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04:04:02
A term commonly used to define a component digital video format. The details of the format are specified in the ITU-R601 standard. The numbers 4:4:2 denote the ratio of the sampling frequencies of the luminance channel to the two colour difference channels. Therefore, there are two samples of each colour difference channel for each four luminance samples.
04:04:04
A term commonly used to define a high resolution component digital video format. The numbers 4:4:4 denote the ratio of the sampling frequencies of the luminance channel to the two colour difference channels. For every four luminance samples, there are four samples of each colour difference channel. 4:4:4 sampled signals are also available in a RGB format with equal sampling rates for each of the colour channels. A pair of coax cables are commonly used to carry the signal in according to the SMPTE 372M standard.
1080P
1080p (1920×1080 px) Known as Full HD, A set of HD High Resolution Video modes characterised by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the screen vertically; the p stands for progressive scan, i.e. non-interlaced. The term usually assumes a widescreen aspect ratio of 16:9, implying a resolution of 2.1 megapixels. It is often marketed as full HD, to contrast 1080p with 720p resolution.
1080p/24
A high definition video format which is progressively scanned with 1920 pixels and 1080 lines of data and a nominal frame rate of 24 frames per second (see also sF)
20 MHz Channel
The default bandwidth used by 2.4GHz wireless networks. When a Wi-Fi access point and all associated clients can support a 40 MHz channel, higher throughput is possible by combining channels. Whenever another access point that does not support 40 MHz channels is present, or if a legacy client is present, then all devices must use 20 MHz channels.
22KHz tone
The signal generated by a satellite receiver and relayed to an LNB to select the high local oscillator.
3D Compatible
3D compatible means that one or more of the 3D compliant formats are supported by the display or repeater device.
3D Compliant
Mandatory formats the display (sink) or repeater device must support to be HDMI 1.4a compliant are:For movie content – Frame Packing 1080p @ 23.98/24Hz. For gaming content – Frame Packing 720p @ 50/60Hz Frame Packing 720p @ 59.94/60 Hz. For broadcast content – Side-by-Side Horizontal 1080i @ 50/60Hz Side-by-Side Horizontal 1080i @ 59.94/60Hz Top-and-Bottom 720p @ 50/60Hz Top-and-Bottom 720p @ 59.94/60Hz Top-and Bottom 720p @ 23.97/24Hz
3G
3G (short for third generation) is the third generation of wireless mobile telecommunications technology.
40 MHz Channel
Newer access points and clients can use 40 MHz channels in the 2.4 GHz range to obtain higher throughputs. As long as all devices within the network can support this then the network can use 40 MHz channels, but if any legacy device is present, the entire network must fall back to using a 20 MHz channel.
4G
a mobile communications standard intended to replace 3G, allowing wireless internet access at a much higher speed.
4K
This refers to one of two resolutions. 3840 x 2160, or 4096 x 2160. It is 4 times the resolution of 1080p
4K Resolution
Initially this referred to approximately 4,000 pixels of horizontal resolution for digital cinemas where 4K =4096 x 2160 or 8.8 megapixels. 4K related to HDMI refers to 3840 x 2160 or 8.3 megapixels which is 4 times the 1920 x 1080 or 2.1 megapixel HDTV standards. 4K has 4 times the number of pixels as 1080p.
5 Megapixel
capable of resolutions up to 2560 x 1920. These cameras do have a different aspect ratio than 4MP, however. So there is a slight trade off.
720P
720p refers to an image resolution of 1280 pixels wide by 720 pixels tall. Originally a standard for HD (high-definition) television, it can refer to the resolution of video content, the recording capability of a video camera.
8 Megapixel
These are cameras that are capable of resolutions up to 3264 x 2448. This resolution is creeping up on the low end of 4K, and about to breech the high end of 2K resolutions
802.11
The IEEE committee and the set of standards maintained by the IEEE for wireless networking.
802.11a
The IEEE standard for wireless networking in the 5 GHz range. 802.11a networks can support up to 54 Mbps throughput and operate in the UNII bands.
802.11ac
The IEEE standard for wireless networking in the 5 GHz range. 802.11ac networks can support up to 1 Gbps throughput using multiple channels, 500 Mbps using a single channel, and operate in the UNII bands. It will use 80 and 160 MHz channels and MIMO to achieve higher throughput rates.
802.11b
The IEEE standard for wireless networking in the 2.4 GHz range. 802.11b networks support up to 11 Mbps throughput and operate in the ISM band.
802.11d
The IEEE standard for wireless networking that addresses the Media Access Control (MAC) layer to comply with rules in each country.
802.11e
The IEEE standard for wireless networking Quality of Service (QoS) on 802.11 a, b, and g networks.
802.11g
The IEEE standard for wireless networking in the 2.4 GHz range. 802.11g networks support up to 54 Mbps throughput and operate in the ISM band.
802.11h
The IEEE standard for wireless networking that sets the requirements for Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) so that Wi-Fi devices can coexist in the same UNII frequency ranges as other 5 GHz devices.
802.11i
The IEEE standard for wireless networking security, using AES encryption, authentication using 802.1x, and data integrity.
802.11j
The IEEE standard for wireless networking to meet the legal requirements within Japan. These include power, frequency, and operational characteristics of wireless networks.
802.11n
The IEEE standard for wireless networking that can use both the 2.4 GHz and 5 GHz ranges, with MIMO. 802.11n compatible access points and clients can support throughput rates of up to 600 Mbps, and clients are backwards compatible with older access points that can only do 802.11 a, b, or g.
802.1x
An IEEE standard for port-based authentication to the network. It can be used in Ethernet switches to restrict access to the wired network as well as in wireless access points to restrict access to the Wi-Fi network. 802.1x can use username/password or certificates to authenticate to the network. It is typically used in combination with wireless encryption schemes to provide confidentiality and integrity.
960H
960H is a resolution which offers 400% higher image quality as compare to CIF resolution. 960H resolution is 960p (horizontal) x 576p (vertical). This is also known as WD1 resolution.
A/D Converter
Analogue to Digital converter. An electronic device or circuit, which converts analogue electrical signals into digital (binary) values.
