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Closed-circuit television (CCTV) systems are a major component in modern surveillance systems.  Just like access control systems, and two-way radios, CCTV systems serve as a powerful tool in the hands of your security team.  They deter reckless and criminal behavior, gather evidence in the event of an incident, and provide a watchful eye for security teams who can’t be everywhere at all times.


As valuable as they are, understanding the ins and outs of a CCTV system can be a challenging task, especially if you’re implementing one for the first time.  If you’re looking for some extra reading material to help you through the learning curve, we’ve prepared a bit of a glossary for you.  Here is some useful CCTV-related terminology.  Knowing these terms and what they mean should make understanding your CCTV solution a lot easier.

But, if you’re looking for a more in-depth conversation on your security needs, be it on video surveillance access control, or paging and general alarm systems, you can always Contact Us directly.

Tridon’s Service Technicians and Client Support Specialists have a great deal of experience with this technology and they’re here to support you from start to finish, so don’t worry about getting lost in the weeds.  We’re here to help.

Alarm Input

Some Digital Video Recorders (a component of CCTV systems) have an input that allows them to start recording CCTV footage the moment an alarm (fire, burglar, etc.) is triggered.


Angle of View

Angle of view refers to the range of angles a CCTV camera can move through before the image or footage becomes blurry or distorted.  Cameras with a wide-angle of view are ideal for providing clear images when the subject is close up, where cameras with a narrow-angle of view are great for focusing on subjects that are far away.


Auto-Iris Lens

These types of lens can automatically adjust their opening to let in more or less light depending on the lighting conditions of the environment.  This adjustment helps surveillance cameras capture quality images and footage.


Automatic White Balance

This refers to the ability of a CCTV camera to automatically balance flushes of white light into the aperture.  The sources of this light could be something like a headlight or a flashlight.


Back Light Compensator

This feature automatically adjusts the image for bright lights or bright sunlight so that darker areas of the image (i.e. areas in shadow) can still be seen in detail.



This is a device that allows video data to be transferred by means of an unshielded twisted pair cable instead of a coaxial cable.  This is accomplished by transforming an unbalanced signal into a balanced signal.  Video transmitted by a coaxial cable can only travel a limited distance because it is subject to RF (Radio Frequency) interference.  Coax cable uses shielding to minimize interference (or noise) while baluns transform the signal from unbalanced into balanced.  Then, the signal can be carried by each wire in the twisted pair and transmitted as identical signals with oppositely polarized magnetic fields. Noise impacts each wire equally and is cancelled out when the wires combine.



This term is used to describe the rate at which data can be transferred through a network.  A higher bandwidth means a faster rate of data transfer.  The rate is commonly measured in bits per second.


BNC Connector

A bayonet-shaped connector for coaxial cables, commonly used in CCTV system installations.


Cat 5/6 Cable

CAT (category) 5 and 6 cables are used for transmitting data at high speeds.  They can transmit information at 100+ megabytes per second.  These cables are often used in voice and data applications.



The abbreviation for Closed Circuit Television.


CCTV System

A fully implemented surveillance system will include CTV cameras, cabling (coaxial or IP), a DVR or an NVR, and the requisite software.

Charge-Coupled Device

A charge-coupled device, or CCD, is a thin, light sensitive piece of equipment. It forms the imaging device of most modern CCTV cameras.  There are two types: frame transfer and interline.


CCD Image Sensor

A light-sensitive imaging device, common in many types of IP surveillance cameras.  The CCD Image Sensor enables cameras to capture video in low light conditions because of its extreme sensitivity to light.




The range of values in an image from darkest to lightest.


Day/Night Camera

These are cameras with no infrared capability that are nonetheless able to capture adequate images and footage in low light conditions.  This is possible due to the highly sensitive sensors built into the camera.


Depth of Field

This is the range across which a CCTV camera lens is able to focus.  It is measured as the distance behind an object plus the distance in front of the object when said object is in focus.

Digital Video Recorder

This is the general term given to any computer that takes video signal from a CCTV camera or system and coverts, compresses, and stores it on a hard drive.


Field of View

The maximum viewing angle seen through a CCTV camera lens.


Focal Length

The distance from the center of the camera lens and its imaging sensor.  A shorter length means a wider field of view and less magnification, whereas a longer focal length means a narrow field of view, but greater magnification.


Frames Per Second

The number of frames per second a camera can capture.


Infrared Camera

These types of surveillance cameras can record quality footage, even in complete darkness.  This is possible because of specialized infrared lights that surround the camera lens and ‘shine’ on the camera’s field of view.


Ingress Protection

This describes the level of protection an electronic device has from dust and water entering the chassis or housing.  For CCTV cameras positioned in the outdoors, a higher Ingress Protection Rating may be desirable to protect it from dust and rain.



Competing signals or electricity running through nearby cables can actually reduce signal reception and hinder quality recording.


IP Camera

These cameras are designed to record and transmit footage in common formats (like MPEG 4) and transmit them to a Network Video Recorder via ethernet cable connection.



This is the opening or aperture light passes through before it reaches the lens.  Depending on the camera model, the iris will automatically widen or narrow, depending on the amount of light in the environment.



This is a unit of illumination used to measure how effectively a camera can gather light. Surveillance cameras with lower LUX values operate better in low light conditions than those with high values.



Monochrome images will appear in black and white, with varying shades of grey in between.


Motion Detection

When applied to CCTV cameras, motion detection features allow cameras to be engaged and begin capturing footage when a certain level of motion is detected.  The activation of a surveillance camera can also trigger the activation of alarms, security lights, access control devices, and other security equipment.

When applied to DVR’s or NVR’s, motion detection features allow for the creation of pre-defined motion detection zones and speeds, as well as pre-defined responses should those parameters be met and/or exceeded.  For example, if the pre-defined area is a parking lot, and the pre-determined speed is 3 km/h, anything moving at or in excess of that speed would trigger a response – usually recording, but possibly the activation of alarms and security lights, as well.


Network Video Recorder (NVR)

This is a piece of hardware that receives the video footage being recorded on networked cameras, records it, and stores it.  Because this is an IP-accessible device, any computer on that network can access the footage, provided it has the required credentials.


Network Camera

A CCTV camera, connected to an IP network, that transmits footage to an NVR via a high speed internet connection.



On-Screen Display

A CCTV camera’s on-screen display (OSD) allows you to calibrate your camera’s settings to get the best quality images, depending on the environment in which it is installed.  Rather than being restricted to factory settings, OSD’s allow for a great deal of customization.




A surveillance camera’s full range of motion along the horizontal axis.


Power over Ethernet

This is the ability of a device to receive power over IP cabling.  This feature can simplify your data cabling layout and reduce cabling costs overall.


Tampering Alarm

This is an alert that is triggered if the viewing angle of a surveillance camera is altered or if the viewing area is blocked.


A camera’s full range of motion on the vertical axis.


Varifocal Zoom

A camera lens with a variable focal length.  As the camera zooms in or out, the focus changes.  This is different from a parfocal, or zoom, lens, which remains in focus as the focal length   changes.  Varifocal lenses offer greater flexibility because the aperture can be adjusted as necessary. The larger the aperture size, the greater the magnification and level detail a camera can capture.




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