-to-frame noise reduction with spatial noise reduction to produce clear video images with less noise, in low light conditions. Noise reduction is critical for video because noise affects image quality. Cameras with 3D-DNR produce sharper, more accurate video images.
Digital Signal Processing
An algorithm within the camera that digitizes data (the image). Examples include automatic compensate for backlight interference, color balance variations and corrections related to aging of electrical components or lighting. Functions such as electronic pan and zoom, image annotation, compression of the video for network transmission, feature extraction and motion compensation can be easily and inexpensively added to the camera feature set.
Digital Slow Shutter
Allows you to see clear images in extreme low light conditions without the need for artificial illumination. DSS technology (also known as 'sens-up' or 'sense-up') enables very low light capabilities by slowing down shutter speed to allow more light to be collected by the CCD imager. This means that the camera can capture color images in conditions of near darkness. The user can adjust these settings to specify conditions that engage this feature automatically.
Digital Wide Dynamic Range (D-WDR)
Enables the camera to produce clearer images in less than ideal lighting conditions. D-WDR balances the contrast of light and shadow to improve visibility in dark areas within a scene.
The deviation of the received signal waveform from that of the original transmitted waveform.
In access control systems, a door controller is a data gathering device that often includes software to make access control decisions.
A plate mounted on the door jamb to accept and restrain a bold when the door closes.
A type of switch that communicates whether a door is open (switch open) or closed (switch closed).
Some DVRs feature dual NICs (network interface cards) to enhance security and throughput by enabling your IP cameras to run on a separate network. This minimizes degradation of other networked applications, provides network failover protection and allows for an easier installation.
Most video security cameras will use either 24 volts AC or 12 volts DC. This video security camera offers dual voltage, enabling you to use either an AC or DC power source, eliminating the worry of whether or not your power source is compatible with your security camera.
Dynamic IP Address
An IP address that changes every time you log in to your computer. This decreases internet security risks but is less reliable than a static IP address.
Dynamic Profile Streaming
This camera feature enables you to create up to 7 different streaming profiles based on codec, resolution, and frame rate. It offers region of interest streaming capabilities for focused viewing of specific regions in the field of view for increased video and bandwidth efficiency.
Electronic Industries Alliance. Monochrome video signal standard used in North America and Japan: 525 lines 60Hz
Electronic image stabilization
This camera feature automatically stabilizes your video images and minimizes the appearance of shaky images to produce steady, sharp images.
Electric Door Strike
Door unlocking hardware that’s installed in the door jamb and works with a mechanical lock or latch mechanism. An electric door strike can be connected to a door controller which can power the strike and other door peripherals.
An electronic circuit that introduces compensation for frequency discriminative effects of elements within the television system, particularly long coaxial transmission systems.
The device will send a notification when a triggered event has occurred.
The most widely used LAN transmission network. Based on a bus network topology, it runs at a maximum speed over 100 meters of 10Mbit/s. It operates over conventional co-axial cable, thin wire co-axial cable and unshielded twisted pair cabling. This has several implementations - 10Base5 for use over conventional co-axial cable, 10BaseF for use over optic fiber, and 10BaseT for use over Unshielded Twisted Pair (UTP) cabling.
Fail Safe Door
A door that will unlock automatically in the event of a power failure to permit entering and exiting through the door.
Fail Safe Lock
An electric lock that is locked when the power is on, but automatically unlocks when there is a power failure.
Fail Secure Door
A door that automatically locks during a power failure, preventing anyone from entering, but allowing them to exit during an emergency.
Fail Secure Lock
An electric lock that is normally unlocked when the power is on, but automatically locks during power failure.
Indicates the brightness of the image formed by the lens, controlled by the iris. The smaller the F-number the brighter the image.
Field of View
The horizontal or vertical scene size at a given length from the camera to the subject.
A fixed focal lens does not allow the FOV to be adjusted; the camera's focal length is permanently set.
Flush & Surface Mount
Flexible 3-part housing construction allows indoor cameras to be flush mounted and outdoor cameras can be either surface or flush mounted. Also, the base of our dome housings is conveniently constructed to act as a back-bracket for flush mounting the camera on ceilings.
The distance from the center of the lens to a plane at which point a sharp image of an object viewed at an infinite position. The focal length determines the size of the image and angle of field of view seen by the camera through the lens. This is the center of the lens to the image pickup device.