Aberration
Any inherent deficiency of a lens or optical system. Aberrations are responsible for imperfections in shape or sharpness of the image.
ABF
Auto Back Focus technology allows cameras to adjust the position of the image sensor to obtain optimal focus. This feature can also be accessed via the Web client.
AC
Alternating Current
Access Point
A device that acts as the bridge between wireless clients and the wired network. Often abbreviated as AP.
Access Points
A device that acts as the bridge between wireless clients and the wired network. Often abbreviated as AP.
ACL
An access control list is a list of IP addresses or domains that defines which network traffic is allowed.
ActiveX
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.
Ad Hoc
Ad hoc mode is a peer to peer mode of networking using WiFi networking but no access point. Ad hoc networks can include more than two devices.
Address Port
An address on a single machine that can be tied to a specific piece of software (EG Port 80 HTTP port for webserver)
Aerial
A device used to transmit or receive radio waves. An aerial can be a device that receives television or radio signals and is usually attached to a radio, television, car, building or integral to a product.
Aerials
A device used to transmit or receive radio waves. An aerial can be a device that receives television or radio signals and is usually attached to a radio, television, car, building or integral to a product.
AES
The capacity of the camera to adjust for balanced light modifications in indoor applications without the need of auto iris lenses
AF
Auto Focus : A system by which the camera lens automatically focuses on a selected part of the subject.
Afterburner
A device which translates embedded data from the video bit stream into human readable text. This text is then burnt into the on screen picture in character windows. This is usually time code data, scene, take and other post production data
AGC
Automatic Gain Control. A circuit that provides a method of keeping a signal at a constant level. Cameras use AGC to keep the video signal level high under low light conditions
AHD
Analog high definition 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
Alarm Input
Some DVRs include an input that prompts them to begin recording when the connected alarm is activated.
ALC
Automatic Level Control. This is found on auto iris lenses and is a means of ‘fine tuning’ the sensitivity of the lens. If set to ‘peak’, bright areas can show more detail and if set to ‘average’ dark areas will show more detail
Alpha channel
There is increasing application of 4:4:4:4 encoding in both electronic production and post production---- which provides full-bandwidth R', G', and B' plus the additional alpha channel to carry processing information. The alpha channel is an adaptation from computer graphics, and may contain information for linear key, for luminance and/or chroma transparency, for variable edge enhancement, and similar image-processing information.
AM
Amplitude Modulated/Modulation.
AM-N
A narrow band transmission system in which the modulating waveform is made to vary the carrier amplitude.
Amplifier
An amplifier or amp is an electronic device that can increase the power of a signal. Applications include setback, masthead, inline, distribution and headend.
Amplifiers
An amplifier or amp is an electronic device that can increase the power of a signal. Applications include setback, masthead, inline, distribution and headend.
Amplitude
The strength or magnitude of a signal
Analog Video
Composite-Video, Component-Video (YPbPr), S-Video and VGA
Analogue
Any signal that varies continuously as opposed to a digital signal that contains discrete levels representing digits 0 and 1.
Analogue Audio
audio stream encoded into the voltage amplitudes of an electromagnetic wave.
Android
A mobile operating system based on a modified version of the Linux kernel and other open source software
Angle
The field of view, relative to a standard lens in a 35mm still camera, expressed in degrees, e.g. 30°. For practical purposes, this is the area that a lens can cover, where the angle of view is determined by the focal length of the lens. A wide-angle lens has a short focal length and covers a wider angle of view than standard or telephoto lenses, which have longer focal lengths.
Angle of View
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.
ANPR
A technology that uses optical character recognition on images to read vehicle registration plates to create vehicle location data. Systems commonly use infrared lighting to allow the camera to take the picture at any time of day or night.
ANR
NVRs (Network Video Recorders) with the ANR (Automatic Network Replenishment) function can automatically store video data on the IPC (Internet Protocol Camera) storage card when the network is disconnected. After recovery of the network, the NVR automatically retrieves the video data stored on the camera.
Antenna
Antenna: An Aerial designed for the reception of Radio Frequency (RF) signals, however constructed.
AP
Abbreviation for Access Point.
AP Bridge
A bridge is a network device that interconnects two dissimilar network types. An AP can act as a bridge between the wired and wireless networks, but can also serve as a wireless connection between two wired segments.
AP Range
The distance between an AP and a client (or between two APs, see Workgroup Bridge) over which Wi-Fi transmissions can be successful. The greater the range, the greater the attenuation of a signal and the lower the overall throughput will be.
APC
Angled Physical Contact
Aperture
A means of adjusting the amount of light passing through a lens. In the CCTV environment the lens iris is the aperture control method.
Aperture Scale
The aperture scale is referred to as an F-number. The international aperture scale is: F1, F1.4, F2, F2.8, F4, F4.6, F8, F11, F16, etc.
APM
Advanced Power Management.
ARC
Audio Return Channel: If an HDTV has a built-in tuner, DVD player, or other digital content source, the Audio Return Channel allows the TV to send audio data upstream to your A/V receiver, eliminating the need for a separate audio cable in this type of configuration. Audio Return Channel-enabled TVs can either send or receive audio via the HDMI link, giving you greater flexibility in how you set up your home theater equipment and making a separate upstream audio link unnecessary.
ARP
Address Resolution Protocol. This protocol is used to associate an IP address to a hardware MAC address. A request is broadcast on the local network to discover the MAC address for an IP address.
Artefacts
The unwanted additions that are sometimes seen in compressed digital images. They are a side affect of the compression process and tend to become more prevalent as greater degrees of compression are applied.
Artifact
A defect or distortion of the image, introduced along the sequence from origination and image capture to final display.
ARTPEC
Axis Real Time Picture Encoder - A chip designed by Axis for image compression. ARTPEC supports a range of CCD and CMOS sensors, built-in functionality for sharpening, backlight compensation, noise reduction and white balance, support for multiple Motion-JPEG streams, support for MPEG-4 part 2, up to 30 frames/second from 4 simultaneous video sources and real-time compression of up to 45 Megapixels/second.
ASIC
Application Specific Integrated Circuit - A circuit designed for a specific application, as opposed to a general purpose circuit, such as a microprocessor.
