CCTV Glossary

1080P
Refers to resolutions of High Definition (HD) Digital Video Recorders (DVRs). Equivalent to 1920px x 1080px = 2073,600 (2 Mp). This is also termed Full HD.

720P
Refers to resolutions of High Definition (HD) Digital Video Recorders (DVRs). Equivalent to 1280px x 720px = 921,600 (1 Mp). This is also termed HD.

960H
Refers to resolutions of standard Digital Video Recorders (DVRs). Equivalent to 960px x 480px = 460,800 (0.5 Mp). This is also termed WD1 and is simply the widescreen version of D1

AGC
Automatic Gain Control – usually used in audio amplifiers and some high spec CCT^V cameras to effectively smooth out variations in signal levels.

Analogue
An adjective used to describe the transmission of audio and video signals by means of a variable voltage.

Automatic Exposure
Abbreviated as AE is usually a standard feature on CCTV cameras that automatically determines the correct exposure for pictures without any user input.

BLC
Back Light Compensation – attempts to reduce the contrast in a high contrast image such as a highly backlit one so that the subject in front of the backlit contains some detail.

BNC
The Bayonet Neill–Concelman connector is a miniature quick connect/disconnect connector used for coaxial cable. It features two bayonet lugs on the female connector; mating is fully achieved with a quarter turn of the coupling nut.

Bullet Camera
Cylindrical style camera usually fitted with a swivel mounting bracket.

CMOS
The Complementary Metal Oxide Semiconductor is commonly used in CCTV cameras. It was historically perceived to be inferior to CCD sensors but technological advances have brought the two technologies to a similar performance level.

CVBS
Colour, Video, Blanking, and Sync is composite video usually used in standard formats such as PAL and NTSC.

DDNS
Dynamic DNS is a service that maps Internet domain names to IP addresses. DDNS allows anyone hosting a Web server to advertise a public name to prospective users. DDNS is designed to also support dynamic IP addresses, such as those assigned by a DHCP server. That makes DDNS a good fit for home networks, which normally receive dynamic public IP addresses from their Internet provider that occasionally change.

DHCP
DynamicHostConfigurationProtocol is a protocol for assigning dynamic IP devices on a network. With dynamic addressing, a device can have a different IP address every time it connects to the network. In some systems, the device’s IP address can even change while it is still connected. DHCP also supports a mix of static and dynamic IP addresses.

D/N
Day/Night – indicates that the camera can work at night. Cameras will switch to black and white and will produce video when IR illumination is used.

DNR (3D)
Dynamic Noise Reduction – cameras fitted with DNR produce sharper images than those without and cameras with 3D DNR have very little noise on the video.

DNS
Domain Name System – simply the hierarchical naming and addressing network components.

Dome Camera
Dome cameras have the lens and IR LEDs (if fitted) enclosed in a clear dome. The lens assembly is usually fitted on a gimbal to allow the required field of view to be captured.

DVR
Digital Video Recorder – digital recorder for recording digitized images from analog cameras onto a recording medium – usually a Hard Disk Drive (HDD).

DWDR
Digital Wide Dynamic Range – a system of digitally increasing the dynamic range of CCTV cameras. The benefits are debatable. Not as good as ‘True WDR’

Ethernet
Ethernet is a networking protocol designed for connecting network devices over a Local area Network (LAN).   Uses CAT5/6 cable

EXIR
EXIR is an enhanced IR lighting system which improves the effectiveness of IR Lighting.

Field of View
The field of view is the area ‘seen’ by a camera at a particular distance from the camera. It is related to the Focal Length of the camera lens.

Focal Length
The focal length of a camera is the distance between the picture sensor and the camera lens. The higher the focal length, the narrower the angle and hence the narrower the field of view.

FPS (fps)
Frames per second – this is the number of video frames recorded per second. DVRs and NVRs are usually capable of recording up to 25 fps. It is usually not necessary to record at 25 fps.   Normal speed motion looks fine at 12fps. Lowering the fps significantly reduce the recording overhead.

Eyeball Camera
These cameras comprise an orbital socket and a movable camera fitted into the socket. They are sometimes referred to as turret cameras.

G.711u
G.711 digitizes analog audio signals producing output at 64 kilobits per second.

H264
A video codec standard which can achieve high-quality video in relatively low bitrates.

HD
High Definition – in CCTV terms this refers to systems capable of recording at 720p (1 Mp) or higher.

HDMI
High-Definition Multimedia Interface is a proprietary audio/video interface for transferring uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a DVR or NVR, to a compatible computer monitor, digital television or other devices.

HD-CVI
High Definition Composite Video Interface is a means of transmitting and receiving high definition (up to 1080p) CCTV images over Coaxial cable. CVI is a closed license technology from Dahua. It will probably be superseded by HD-TVI.

HD-SDI
High Definition Serial Digital Interface is a means of transmitting and receiving high definition (up to 1080p) CCTV images over Coaxial cable. SDI can use existing coax cable but the cable has to be in excellent condition.

HD-TVI
High Definition Transport Video Interface is a means of transmitting and receiving high definition (up to 1080p) CCTV images over Coaxial cable. TVI is backward compatible with existing cameras and cable in analog systems.

ICR (or IRC)
Infra-Red Cut filter. Image sensors are designed to be sensitive to IR light; however, during daytime color viewing, the IR would ruin the image.   To prevent this, cameras are fitted with an IR cut filter which prevents the IR reaching the image sensor. As the light level falls the camera will revert to black and white and the IR filter is removed. Low-end cameras attempt to do this via the software in the camera. The software method is not very good – it tends to produce strange color balances in daylight viewing. High-end cameras have a mechanical filter which flips in front of the image sensor – usually accompanied by an audible click.