Form C Contact
A type of relay or switch (often referred to as a single pole double throw or SPDT), that contains three connections: normally open (NO), normally closed (NC) and common.
The number of frames per second that the camera produces.
A term used to indicate the speed of a lens. The smaller the F-number the greater amount of light passes through the lens.
FTP (File Transfer Protocol)
A network protocol used to transfer files from one computer to another, or between devices connected to the network.
An increase in voltage or power, usually expressed in dB.
This is one method used on Auto Iris and Direct Drive lenses to move the iris vanes, open and closed using a coil operation.
An electronic correction carried out by the camera circuitry to balance the brightness seen by the camera to that of the monitor.
Gang Box Mounting
Provides easier, more convenient installation of indoor dome cameras, via a double gang mount pattern. This feature allows the camera to be mounted directly to installed boxes without the need for an additional plate.
A node that allows connection to another network using another protocol.
An alternating current (AC) that can be produced in a cable. This is usually caused by parts of the system being fed from different electrical sources resulting in different earth potentials at each end of the signal path. This results in interference of the video pictures in the form of a black shadow bar across the screen or as a tearing effect in the top comer of a picture.
Ground Loop Transformer
An isolation transformer. There is no direct connection between input and output.
H.264 is a stable, proven and widely used compression technology, with unbeatable recording picture quality and a small compression ratio that saves valuable hard drive storage space (5-10 times smaller than MPEG-4).
HDcctv is a standard for high definition analog-based closed circuit television technology.
HD-SDI technology delivers high quality live HD video over coax with exceptional resolution and image detail. HD-SDI technology delivers image quality that is far superior to analog CCTV and provides a cost-effective video surveillance solution that's easy to install and integrate with existing CCTV systems.
Before HD-SDI, the only way to get HD resolution was through a megapixel IP camera. HD-SDI is the future of analog and an alternative to IP.
HDMI supports standard, enhanced or HD video. Some DVRs feature an HDMI output which delivers enhanced image clarity with crisp images and enables you to view your security camera video in HD on your HDTV screen. HD images can be reproduced with the HDMI support for HD display.
The number of variations per second (e.g. picture frames, alternating of the current, etc).
Hyper text transfer protocol.
HTTP Port 80
Normally this is the HTTP port address that cameras can communicate over.
Hybrid DVR Supports both analog and IP cameras, enabling you to utilize existing legacy analog technology, while providing flexibility to migrate to an IP solution and take advantage of the many benefits of IP technology.
Impedance (input or output)
The input or output characteristic of a system component that determines the type of transmission cable to be used. Expressed in ohms.
Infrared (IR) cameras feature built-in illuminators that project infrared light, which is nearly invisible to the human eye but very visible to IR surveillance cameras. This technology allows you to capture crystal clear, black and white video of suspects who feel protected by complete darkness. IR cameras are very effective in covering targeted areas with little or no light, ranging from exterior parking areas and entryways, to interior rooms requiring 24 hour surveillance. For coverage of wider areas, consider adding an additional external infrared illuminator.
Input/Output (I/O) Device
An I/O device facilitates elevator control and multi-door monitoring (in/out only).
Internet Protocol (IP)
The primary communications protocol in the internet protocol suite for sending and receiving data packets across network boundaries.
IP-based Access Control
IP access control technology utilizes the network to provide secure network-controlled access and management of physical doors at a facility or location.
The network location of an IP camera, which can be located using a Web browser on a PC. (example – 192.168.1.100)
IP (also known as Ingress Protection) rating is a standard rating of protection offered by an enclosure (such as a security camera enclosure). An IP rating consists of the letters “IP” followed by two a two-digit number. The first number represents the level of protection an enclosure has against solids, moving parts and dust, and the second number represents the level of protection against moisture, fluids and water.
IR Illuminator Wavelengths
IR illuminators work with day/night cameras to provide IR illumination for low light environments and enable you to capture video at night. IR illuminators are equipped with varying wavelengths—generally from 730 nm to 950 nm. An IR illuminator with a 730 nm wavelength requires a less light sensitive camera and produces a strong, very visible red glow, while an 850 nm wavelength IR illuminator produces a faint visible glow, making it semi-covert. An IR illuminator with a 940 nm wavelength produces a glow that is virtually invisible to the human eye, which makes it an ideal choice for most covert applications. A 940 nm illuminator must be used with a very light sensitive camera with no IR cut filter, or if the camera does have an IR filter, it has to be removed for optimal results.