Aspect Ratio
The aspect ratio of an image describes the proportional relationship between its width and its height. It is commonly expressed as two numbers separated by a colon, as in 16:9.
Aspherical Lens
A lens one or more of whose elements has a non-spherical surface. Aspherical surfaces are shaped to reduce the spherical and other aberrations.
Astra
The trade name for satellites operated by SES (Societe Europeenne des Satellites).
Astrabeam
A Blake Aerials brand reference for a group of VHF Aerials which can be used for DAB and VHF TV.
Attenuation
The loss in power of electromagnetic signals between transmission and reception points.
Attenuator
A passive device that decreases signal power.
Attenuators
A passive device that decreases signal power.
Auto Iris
A facility built into lenses to control the amount of light allowed through the lens. The auto iris compensates for differing light levels, allowing the camera picture to be consistent under varying light conditions
AVI
Audio Video Interleave - A video format that supports simultaneous playback of audio and video.
AWB
Auto White Balance. This is a facility provided on most colour cameras to adjust while levels relative to other colours
Azimuth
A compass bearing east or west of true south
Back Focus
A term used to describe the relationship of the distance of the lens to the image device. This distance is critical to maintaining the proper depth of field through changing focal lengths and varying light conditions. The correct back focus is normally achieved by adjusting the image pick-up device on the camera itself.
Backscatter
Deflection of RF through an angle of 180° and is the reflection of wave signals back to the direction from which they came
Balun
A balun is an electrical device that converts between a balanced signal and an unbalanced signal. A balun can take many forms and may include devices that also transform impedance but need not do so. Transformer baluns can also be used to connect lines of differing impedance.
Bandpass filter
A circuit that passes a restricted band of frequencies. Unwanted lower and upper frequencies are attenuated.
Bandwidth
The frequency response capability of a device or communications medium. The greater the bandwidth, the larger the capacity of the system i.e. the more information carrying ability the CCTV or network system has.
Baseband
The band of frequencies containing information after demodulation.
Baud Rate
Defines the speed of data transmission of a device in terms of bits per second, where ‘bit’ can be defined as a piece of binary information or binary digit.
Beacon
A beacon is transmitted by an AP ten times per second, and advertises the existence of the AP on a particular channel or channels. It includes information needed by clients to associate and may include the ESSID, the supported channels and data rates, and whether it is open or requires authentication.
Beamwidth
An aerial acceptance angle measured between half- power points.
BER
Bit Error Rate
Bit
A binary representation of 0 or 1. One of the quantized levels of a pixel.
Bit Rate
Bit rate is measured in bits per second. In IP video it usually refers to the bit rate from an IP camera. Controlling the bit rate controls the bandwidth needed to transfer data from the camera. The camera processor will automatically limit the maximum bit rate sent from the camera to the bit rate setting selected.
Bit Stream
The transmission of a continuous series of bits down a line.
Bitmap
A bitmap is a data file representing a rectangular grid of pixels. It defines a display space and colour for each pixel (or bit) in the display space. This type of image is known as a raster graphic. GIFs and JPEGs are examples of image file types that contain bitmaps. Because a bitmap uses this fixed raster method, it cannot easily be re-scaled without losing definition. Conversely, a vector graphic image uses geometrical shapes to represent the image, and can thus be quickly re-scaled.
Bit-rate
The speed at which bits are transmitted. This is usually expressed in bits per second. With video information, in a digitized image for example, is transferred, recorded, and reproduced through the production process at some rate (bits/s) appropriate to the nature and capabilities of the origination, the channel, and the receptor.
BLC
Back Light Compensation. A feature found on some cameras that allows it to deal with different lighting levels in the scene of view, such as looking from a dark room into a doorway. BLC enables detail to be seen in otherwise dark or shadowed areas where silhouetting would otherwise occur.
BLUETOOTH
Bluetooth is an open standard for wireless transmission of voice and data between mobile devices (PCs, handheld computers, telephones and printers).
Blu-ray
Is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs.
BNC
Invented by the named after Amphenol Engineer Carl Concelman and Bell Labs Engineer Paul Neill and was developed in the late 1940s. Used for terminating coaxial cables, the main connector in the CCTV industry
Boltzmann's constant
The relationship between the energy of a particle and its motion is related to its absolute temperature multiplied by Boltzmann's constant, which has the value of -228.6dB. This very small factor exerts a powerful influence on the effects of noise and thus on quality.
Bonjour
Also known as zero-configuration networking, Bonjour enables automatic discovery of computers, devices, and services on IP networks. Bonjour allows devices to automatically discover each other without the need to enter IP addresses or configure DNS servers. Bonjour is developed by Apple Computer Inc.
BOOTP
BOOTP is the basis for a more advanced network management protocol, the Dynamic Host Configuration Protocol (DHCP).
Bootstrap Protocol
A protocol that can automatically configure a network device (give it an IP address).
Boresight
The principle centre axis of an aerial or dish antenna.
Bouquet
A number of programmes grouped within a multiplex.
Braid
The interwoven outer conductive layer of coaxial cable made up of several bare conductors coming together to form a solid or nearly solid layer or shield. Braid is rated by percentage of coverage and by pixels per inch. Pixels per inch indicate the number of crossings of the braid in one inch of cable.
Broadband
In network engineering terms, this describes transmission methods where two or more signals share the same carrier. In more popular terminology, broadband is taken to mean high-speed data transmission.
BS
The relevant Standard currently in force as published by the British Standards Institution or the harmonized European Standard, BS EN.
BSkyB
British Sky Broadcasting.
BSS
Business Satellite Services - The band of frequencies 11.7-12.5GHz
BSSID
BSSID stands for Basic Service Set Identifier and is the MAC address of the AP.
Bullet Camera
A type of camera with a bullet like shape.
Byte
A complete set of quantized levels containing all the bits. Bytes consisting of 8 to 10 bits per sample are typical in digital video systems.
Byte
A complete set of quantized levels containing all the bits. Bytes consisting of 8 to 10 bits per sample are typical in digital video systems.
C band
The band of frequencies 3.6-4.2GHz.
C/N
Carrier to Noise Ratio, difference between modulated carrier and noise floor
C/N ratio
Carrier-to-nois - A ratio of the received carrier power to the noise power in a given bandwidth, in dBs.
