CCTV Glossary

By: Randy Bragg, MBA, MISM

Aperture - Aperture is the area of the camera lens that gathers light. The iris of the CCTV lens controls the size of aperture.

Auto Iris - Auto Iris Lenses adjust for changing light conditions in a camera view. If the sun shines on a camera with an auto iris lens, the lens will adjust the amount of light so the picture remains clear.

CCD Charge Coupled Device is a light sensitive imaging device for almost all cameras. Typical sizes for CCTV cameras - 1/2", 1/3", and 1/4".

C Mount The C Mount is the type of screw-on mounting for CCTV camera lenses. C Mount lenses need an adapter ring when used with CS mount camera (see CS Mount).

Compression Compression techniques are used in Digital CCTV to reduce the file sizes of recorded video images. Typical compression formats used for video are: MJPEG, MPEG-4 & H.264.

CS Mount The CS Mount is the more recent type of mounting for CCTV camera lenses. Designed for 1/2", 1/3" 1/4" CCD cameras, CS-Mount is the more common lens mount used today in CCTV cameras.

Day/Night Camera A camera that is 'Day/Night' means it can capture video in both day and nighttime. In low light conditions, the Sony Day/Night chipset switches from color to black & white at night to enhance the picture quality.

DSP Digital Signal Processing is a technique by which video quality can be improved by adjusting parameters of the video signal.

DVR Digital Video Recorder is when CCTV footage is converted to a digital signal and stored on a PC Hard Disk. This is now the standard CCTV recording practice.

ExView ExView is a Sony Chipset type that offers very good images in both day and night time. Typically, cameras with Ex-View chipset have good Low Light (LUX) levels.

F-stop F-stop is the ratio of focal length to the diameter of the lens. The smaller the F-Stop number, the more light is passed.

Field Of View The view of the camera in relation to the angle of view and distance of the object from the lens.

Frame A frame consists of 2 interlaces fields. 30 frames are created every second.

Frame Rate The quality of a digital surveillance system is often determined by the total frame rate it can record at. The higher the frame rate, the higher the quality of recording and the more real time your CCTV recording will be - real time recording for 1 camera is 30 Frames Per Second (NTSC).

IP Camera An IP Camera is a CCTV camera that can transmit video and audio over a TCP/IP network. An IP Camera can connect to a local network and streams its video over the network to a Network Video Recorder. IP Cameras can come with additional features including Power over Ethernet, wireless LAN connection and Mega Pixel Resolution.

IP Rating Ingress Protection Scale - 2 numbers indicating the protection level of an outside enclosure - e.g. IP68.

IR Cut Filter An IR cut filter is an extra filter inside the camera that moves behind the camera lens when it gets dark. A camera with an IR cut filter will produce very high quality images in low light conditions.

Iris An iris is a device inside a lens which opens and closes as light conditions change which adjusts the amount of light passed through.

JPEG Joint Photographic Experts Group - an image compression technique used for still images.

Lens Mount See CMount or CS Mount.

Luminance Luminance is the brightness of a video signal.

LUX Used to specify how sensitive cameras are to light (measured in lumens/sq meter). For example, a camera with a LUX Level of 0 can see in pitch black. The lower the LUX level the better the camera will see in the dark.

Mega Pixel Resolution Mega pixel resolution refers to video resolutions now achievable using IP Cameras. Unlike analogue cameras, whose resolution is usually limited to around 752 x 582 (0.4 Mega Pixels), a Mega Pixel IP Camera can achieve far greater resolutions such as 1280 x 1024 (1.3 Mega Pixels) or 1600 x 1280 (2 Mega Pixels). This increase in resolution produces far better image quality than a traditional analogue camera could ever achieve.

Motion Detection Motion detection is a recording method for digital surveillance systems. When someone walks in front of a camera, the pixels change and the DVR defines this as motion. The surveillance system will then record these images to the hard disk. This is a popular recording setup as every event recorded is actually motion driven as opposed to a static image if the system was set to record 'round-the-clock'.

MPEG Motion Picture Experts Group - a video compression technique for video images. MPEG-4 has quickly become the Digital CCTV standard recording compression format. MPEG-2 is used for DVD recording quality.

Multiplexer A Multi Screen CCTV device that allows input of 4, 9, 16 etc. cameras and provides a 'Multiplexed' (or split screen) display of those cameras.

Noise Noise is a video signal interference that usually appears as graininess or snow on the picture.

Power over Ethernet (PoE) Power over Ethernet is a method by which power is transmitted over a CAT-5/6 cable. This is often used with the installation of IP Cameras saving time/money by reducing cabling. An IP Device would need to be fitted with a PoE RJ45 port to use this functionality.

Peak to peak Peak to peak is a video signal measurement from the base of the sync pulse to the top of the white level. A full video signal should be one volt.

PTZ Pan Tilt Zoom - a camera which can be controlled via Joystick or DVR and moved up/down, left/right and zoomed in/out.

Quad Splitter A CCTV device used to display 4 cameras on one monitor.

Resolution The number of horizontal lines a system can display. Digital Resolution (e.g. 720 x 576): 720 = number of points in each row that make up the picture 576 = number of rows

RG59 A type of CCTV Coaxial cable used to transmit CCTV camera video signals to a CCTV System.

Sensitivity The sensitivity of a camera is often configured on your digital surveillance system. Motion detection based recording usually relies on the sensitivity of the cameras to trigger recording.

Telemetry Control of PTZ cameras is provided using Telemetry Control. This signal is sent down 'twisted pair' cable or along the same coaxial cable the video signal is being sent down. Typical telemetry signals are RS-485 or RS-422.

Varifocal Lens A CCTV camera lens whose focal length / viewing angle can be manually adjusted to suit the camera view required. Typical Vari Focal lens lengths are: 2.5mm-10mm, 3.5mm-8mm, 5mm-50mm

Video Splitter CCTV device that splits the video signal from a camera (or cameras) so it can be used more than once.

Zoom Lens A zoom lens is a lens which has variable focal lengths. The image can be 'zoomed' in or out whilst the view of the camera remains in focus.

Article reprinted with permission of Randy Bragg/Brownstone Companies.

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