Mechanism within a lens to regulate the amount of light that passes through, and falls upon, the image sensor. It can be controlled manually or automatically.
Small, rapid variations in a waveform due to mechanical disturbances or to changes in the characteristic of components. Supply voltages, imperfect synchronizing signals, circuits, etc.
Junction Box Mounting
Outdoor dome cameras feature J box mounting enabling the camera to be directly mounted to an installed junction box, providing faster, easier installation.
A LAN (Local Area Network) consists of a group of computers and network devices that share common resources within a small physical area, such as inside an office building. A LAN uses Ethernet or Wi-Fi for network communication and typically offers high data and transfer rates.
A transparent optical component consisting of one or more pieces of optical glass with surfaces curved (usually spherical), so that they converge or diverge the transmitted rays of an object, forming a real or virtual image of that object.
The approximate size of a lens-projected image. In most cases the lens will project an image slightly greater than the designated image size to insure the pickup device is completely covered. It is recommended that camera and lenses are the same format size. A lens larger format size can be used on a smaller format camera, however a smaller format lens should never be used with a larger format camera.
Refers to the lens aperture or its ability to transmit light. This is measured in F-stops.
A camera that is synchronized to the frequency of its AC power supply.
Some fisheye or 360 cameras feature local de-warping which enables viewing of portions of the full video image produced by the fisheye without distortion.
A loop out connection enables you to run video stream from a single camera to a separate monitor on every channel. This feature is especially ideal for public view monitors and reception desks.
The automatic video loss detection feature allows you to program your DVR to alert you when your camera loses its signal due to power failure, bad weather or tampering. You can get an alert from an external device such as an alarm or trigger another camera to start recording.
A unit of incident light. It is the illumination on a surface one square foot in area on which a flux of one lumen is uniformly distributed, or the illumination at a surface all points of which are at a distance of one foot from a uniform source of one candela.
Luminous intensity (photometric brightness) of any surface in a given direction per unit of projected area of the surface as viewed from that direction, measured in footlamberts (fl).
International System (Sl) unit of illumination in which the meter is the unit of length. One lux equals one lumen per square meter.
A device that sends a signal when the magnetic field between two monitored access points is broken.
Magnetic Lock (Mag Lock)
A locking device that consists of an electromagnet and a strike plate that works in conjunction with a mechanical lock or latch mechanism, and uses electromagnetic attraction to lock and unlock a door.
Manual Iris Lens
A lens with a manual adjustment to set the iris opening (aperture) to a fixed position. This type lens is generally used in fixed lighting conditions.
A combination of electromechanical or electronic switches which route a number of signal sources to one or more designations.
Pixels are used as a unit of measure. In the security industry, it’s a measure of resolution. Mega refers to 1 million, therefore, megapixel means one million pixels. If you have a 2.0 megapixel camera, in actuality you have a 2 million pixel camera.
MIMO (multiple in, multiple out) is a method of utilizing multiple radio antennas at both the transmitter and the receiver to improve communication performance for wireless network communications.
Black and white with all shades of gray.
DVR: Allows you to pre-define motion detection zones and sensitivity for each individual camera. When motion is detected by the DVR, this will trigger a pre-programmed event (usually a recording), or it can activate an external device, such as an alarm. This benefit allows you to save hard drive space by only recording relevant video in the areas you care about. It also saves time: you don t have to sift through countless hours of useless video where nothing is happening - you can quickly scan through the captured activity in the pre-defined area of coverage.
Camera: Allows you to integrate your cameras with external devices - to engage that device upon the detection of motion. Common devices include security lights, alarms, access control devices, and more.
Moving Picture Experts Group, version 4. A form of compression that makes transmission and storage of images easier.
Multiplex operation enables simultaneous live viewing, recording, playback, and backup. This allows you to view live video from your DVR locally or via your network, play back existing recorded video, or make backups without stopping recording.
Enables you to set your recording resolution at one rate and watch live video at another rate.
An access control software feature that quickly verifies where individuals in a particular zone at a location for easy tracking and identification.