C120 flange
A standard mating flange for circular Ku band waveguides.
CAI
Confederation of Aerial Industries was formed in 1978 to represent, and establish standard
CAM
Conditional Access Module. Normally fits into the PCMCIA socket of a satellite receiver, to hold a viewing card.
Camera Format
The approximate size of a camera image pickup device. This measurement is derived from the diagonal line of a chip or the diameter of the tube. Currently there are five format sizes in the CCTV industry: 1, 2/3, 1/3
Capacitance
A energy storage device that is formed wherever an insulator separates two conductors between which a voltage difference exists. Capacitance is measured in Farads.
Captive Portal
A captive portal is a process running on an access point that can redirect users who have associated to a web page so that they can agree to terms of service, purchase access or enter a password to access the WiFi.
Cascade amplifier
A line-powered amplifier that also passes the powering voltage to its input terminals.
Cassegrain
A dish with a paraboloid prime focus main reflector and a convex sub-reflector.
CAT5e
Is similar to CAT-5, the ‘e’ standing for enhanced. This cable has more ability for data transmission. Cat-5e also can be used for Gigabit Ethernet and generally has less near-end crosstalk. In new cabling system CAT5e cables are almost always used over CAT5.
CAT6
Is a most sophisticated cables, it is also comprised of four pieces of twisted pair copper wire, it has a longitudinal separator. This allows the cables to be separated from each other and, in turn, allows not only for an increased data transfer speed, but less crosstalk and double the bandwidth. CAT6 cabling is a good choice for IP Camera & NVR, especially those that are evolving and might need more options in the future. CAT-6 is perfect for 10 Gigabit Ethernet and can work at up to 250 MHz.
CAT7
A shielded cable requiring a GigaGate45 connection. Fast speeds at shorter distances, maxing out at 100 Gbps at less than 15 meter distances, and 10 Gbps at longer distances
Catenary wire
A supporting wire for an overhead coaxial cable between buildings or structures.
CATV
Community (Cable) Antenna Television.
CCD
Charge Coupled Device. The solid state device that most CCTV cameras use to gather images. Often referred to as an imager
CCIR
International Radio Consultative Committee. An international standards committee which is now known as ITU.
CCIR impairment scale
A 5 point scale of subjective analogue picture quality.
CCTV
The abbreviated form of ‘closed circuit television’.
CCTV SYSTEM
A ready to deploy package usually including IP camera, multi-channel DVR, hard drive, software and cabling
CDM
Construction, design & maintaince - Regulations concerning activities on a building site that must be complied with in certain circumstances.
CE
From 1 January 2021, the UKCA mark will start to replace the CE mark for goods sold within Great Britain. The CE mark will continue to be required for goods sold in Northern Ireland.
CE Mark
Consultants Europe. Certification Scheme for equipment compliance.
CEC
Consumer Electronics Control (CEC) is an HDMI feature designed to allow the user to command and control up-to 15 CEC-enabled devices, that are connected through HDMI, by using only one of their remote controls (for example by controlling a television set, set-top box, and DVD player using only the remote control of the TV). CEC also allows for individual CEC-enabled devices to command and control each other without user intervention.
Ceefax
The teletext service of the BBC.
CGI
Common Gateway Interface - A specification for communication between a web server and other (CGI) programs. For example, a HTML page that contains a form might use a CGI program to process the form data once it is submitted.
Channel
The frequency band over which information (data, audio TV) is relayed.
Characteristic impedance
The impedance in ohms of a device in the path of a communications signal
Chrominance
The hue and saturation of a colour. A chrominance signal carries the colour information.
CIF
An acronym for Common Intermediate Format, a set of standard video formats, defined by their resolution. CIF resolution is 352 x 288 pixels and is also known as D1 720 x 576, 2CIF, 4CIF, 960H
Cinemascope
A widescreen TV picture format, usually 16:9.
Circuit protective conductor
A cable used to earth a mains power socket.
Circular polarity
Electromagnetic waves whose electric field uniformly rotates along the signal path. Facing an incoming wave, clockwise rotation is called Right-Hand Circular (RHCP) and anti-clockwise rotation is called Left-Hand Circular Polarisation (LHCP).
Cladding
The outer coating of a glass fibre which provides a reflective surface.
Clarke belt
The circular orbital belt 35 786 Km above the equator, at which all satellites appear to be stationary.
Client/Server
Client/server describes the relationship between two computer programs in which one program, the client, makes a service request from another program, the server, which fulfils the request. Typically, multiple client programs share the services of a common server program. A web browser is a client program that requests services (the sending of web pages or files) from a web server.
Cliff effect
The effect of a digital picture suddenly blocking or freezing when the signal parameters degrade below a certain level.
Closed Caption
A system of encoding word characters into a video stream that can be decoded to allow subtitles to accompany the picture.
Cluster amplifiers
A series of filters/channel amplifiers tuned to amplify and pass a single cluster of analogue and/or digital terrestrial TV channels.
Cluster filter
A series of filters, each tuned to attenuate a single cluster of analogue and/or digital terrestrial TV channels.
CMOS
Complementary Metal Oxide Semiconductor imaging chip is a type of Active Pixel Sensor made using the CMOS semiconductor process. Extra circuitry next to each photo sensor converts the light energy to a voltage. Additional circuitry on the chip may be included to convert the voltage to digital data. CMOS cameras were originally low in quality but typically less expensive than a CCD sensor. This has been known in the market as HDIS/ HQIS/ DIS/ QIS Sensors, or flicker less camera etc
C-Mount
An industry standard for mounting a lens to a camera where a 1? x 32 thread is employed and the distance from the image plane is 17.52mm from the shoulder of the lens. A C-mount lens may be used CS-mount camera with the use of a 5mm-adapter ring.
Coaxial Cable
A cable comprised of a hollow metallic shield with a single wire running along its centre, isolated from the shield. Can transmit a wide range of frequencies with low signal loss.
Co-channel interference
Interference on a single terrestrial TV channel resulting from signals on the same TV channel.
CODEC
An acronym of Compression, Decompression. A device or piece of software that translates one file or signal format into another, ideally with an undetectable loss of quality.