IP (CCTV)
IP CCTV uses Internet Protocol devices to transmit/receive data (images and audio) digitally as opposed to analog.   Each IP device on a system will have an individual IP address as part of the same subnet. E.g. An NVR may have the address 192.168.0.10 and the cameras 192.168.0.11, 192.168.0.12 etc.

IP (weatherproof)
Ingress Protection – for outdoor use a minimum of IP66 is recommended.

iSCSI
Stands for Internet Small Computer System Interface, works on top of the Transport Control Protocol (TCP) and allows the SCSI command to be sent end-to-end over local-area networks (LANs), wide-area networks (WANs) or the Internet.

LAN
Local Area Network – a network of IP devices connected locally as opposed to a WAN which is connected over the Internet.

LUX
The lux is the SI unit of luminance. It is equal to one lumen per square meter.

Motion Detect
All high-end DVRs and NVRs are capable of configuring individual cameras to detect motion within a user-selectable are of the image. When motion is detected, the DVR can start recording and/or produce an alarm signal.

NFS
Network File System – allows files to be viewed over a network in the same way that those files could be viewed locally.

NTP
Network time Protocol – allows devices to be set to the international time standard via the internet.

NTSC
NTSC is the video system or standard used in North America and most of South America. 30 frames are transmitted each second. Each frame is made up of 525 individual scan lines.

NVR
Network Video Recorder – the recorder used in IP CCTV systems.

ONVIF
ONVIF is a global and open industry forum with the goal of facilitating the development and use of a global open standard for the interface of physical IP-based security products. Or in other words, to create a standard for how IP Products within video surveillance systems and other physical security areas can communicate with each other.

PAL
Phase Alternating Line (PAL) is a color encoding system for analog television used in broadcast television systems in most countries broadcasting at 625-line, 25 frames per second. Now superseded by Digital Video Broadcasting,

Pixel
A Pixel is the smallest point in an addressable display device.

PoE
Power over Ethernet is a system where the power required by IP cameras is carried on the same Ethernet cable (Cat5) as the data from the camera. There are two standards – PoE and PoE+.

PPPoE
Point-to-Point Protocol over Ethernet is a specification for connecting multiple computer users on a LAN to a remote site through a modem or similar devices.

Privacy Mask
Some CCTV Cameras have the facility to mask off parts of the captured image area. This is intended to be used to prevent capturing images from sensitive areas such as a neighbors rear garden.

PTZ
Pan, Tilt, and Zoom. PTZ enabled cameras can be controlled remotely by a PTZ controller. The PTZ controller can be a physical device or software controlled via a remote viewing interface.

RCA (audio)
An RCA connector commonly referred to as a ‘phono’ plug is commonly used for the audio input/output on DVRs and cameras. It can also be used for video.

RS485
On DVRs and NVRs the alarm inputs/outputs are usually serial RS485 line drivers.

SADP
Search Active Devices Protocol software is a kind of user-friendly and installation-free online device search tool. It searches the active online devices within your subnet and displays the information of the devices. You can also modify the basic network information of devices.

SATA
Serial ATA (SATA, abbreviated from Serial AT Attachment) is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives and optical drives. All modern Hard Disk drives are SATA types.

SMTP
Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (email) transmission.SMTP by default uses TCP port 25. Modern DVRs and NVRs connected to the internet can send e-mails in response to various events.

SNMP
Simple Network Management Protocol (SNMP) is a popular protocol for network management. It is used for collecting information from, and configuring, network devices, such as servers, printers, hubs, switches, and routers on an Internet Protocol (IP) network.

TB, Tb
Terabyte – is a unit of bytes and is equivalent to 10244 or 1000 Gigabytes. In CCTV systems it is used as teh hard disk capacity measurement.

TCP/IP
Transmission Control Protocol/Internet Protocol is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet).

Turret Camera
Also referred to as an eyeball camera.

TVL
TV Lines is a measurement of the resolution of analog systems and is a legacy or PAL and NTSC TV systems.   Analog cameras are still quoted in TVL. Note that the maximum resolution of standard analog systems is 700 TVL and cameras specified as say 1000 TVL are no better than those specified as 700 TVL.

UPnP
Universal Plug and Play (UPnP) is a standard that uses Internet and Web Protocols to enable devices such as PCs, peripherals, intelligent appliances, and wireless devices to be plugged into a network and automatically know about each other. With UPnP, when a user plugs a device into the network, the device will configure itself and acquire an IP address.

USB
Universal Serial Bus, an external bus standard that supports data transfer rates of 12 Mbps.  DVRs and NVRs are usually fitted with 2 or more USB ports for connecting a mouse and an external storage device such as a memory stick or hard disk drive.

UTC
Up The Coax is a system of controlling a PTZ enabled camera using coax cable to carry the signals.   Requires the use of a UTC controller.

VGA
Video Graphics Array. DVRs and NVRs are fitted with a VGA connector for output up to 1080p. Modern DVRs and NVRs are also fitted with HDMI connectors which reputedly have less signal loss.

WAN
Wide Area Network. When the DVR or NVR is connected to the internet it becomes part of the WAN.

WDR (True)
Wide Dynamic Range. Cameras with wide dynamic range capability are commonly used in CCTV systems, and some medical applications. In surveillance, WDR is intended to provide clear images even under backlighting, where the intensity of illumination varies a lot—namely when there are very bright and very dark areas simultaneously in the camera’s field of view. WDR allows an imaging system to correct for any intense back-light surrounding a subject and thus enhances the ability to distinguish features and shapes on the subject.