A filter that attenuates light evenly over the visible light spectrum. It reduces the light entering a lens, thus forcing the iris to open to its maximum.
Network IP Camera
An IP (internet protocol) or network IP camera captures and transmits live and recorded video images directly over a network. A network camera requires a high speed internet connection, router, Ethernet cable and IP address to function, and it plugs directly into your network router and transmits data through the network.
Network Video Recorder (NVR)
An NVR is a hardware box that receives video streams over a LAN (local area network) or WAN (wide area network) and records the video streams in digital format onto a hard disk. Recording and playback of video can be managed remotely from any compatible device such as a PC, laptop or smartphone that is connected to the network.
The word "noise" originated in audio practice and refers to random spurts of electrical energy or interference. In some cases, it will produce a "salt-and-pepper" pattern over the televised picture. Heavy noise is sometimes referred to as "snow".
Network time protocol.
A central source that can set the time of all network devices.
National Television Standards Committee. Color Video Signal standard used in North American and Japanese: 525 Lines, 60Hz.
On Screen Display
A camera's On Screen Display (OSD) allows you to fine tune virtually every setting of your camera to achieve the best possible image quality. Without OSD, you are dependent upon the factory settings of the camera, and subject to any impact to the camera experienced during delivery or installation. With the convenient design features of DIGIOP Black cameras, including 2nd video out and on-board one-finger joystick controls, you can adjust your every aspect of your camera at the point of installation - without having to run back-and-forth to your DVR or monitor. Aspects you can control include wide dynamic range, auto iris exposure settings, day/night settings, and many more.
An ONVIF compliant product conforms to ONVIF (Open Network Video Interface Forum) specifications for IP-based security products. ONVIF defines a common protocol for the exchange of information between different network video devices from different manufacturers, to allow greater interoperability in multi- vendor network video systems.
The signal level at the output of an amplifier or other device.
This optional feature allows you to prevent files from being overwritten when the hard drive is full, or you can pre-program the DVR to overwrite recorded video to ensure continuous recording—it’s your choice.
Pan & Tilt
A device that can be remotely controlled to provide both vertical and horizontal movement for a camera.
The measurement of a video signal from the base of the sync pulse to the top of the white level. For a full video signal this should be one volt.
Some IP-based door controllers in an access control system are independent of a network or PC work station and feature peer-to-peer communication which keeps data flowing, even if a server connection is interrupted.
The ability to delay the line locking process so as to align cameras fed from AC voltages of different phases.
A device at the receiving end of an optical fiber link that converts light to electrical power.
A device that automatically switches on the infra-red lights when light levels fall to a pre-set level.
An electronic device that superimposes the view from one camera over that of another.
Privacy Zone Masking
This security camera feature enables you to set privacy zones for select areas within the field of view, that need to be kept private while viewing and recording video.
Power over Ethernet
PoE allows IP (internet protocol) devices to receive power and data over existing LAN (local area network) cabling; eliminating the need to install a separate power cable, simplifying installation and lowering cabling costs.
Power Over Ethernet+ (PoE+)
This feature enables high-draw PTZ camera to utilize Power over Ethernet (PoE) on a single CAT5 cable.
Video signals are generated using horizontal lines. Progressive scan, also referred to as non-interlaced scanning, draws every line of an image in sequence. The main advantage with progressive scan is that motion appears smoother and more realistic.
A common access control card technology that uses radio frequency to communicate between a proximity card and a reader.
Proximity Card (Prox Card)
A access control credential that is encrypted with proximity technology and can be read by a proximity reader without having to physically insert the card into the reader, in order to grant a cardholder access to a location.
Proximity Reader (Prox Reader)
A device that can read encoding on access control credentials such as a proximity card or badge, and sends data to a controller to grant or deny access.
PTZ (Pan, Tilt Zoom)
A pan-tilt-zoom camera is a camera that is capable of remote directional and zoom control.
A product that can display the views from 4 cameras simultaneously on one monitor. It is also possible to select any individual camera for full-screen display on real time monitoring, dependent on model.
A method of combining two fields to make one frame where strict timing is not a requirement.
Request to Exit Button (REX) In access control, a button that must be pushed to release the door in order to exit.
The ratio of light returned from a surface expressed as a percentage.
Scene illumination multiplied by reflectance. This is the amount of light returned to the camera and determines the quality of p