COFDM
Coded Orthogonal Frequency Division Multiplex. The method of modulation used for digital terrestrial broadcasts in Britain.
Color Depth
Color depth is the number of bits used to indicate the color of a single pixel in a bitmapped image or video frame buffer. This concept is usually quantified as bits per pixel (bpp), which specifies the number of bits used. Color depth expresses how finely levels of color can be expressed.
Composite
Also called CVBS. An analog video signal carried on SCART or Phono
Composite baseband
The raw demodulator analogue output before filtering, clamping and decoding.
Composite color
Structure of a video signal in which the luminance and two band-limited color-difference signals are simultaneously present in the channel. This can be achieved by frequency-division multiplexing, quadrature modulation, etc.
Composite video
A complete video signal, including luminance, sync. and colour information but not audio or data sub-carriers.
Compression
Video must be compressed in size in order to make it manageable in the record and remote transmit functions. Typical compression standards include H.264 / M-JPEG & MPEG-4. Some DVR manufacturers use proprietary compression methods that are usually modified versions of the standards
Constellation diagram
A representation of the amplitude and phase of each bit of information in a digital symbol.
Consumer Electronic Control (CEC)
CEC is an HDMI feature designed to allow the user to command and control up-to 15 CEC-enabled devices, that are connected through HDMI, by using only one of their remote controls (for example by controlling a television set, set-top box, and DVD player using only the remote control of the TV). CEC also allows for individual CEC-enabled devices to command and control each other without user intervention.
Contention ratio
Contention ratio refers to how many people are sharing the same cable as you. Having lots of people connected at the same time can cause your contention to be really slow. The best way to understand contention ratio is thinking of it as traffic on a road
Contrast
Defines the degree of difference between the lightest and darkest parts of an image or video stream.
Control Unit
If a CCTV system has more than one camera, there must be a way to control the video signals going to recorders and monitors. There are three basic types of Video Control Unit: Multiplexer, Switch and Quad.
Cross colour
A TV picture defect that results in swirling coloured patterns.
Cross luminance
A TV picture defect that results in brightness variations and colour changes.
Cross modulation
A form of interference caused by the modulation of one or more carriers affecting that of another signal. It can be caused by non-linearity or the overloading of an amplifier, or signal imbalances.
Cross Polar Rejection
Difference in level between wanted signal and signal from opposite polarity
Cross talk
Interference between two or more video or audio baseband signals.
Cross-polarisation
Signals of the opposite polarity to those being received.
Crosstalk
Undesirable interaction between signals. Typically seen as interference on screen, which takes the form of noise, patterning or a whole host of other effects
CRT
Cathode ray tube - An evacuated glass vessel in which an electron beam produces a luminous image on a fluorescent screen.
CS-MOUNT
A relatively new industry standard for mounting a lens to a camera where a 1 X 32 thread is employed and the distance from the image plane from the shoulder of the lens is 12.52mm. A CS-mount lens may NOT be used on a C-mount camera.
CVBS
CVBS is composite video base band signal for the security camera market. This is what is considered original analog standard definition video cameras. Those Analog security cameras are not high definition and capped off at 960h 700 analog tv lines resolution.
CVi
HD-CVI (High Definition Composite Video Interface). This video format enabled analog CCTV signals to move into the high-definition range. Prior to this, it was limited to 960h
D2MAC
A satellite analogue encryption technique whereby the luminance and chrominance components of a video signal are transmitted seqentially. Used by European broadcasters.
DAB
Digital Audio Broadcasting is a digital radio standard for broadcasting digital audio radio services. DAB uses a wide-bandwidth broadcast technology and typically in the UK Band III (174–240 MHz) is used.
DAC
A facility provided on some video multiplexers and CCTV cameras, which allows the image to be ‘zoomed into’, the higher the zoom ration the more ‘blocky’ the image can become
Day/Night Camera
These are regular, non-infrared cameras with highly sensitive sensors that are capable of capturing relatively good images, even when the ambient lighting level is low.
dB
Decibel - The logarithmic ratio of voltage or power levels, used to indicate the gains or losses of signals.
dBd
dBd refers to the antenna gain with respect to a reference dipole antenna. A reference dipole antenna is defined to have 2.15 dBi of gain. So converting between dBi and dBd is as simple as adding or subtracting 2.15 according to these formulas: dBi = dBd + 2.15 / dBd = dBi - 2.15
dBi
The gain of an aerial relative to an isotropic source. This is normally 2.15dB more than the gain relative to that of a half-wave dipole.
dBm
dB power relative to a 1 milliwatt standard.
DBS
Direct Broadcast Satellite - The band of frequencies 11.7-12.5 GHz
dBw
The decibel watt or dBW is a unit for the measurement of the strength of a signal expressed in decibels relative to one watt
DC pass
The ability of a circuit element (usually a splitter, diplexer or outlet plate) to pass dc voltages – this is necessary to power a masthead amplifier or LNB, or to pass remote control signals.
DC Type Auto-Iris
Auto-iris lenses where the iris is controlled by the circuitry of the camera.
DCIF
Double Common Intermediate Format, a format of color images whose resolution is 528 x 384 pixels (PAL) or 528 x 320 pixels (NTSC)
DC-IRIS
This special type of iris is electrically controlled by the camera, to automatically regulate the amount of light allowed to enter.
DCT
Discrete Cosine Transform - An MPEG technique that converts pixel values from the time domain to the frequency domain and quantise the values to compress the data bandwidth.
DDNS
DDNS stands for dynamic DNS, or more specifically dynamic Domain Name System. It’s a service that maps internet domain names to IP addresses. DDNS is commonly used for NVR’s, DVR’s and IP Cameras when attempting to remotely connect to your system.
Declination offset
The adjustment angle of a polar mount between the polar axis and the plane of a satellite dish used to aim at the geosynchronous arc. Increases from zero with latitude away from the equator.
De-emphasis
A reduction of the higher frequency parts of a signal to neutralise the effect of pre-emphasis.
Deep Colour
Deep color is a gamut comprising a billion or more colors. The xvYCC, sRGB, and YCbCr color spaces can be used with deep color systems.
