Homeshield Glossary of CCTV terms

 AGC allows a camera to maintain consistent images in differing light conditions. In England and some areas of the UK we have a varied and seasonal climate so light varies at different times of the day and year.  AGC ensures a consistent camera image.

 On a normal still camera to take a picture you would adjust the shutter speed which will vary the amount of light that enters the camera. In bright light you will need a fast shutter, in low light you will require a slower shutter.    

With a CCTV camera  you have an electronic equivalent.  The longer it remains open the more light that enters but also the more blurred the image.

  ActiveX is a standard that enables software components to interact with one another in a networked environment, regardless of the language(s) used to create them. Web browsers may come into contact with ActiveX controls, ActiveX documents, and ActiveX scripts. ActiveX controls are often downloaded and installed automatically as required.

 Analog high definition is a closed-circuit television video surveillance standard that uses coax cable to transmit HD video from security cameras to DVRs. AHD supports 720p, 1080p(2MP), 4MP, 5MP and 8MP HD video resolutions.

An Auto Iris lens will adjust the shutter automatically to allow the right amount of light to fall on the imaging device. 

In CCTV, analog refers to a Camera Video Format. This refers to systems and components that use the Video standard NTSC/PAL composite video formats. New technology has allowed Analog to attain high resolutions which are reffered to as HD Analog or HDCCTV. Current HD Resolutions are up to 8MP as of 2019.

The angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view, or FOV. Angle of view is generally describe in degrees such as 90°, 75°, etc. and can be determined in width and height of view.

AI for CCTV video surveillance utilizes  software  that will analyze the images from security Cameras in order to recognize humans, vehicles or objects. Common AI functions include “Face Detection”, “Left Baggage Detection” and “Line Crossing” .

This refers to the ratio of the vertical to the horizontal image size. This is usually 4:3 for analog video. A widescreen monitor typically has a 16:9 video format option.

Back light compensation. This clever feature helps even out an image. If you Imagine that you were standing in front of a window having a photo taken. The camera would either choose you as the subject and the outside of the window would appear pale and washed out, or it would choose the outside as the subject and you would be too dark. Back light compensation just helps avoid this and evens the picture out.

This is a device we often use at Homeshield when installing cctv systems which  allows video to travel over a twisted pair (Cat 5) wire rather than coax (RG 59) cable. 

 This is the standard connector type we use in most CCTV installations. It provides an easy snap-on connection for a coax cable. 

 Some CCTV companies quote CDS as helping cameras see in low light levels. It’s a bit of a cheat really and just the photo-cell which turns the Infra Red lights on. Every camera with Infra Red lighting has a Cadmium Sulphide sensor which is just a light switch and nothing to do with the camera CCD sensor.

 Short for Digital Video Recorder, this is a hardware platform for recording. It may have many functions unique to each manufacturer. DVR’s are commonly used in HD CCTV and generally will have BNC Inputs. DVR’s range from 4 Channel to 32 Channel. New versions of HD DVR’s which support multiple HD Formats are called XVR’s 

Many of our CCTV systems come with cameras that have built in infra-red lighting. At low light levels the small led's will switch on and the camera switches to black and white mode. You can't actually see infra-red lighting with the human eye although you will notice a slight red glow if you look at the led's on the camera. The camera picks up the infra-red light as it hits a surface and is reflected back which is why it can see in the dark.

 This is a mechanical device which slides an infra-red filter in front of the camera lens during the day to improve colour rendition. At night when the camera switches to black and white and the infra-red led's turn on the filter slides away. We don't usually like  I/R cut filters as they can fail either through age or environmental extremes.

 Digital signal processing is the general term used to describe improvement of the initial image. It also incorporates additional features such as backlight compensation, motion detection and so on. This takes place on microchips which are separate from the CCD or CMOS sensor. Also referred to as the Chip set.

This refers to how well the CCTV security camera performs to dust and water penetration. It is quoted as a double digit number. The first number relates to dust protection and ranges from 0 to 6 with 0 offering no protection, 6 offering total protection. The second number refers to the level of water protection and ranges from 0, no protection, to 8, total protection from long periods under water under pressure. The numbers that should interest you are 5 – protection against low pressure jets of water sprayed from all directions, 6 – protection against strong jets of water, suitable for use on a ship's deck, 7 – protection against temporary immersion up to 1m for periods of up to 30 minutes. In practice anything over IP65 is suitable for outside use. If you live in a lighthouse then you might want to up the ante to IP66 or even IP 67. Our CCTV cameras have a rating of IP-67.

There is no worldwide standard method of broadcasting television images. North America, half of South America and most of Asia use a format known as NTSC. In the UK we use a system known as PAL. There is a third  broadcasting system called SECAM used in France however we wont touch on that here.

If your purchasing equipment make absolutely sure that it is compatible with your television system. NTSC and PAL do not work together.  All our products are sold as PAL versions so you will have no problems in the UK

This refers to one of two resolutions. 3840 x 2160, or 4096 x 2160. It is 4 times the resolution of 1080p. This will also allow much higher zoom rates on stills taken from any video clips.

This is the measure of the amount of light that falls on one square meter. Security camera specs use the lux to indicate how much light they require to operate, with lower lux levels indicating a camera as more effective in lower ambient light conditions.

 This is a Technology to auto-adjust the intensity of built in infrared LEDs to compensate for objects within close proximity to the camera lens.

This stands for Pan Tilt Zoom which is a device that can be remotely controlled to provide both vertical and horizontal movement for a camera, with zoom. This is a movable mechanical base for a camera. PTZ cameras are used to actively search a wide area up to 360 degrees and zoom in to a point of interest

This is the ability of a camera to mask parts of its normal viewing area to prevent the operator from viewing certain areas. This can be in fixed cameras or in PTZ cameras.