Our jargon buster is home to our glossary of CCTV terminology. Are you unsure what some of those unusual terms and pesky acronyms actually mean when you come across them whilst installing CCTV? Here’s a quick guide to help you...
- 4K
3840 x 2160 pixels - 4K Ultra HD technology marks a shift in tech jargon where 4K refers to approximately 4,000 pixels for horizontal resolution. Previously the vertical figures were used such as 1080p so in old money 4K would be called 2160p!
- AC
Alternating Current - Used to indicate that voltage or current in a circuit that is alternating in polarity at a set frequency, often 50 or 60 Hz.
- AGC
Automatic Gain Control is a handy feature that automatically adjusts the video amplitude under various lighting conditions. If the Gain is manually set too high, it can produce a noisy image in low light conditions.
- AI
Auto Iris is a moving part of the lens that allows it to automatically open or close to vary the amount of light reaching the CCD so it can handle varyinglighting conditions better without any manual adjustment. Great feature for external cameras operating in day to night conditions.
- Amplifier
A device which increases the amplitude of a signal.
- AWB
The Automatic white balance setting controls the automatic adjustment of the light source’s colour temperature, which will adjust the picture’s colour to maintain the “best” image by keeping white objects white and so on.
- Broadcast
When a node sends out data that is intended for transmission to all other nodes on the network. The most common example is a TV station that broadcasts its programs to all TV sets tuned in to that channel.
- Baud Rate
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The rate at which data is transferred in a communication channel. Eg: 9600 Baud means a transfer speed of 9600 bits per second. Typically the baud settings of two devices must match in order to comunicate. Used as a setting between PTZ devices such as cameras and keypads to allow them to transmit to each other effectively. The lower the rate that can be selected the further the transmission distance without errors.
- BLC
Back Light Compensation allows the camera to adjust the exposure of the entire image to properly expose the subject in the foreground when a bright light source is situated behind it.
- CAT 5
(Category 5) A twisted pair cable that is capable of transmitting data at high speeds (100 megabits per second and faster). CAT5 cable is commonly used for voice and data applications. Usually comes with RJ45 connectors.
- CAT 6
Category 6 cable is a twisted pair cable for carrying signals. Performs up to 100MHz.
- CCA
(relating to cables) Copper Coated Aluminium ie: not solid copper.
- CCD
Charge Coupled Device – The main component of a CCTV camera, this converts light energy into an electrical charge which is then converted to an electrical image.
- CCFLs
Cold Cathode Fluorescent Lamps - used to backlight a screen and are much bigger and thirstier on power than LEDs.
- CCS
(relating to cables) Copper Coated Steel ie: not solid copper.
- CMOS
Works in a similar way to CCD but produces a lower quality image.
- Covert
A camera that's not openly on display.
- CRT
Cathcode Ray Tube - is a vacuum tube that contains one or more electron guns & a phosphorescent screen and is used to display images. ie. the original big box screens.
- Crosstalk
Noise generated by the interference between adjacent video, audio or data signals in a multiplexed signal.
- DDNS
Dynamic Domain Name Service/Systems essentially map internet domains to IP addresses. DDNS circumvents the need for a static IP address by offering a service that equates a static name rather than number to a device that allows a different IP address each time it is connected to.
- DC
Direct Current - Electrical current that flows in one direction.
- DNR
Digital Noise Reduction is the process of removing image noise from the video signal by applying a digital filter. A 2D filter reduces noise in low light images, a 3D filter reduces noise caused by movement giving less motion blur.
- Decibel (dB)
Logarithmic measurement of signal strength. 1/10 of a Bel. A unit of measurement for the Signal-Noise ratio. The higher the value, the better & crisper the camera’s picture & sound. Usually from 48 to 52 dB.
- DSP
Digital Signal Processing allows access to additional features within a camera like WDR, BLC, RS485. (see other terms for full explanations)
- Dual Voltage
Cameras with dual voltage options can accept either 24V AC or 12V DC power sources. Using 24V AC is a good option for longer cable runs as less volt drop occurs over the cable length.
- F Number / F Stop
Is the aperture or opening of the lens that describes the amount of light the lens lets in. The lower the number the better.
- Gain
The amplification level of an audio signal.
- IP address
An IP address (short for Internet Protocol address) is used to identify computers on the Internet. When your computer sends data, like a search on Google, it attaches your IP address. That way Google knows where to send the response.
- IR
Infra Red - Higher on the spectrum than microwave and best known for its use in short range line of sight applications such as remote control handsets.