Demodulator
A device that extracts the baseband signal from a transmitted carrier wave.
Depolarisation
The twisting of the polarisation of a radio wave as it travels through the atmosphere.
Depth of Field
This is the in-focus range of the image produced by the lens. Objects in the focus area are clear. They will become less clear as they get closer to, or further away from the camera. The distance of the area of clear focus is the depth of field
Deviation
The maximum amount the carrier frequency is shifted by the modulating signal.
DHCP
Dynamic Host Configuration Protocol - DHCP is a protocol that lets network administrators automate and centrally manage the assignment of Internet Protocol (IP) addresses to network devices in a network. DHCP uses the concept of a lease or amount of time that a given IP address will be valid for a computer. The lease time can vary, depending on how long a user is likely to require the network connection at a particular location. DHCP also supports static addresses for e.g. computers running web servers, which need a permanent IP address.
Dielectric
Insulating material used to separate the conductors of a coaxial cable or the conducting circuits of a capacitor.
Dielectric plate
A device for insertion into a feedhorn to convert circularly polarised signals to a linear polarity.
Digibox
A generic name for a satellite or terrestrial digital receiver.
Digital Watermark
This technology embeds the device information onto the recorded video. Digital watermarks may be used to verify the authenticity or integrity of the video or to show the identity of its owners.
Digital Zoom
This refers to enlarging a portion of an image by adding additional pixels within the image to fill the larger area. It makes the picture area larger at the expense of video quality. The intelligence for this feature can be in a camera or a DVR. The opposite would be Optical Zoom in which a camera physically zooms into an image using all available pixels
Diplexer
A frequency-conscious device for combining or splitting signals in different frequency bands. A diplexer has a lower insertion loss than the equivalent splitter.
Dipole
Normally a single aerial element half a wavelength long with cable connections at its centre point.
Director
An element mounted on an aerial boom in front of the dipole that modifies the aerial characteristics.
Direct-Stream Digital
DSD is the trademark name used by Sony and Philips for their system of recreating audible signals which uses pulse-density modulation encoding, a technology to store audio signals on digital storage media that are used for the Super Audio CD (SACD).
Discriminator
A type of circuit used to demodulate an FM signal.
DiSEqC
Digital Satellite Equipment Control. An extension of the 22 KHz concept to provide control of multiple devices.
Dish Sharing
A signal reception system that delivers satellite signals only, via a network, to multiple outlets as if connected to own dish.
DisplayPort
DisplayPort is a digital display interface developed by the Video Electronics Standards Association (VESA). The interface is primarily used to connect a video source to a display device such as a computer monitor, though it can also be used to transmit audio, USB, and other forms of data
DMD
Differential Mode Delay
DNS
Domain Name System - DNS is used to locate and translate Internet domain names into IP (Internet Protocol) addresses. A domain name is a meaningful and easy-to-remember name for an Internet address. For example the domain name www.example.com is much easier to remember than 192.0.34.166. The translation tables for domain names are contained in Domain name servers.
DOCSIS
Data Over Cable Service Interface Specification is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable television operators to provide cable Internet access over their existing hybrid fibre-coaxial (HFC) infrastructure.
Dolby True HD
Dolby TrueHD is an advanced lossless multi-channel audio codec developed by Dolby Laboratories which is intended primarily for high-definition home-entertainment equipment such as Blu-ray Disc and HD DVD. It is the successor to the AC-3 Dolby Digital surround sound codec which was used as the audio standard for DVDs
Domain Server
Domains can also be used by organizations that wish to centralize the management of their (Windows) computers. Each user within a domain has an account that usually allows them to log in to and use any computer in the domain, although restrictions may also apply. The domain server is the server that authenticates the users on the network.
Dome Camera
A dome like shape camera that commonly used indoors. Some are designed to be infrared lighting and some are to be tamper-proof.
Down conductor
A conductive link to an earth termination to provide lightning protection.
Down-conversion
A reduction of a band of high frequencies to a lower band.
Downlink
The reception of data FROM a device.
Drip loop
A loop formed in a coaxial cable so that water will drip off instead of penetrating apparatus or a structure.
Drop-in cable
A coaxial cable linking each dwelling unit to the signal distribution network.
DSB
Double SideBand : A form of amplitude modulation where both the upper and lower sidebands (which result from modulation of the carrier by the signal) are transmitted.
DSP
Digital Signal Processing. A system supported by some CCTV cameras, which allows intelligent manipulation of the video signal in the camera for features such as backlight compensation.
DTH (Direct-to-home)
Satellite transmissions intended for reception in homes.
DTS-HD Master Audio
DTS-HD Master Audio is a lossless audio codec created by Digital Theater System. It was previously known as DTS++
DTT
Digital Terrestrial Television.
Dual Stream
It means a channel of video images passing through the video coder, and output 2 independent bit streams. The resolution, frame rate, bit rate and other parameters of output bit stream can be set independently. The output dual steam can meet different demands, for example, one for hard disk storage and the other for network transmission.
DVB
Digital Video Broadcast : Definitions of the methods of digital signal modulation.
DVB-S
Digital Video Broadcast – Satellite.
DVB-S2
Second generation (including HD) Digital Video Broadcast - Satellite.
DVB-T
Digital Video Broadcast – Terrestrial.
DVB-T2
Second generation (including HD) Digital Video Broadcast - Terrestrial.
DVD
Digital Versatile (Video) Disc
DVD-Audio
Commonly abbreviated as DVD-A is a digital format for delivering high-fidelity audio content on a DVD. DVD-Audio is not intended to be a video delivery format and is not the same as video DVDs containing concert films or music videos.
DVI
Digital Visual Interface (DVI) was developed to create an industry standard for the transfer of digital video content. The interface is designed to transmit uncompressed digital video and can be configured to support multiple modes such as DVI-D (digital only), DVI-A (analog only), or DVI-I (digital and analog). Featuring support for analog connections as well, the DVI specification provides optional compatibility with the VGA interface through a passive adapter.
DVR
An acronym for Digital Video Recorder, this is a manufacturer designed hardware platform for recording. It may have many functions like Recorder/ Multiplexer/ Remote surveillance/ Alert notification. It is a proprietary design that is unique to an individual 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
DVRs
An acronym for Digital Video Recorder, this is a manufacturer designed hardware platform for recording. It may have many functions like Recorder/ Multiplexer/ Remote surveillance/ Alert notification. It is a proprietary design that is unique to an individual 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
DWDM
Dense Wavelength Division Multiplexing
Dynamic Adjustment of Encoding Parameters
Dynamic Adjustment of Encoding Parameters In the surveillance system, for static monitoring scene, video can be recorded in low bit rate through reducing resolution, image quality, bit rate and frame rate, while changing of image scene requires higher resolution , bit rate and frame rate of video, etc to get high quality video stream. Since the above parameters can be dynamically modified, continuous images can be maintained without switching files frequently. And it does not only meet the requirement of high-quality images at critical moments, but also save the disk space and network bandwidth.
Dynamic IP
This refers to IP addresses that are automatically assigned to a network device when the user logs on to the system.
Earth bonding
The connection of a system to an earth point
Earth station
A ground-based transmitting or receiving satellite installation.
EBU
European Broadcasting Union.
EDFA
Erbium Doped Fiber Amplifier
EDID
Extended display identification data (EDID) is a data structure provided by a digital display to describe its capabilities to a video source (e.g. graphics card or set-top box). It is what enables a source device to know what kind of display it is connected to. EDID is defined by a standard published by the Video Electronics Standards Association (VESA). The EDID includes manufacturer name and serial number, product type, phosphor or filter type, timings supported by the display, display size, luminance data and (for digital displays only) pixel mapping data.
EIRP
The power of a transmitter with reference to that of a point (isotropic) source.
EIS
In conditions with slight vibrations (e.g., an electrical pole in strong winds), videos will appear fuzzy due to the vibration. EIS (Electronic Image Stabilization) can help reduce the effects of vibration in a video.
EIT
Event Information Table - Programme data relating to events occurring within a digital multiplex.
Electromagnetic
waves that are created as a result of vibrations between an electric field and a magnetic field. In other words, EM waves are composed of oscillating magnetic and electric fields.
Electromagnetic wave
The technical name for a radio wave, so called because it comprises electric and magnetic fields moving in unison.
Elevation
The vertical angle measured from the horizon up to a target satellite.
ELV
Extra low voltage - Less than 50 V rms ac or less than 120 V dc
EMC
Electromagnetic Compatibility. Engineer: Person competent to work on installation or maintenance of a signal reception system according to CAI Codes of Practice.
EMI
Electromagnetic Interference
Encoding
Converting a message to code eg when characters are stored in binary code. Often used to describe a process in which the form of an electronic signal is changed.
Encryption
The process of hiding information or keys needed to unlock scrambled signals.
Energy dispersal
A low frequency signal added to the baseband signal before modulation. Used to reduce the peak power per unit of bandwidth of an FM signal to reduce its interference potential.
EPG
Electronic Programme Guide - A compilation of all the programmes available.
ESA
European Space Agency.
ESSID
The extended service set identifier is the ‘name’ of the wireless network, and is used by all APs that provide access to the same infrastructure in an ESS. It can be advertised by APs in their beacons, or suppressed so that users must ‘know’ the ESSID before associating with an AP.
Ethernet
Ethernet is the most widely installed local area network technology. An Ethernet LAN typically uses special grades of twisted pair wires. The most commonly installed Ethernet systems are 10BASE-T and 100BASE-T10, which provide transmission speeds up to 10 Mbps and 100 Mbps respectively.
ETRAX
Ethernet Token Ring AXIS - The ETRAX chip is the cornerstone of Axis technology and the 'brain' in nearly all Axis products. A multipurpose Linux chip with integrated Ethernet networking and extremely flexible I/O options.
Eutelsat
European Telecommunications Satellite Organisation.
Extension Tubes
Various size spacers used between the camera and lens to reduce the Minimum Object Distance. Not recommended for use with zoom lenses due to the loss of tracking ability.
F/D ratio
A ratio of the focal length to the diameter of a dish.
Factory Default Settings
These are the settings that originally applied for a device when it was first delivered from the factory. If it should become necessary to reset a device to its factory default settings, this will, for many devices, completely reset any settings that were changed by the user.
FDDI
Fiber Distributed Data Interface
FEC
Forward Error Correction.
FEC
Forward Error Correction - A technique for improving the accuracy of data transmission. Excess bits are included in the outgoing data stream so that error correction can be applied by the receiver,
Feeder cable
The main coaxial cable emanating from the head end equipment and connected to one or more spur distribution cables.
Feeder Pickup
Unwanted Interference on coax cable from a local surrounding transmission.
Feedhorn
A device that collects microwave signals from the surface of a dish (located at the focal point).
Fiber Optics
A method of allowing much higher transmission bandwidth than copper cable by encoding digital information into a pulsing laser.
Fibre optics
The relay of signals on glass fibres using light waves.
Field
One half of a complete TV picture or frame. There are 50 fields per second in a PAL system.
Field Of View
The horizontal or vertical scene size at a given length from the camera to the subject.
Filter
A series of filters with adjustable attenuation, each tuned to a single terrestrial TV channel.
Filters
A device used to pass or reject a specified range of frequencies. This normally comprises one or more tuned circuits.
Firewall
A firewall works as a barrier between networks, e.g. between a Local Area Network and the Internet. The firewall ensures that only authorized users are allowed to access the one network from the other. A firewall can be software running on a computer, or it can be a standalone hardware device.
Flat screen display
A TV screen using LCD or plasma display techniques instead of a cathode ray tube.
Flylead
A plug-in lead to link together two domestic satellite or TV products.
FM
Frequency modulation - A transmission system in which the modulating waveform is made to vary the carrier frequency. (Use in the UK is for FM radio - 88-108MHz)
F-NUMBER
Indicates the brightness of the image formed by the lens, controlled by the iris. The smaller the F-number the brighter the image.
FOB
Flush Outlet Box - A TV or satellite outlet designed for flush mounting on to a flush conduit or surface pattress box.
Focal length
The distance from the reflective surface of a parabola to its focal point.