- IR LED
Produces infrared illumination invisible to the human eye but visible to IR sensitive cameras.
- LAN
A Local Area Network is a network of computers that are in the same physical location (such as in the same building). If the computers are far apart - such as in different towns - then a Wide Area Network is used.
- LCD
Liquid Crystal Display - LCDs allow displays to be much thinner than cathode ray tube.
- LED
Light Emitting Diode - (in screens) Refers to how an LCD screen is actually back-lit with LEDs rather than CCFLs.
- Line of Sight
Where a transmission signal such as microwave has a direct path between transmitter and receiver and so has a “clear line of sight” as opposed to an obstructed one.
- MAC address
-
A Media Access Control address (MAC address) of a computer is a unique identifier assigned to network interfaces for communications at the data link layer of a network segment. It's the physical address of any device on the network.
- Mechanical IR filter
Removes unwanted IR light during the day, giving the the best possible image!
- Microwave Transmission
The transmission of information/energy using electromagnetic waves(between 1-1000mm) that occupy the middle region of the electromagnetic spectrum.
- Mifare
A contactless technology with the ability to store and transmit data a short range. Used worldwide for a variety of applications such as access control, event ticketing, top-up cards, transport tickets, smart metering and loyalty cards. See also "NFC".
- NiteDevil
A function that allows a slower shutter speed in order to let in more light to provide higher sensitivity in low light conditions.
- NFC
A contactless technology with the ability to store and transmit data a short range. Used worldwide for a variety of applications such as access control, event ticketing, top-up cards, transport tickets, smart metering and loyalty cards. See also "Mifare".
- Node
A node is anything that is connected to a network. This could be a computer, a printer or a DVR for example.
- NTSC
National Television System Committee - The video signal standard for North America and Japan.
- Multicast
In a multicast, a node sends data addressed to a special group address. Devices that wish to receive this data must register on the group.
- OPLF
Optical Low Pass Filter removes the ‘Moire’ effect created by checked patterns in an image.
- PAL
Phase Alternating Line - The video signal standard for Europe.
- Passive
A non-powered element of a system.
- Pinhole Camera
These are very small lens that can see through a small hole and used in covert applications.
- Plasma
The forerunner of flat screen technology uses small cells of electrically charged ionized gases called plasmas. Now old technology.
- Privacy masking
-
Allows you to block out areas not to record in your camera's full view, such as neighbour's windows, so that you are compliant with the Data Protection Act!
- Protocol
-
A specific set of rules or procedures relating to the format and timing of data communication between two devices. A standard procedure that two data devices must accept to be able to understand each other.
- PTZ
-
Pan, Tilt and Zoom – a term used for cameras that have the ability to rotate and angle to look at a given area. The zoom function is from the lens of the camera zooming in and out to focus on an object. Great for monitoring a wide area such as a car park.
- RCA
A common type of audio (and video) connector, often used in home entertainment systems. Also called a Phono.
- Response Time
The time it takes for a pixel to change from one shade to another say black to white. A time 8 milliseconds or less should be perfect for CCTV use without displaying any signs of a “ghosting” or lag effect.
- RF
Radio Frequency - Uses electromagnetic waves but this time between 3 kHz to 300 GHz. Widely used for broadcasting but also used for control equipment such as keyfob. Lower on the spectrum than microwave.
- Router
A router is a networking device that forwards data between computer networks and sends data to the destination node.
- RS485
A serial data standard in which data is sent typically down a pair of wires (Twisted Pair/CAT5) to send control commands to devices.
- Stereo
Audio which is made up of two channels — left and right.
- TVL
TV Lines indicate the maximum amount of individual vertical lines capable of being produced by equipment. The higher the better resolution and image quality.
- UAV
An Unmanned Aerial Vehicle is an aircraft piloted by remote control or onboard computers, such as a camera drone used to record footage from the air.
- Unicast
A transmission from one node specifically to another.
- VMD
Video Motion Detection detects changes between subsequent frames of video specifically looking for changes within defined ‘Region of Interest.’
- Wattage
This a form of power measurement so to calculate what rating of PSU you need when only have the Wattage spec of a DC item, as a rough guide simply divide the voltage by the watts eg, 12/24 = 0.5A or 500mA.
- WDR
-
Wide Dynamic Range digitally adjusts the exposure in areas of the frame to maintain optimum levels in both the dark and bright areas of an image. Balances bright and dark areas, such as when the sun is shining through a window directly towards the camera.
- WAN
A Wide Area Network connects a number of devices that can be many miles apart. For example a business may have offices in 2 cities that are connected by a WAN.