Focal Length
This is a distance from the centre of the lens to a point at which images come into focus. The CCD imager is usually set at this point to ensure image clarity. This value is what denotes the angle of view and size of the target image
FOCAL LENGTH
The distance from the center of the lens to a plane at which point a sharp image of an object viewed at an infinite position. The focal length determines the size of the image and angle of FOV seen by the camera through the lens. This is the center of the lens to the image pickup device.
Focal point
A point in front of a satellite dish to which all the reflected energy is focussed.
Folded dipole
Two half-wave dipoles connected in parallel in order to modify the centre impedance.
Footprint
The geographical area towards which a satellite downlink signal is directed. The contours indicate lines of equal signal strength.
FPS
In digital video applications, refers to the number of video images that can be captured, displayed, or recorded in a second. Also referred to as the 'frame rate' or 'refresh rate'.
Frame
One complete TV picture, composed of two fields.
Frame Rate
Frame rate is the frequency (rate) at which an imaging device produces unique consecutive images called frames. The term applies equally well to film and video cameras, computer graphics, and motion capture systems. Frame rate is most often expressed in frames per second (FPS) and is also expressed in progressive scan monitors as hertz(Hz). There are three main frame rate standards in the TV and digital cinema business: 24p, 25p, and 30p. However, there are many variations on these as well as newer emerging standards.
Frequency
The number of oscillations per second of an electrical or electromagnetic signal, expressed in cycles/sec or Hertz
Freznel zones
Circular regions of an electromagnetic wave where the signals are in the same phase
Front-to-back ratio
The ratio of the gain of an aerial in the forward direction to that in the reverse direction.
FSS
Fixed Satellite Service - The band of frequencies 10.7-11.7 GHz
F-STOP
A term used to indicate the speed of a lens. The smaller the F-number the greater amount of light passes through the lens.
FTP
Foil Twisted Pairs. Designed and constructed with a twisted pair or multiple twisted pairs of cores with an overall foil tape shield wound around the assembly.
FTTx
Fiber to the x (e.g., FTTH Fiber to the Home, FTTB Fiber to the Building)
Full-Duplex
Transmission of data in two directions simultaneously. In an audio system this would describe e.g. a telephone system. Half-duplex also provides bi-directional communication, but only in one direction at a time, as in a walkie-talkie system. See also Simplex.
Fused spur
A mains electrical power supply outlet comprising a fuse and captive mains cable (but not including a power socket).
Fusion splice
The low-loss glass fibre jointing technique using heat to join two fibres together.
G/T
Gain/noise Temperature - The figure of merit of a dish and LNB. The higher the G/T ratio, the better its reception capabilities.
Gain
The amplification of input to output power in dBs.
Galvanic isolator
An in-line device to improve lightning protection and electrical safety by providing dc isolation between different parts of a cable network. Satellites in this belt appear to be stationary.
Galvanisation
Is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting. Although galvanisation can be done with electrochemical and electrodeposition processes, the most common method in current use is hot-dip galvanization, in which steel parts are submerged in a bath of molten zinc. (see article on Galvanisation)
galvanising
to coat (metal, especially iron or steel) with zinc.
Gamma
Gamma correction regulates and modifies the total accuracy of an image for consistency.
Gang
Refers to the width of the box. A single gang box is wide enough for a single plug socket and a double gang is the same size as a double wall socket
GB
Gigabtye - A unit of data, typically used to measure large data storage or transfer capacities. 1GB = 1024MB = 1.048,576KB
Geostationary orbit
The circular orbital belt 35 786Km above the equator.
Ghosting
Multiple TV images usually caused by the reception of a signal via two different paths.
GHz
Hertz - An abbreviation for the frequency measurement of one cycle per second. One Gigahertz (abbreviated: GHz) is equal to 1,000 megahertz (MHz) or 1,000,000,000 Hz.
Gregorian
A dish with a parabolic offset main reflector and a concave sub-reflector.
Grid aerial
A series of stacked X arrays with a grid reflector, to give a high front-to-back ratio. (see JBB-4)
Ground loop
Is a condition caused when multiple earth points on a system cause Currents to flow via the screening on the cable. Causes picture disturbance, normally in the form of black bars across the picture.
Guest WiFi
Guest WiFi is a public WiFi network within a venue or public space in which users can connect. Learn more about guest WiFi.
H.264
This is also known as MPEG-4 AVC.H.264 presents superior video quality, compression adaptability, and tolerance to packet and data loss than that of H.263. It also makes use of bandwidth, producing in the capacity to run more channels over the current systems
H.265
This video compression method is an improvement over earlier formats like JPEG, M-Jpeg, MPEG-4 providing smaller average usable file sizes.
Half power beamwidth
The beamwidth angle of a transmitting antenna that produces a beam footprint contour on which the signal power is 3 dB lower than the maximum value.
Half transponder
A compromise method of broadcasting two signals through one transponder.
Harmonic
A component of a wave having a frequency an integral number of times that of the basic (fundamental) frequency eg if the fundamental frequency is f Hz, then the harmonics are 2f,3f,4f etc.
HD DVD
Short for High-Definition/Density DVD is a discontinued high-density optical disc format for storing data and high-definition video.
HDBaseT
HDBaseT, supported by The HDBaseT Alliance, is a consumer electronic (CE) connectivity technology for long-distance transmission of uncompressed high-definition video (HDMI), HD multi-channel audio, 100BaseT Ethernet, high-power (PoH – Power over HDBaseT) and RS232/IR control signals, via a 100m Cat5e/Cat6 cable with RJ45 modular connectors commonly used in Ethernet LAN
HDBaseT-Lite
A limited version of HDBaseT which supports high-definition video (HDMI), HD multi-channel audio, and RS232/IR control signals, via a 70m Cat5e/Cat6 cable.
HDCP
High-bandwidth Digital Content Protection (HDCP) is a form of digital copy protection developed by Intel Corporation to prevent copying of digital audio and video content as it travels across connections. Types of connections include DisplayPort (DP), Digital Visual Interface (DVI), and High-Definition Multimedia Interface (HDMI). The system is meant to stop HDCP-encrypted content from being played on unauthorized devices or devices which have been modified to copy HDCP content.
HDD
Hard disk drive (HDD) is the mechanism that controls the positioning, reading and writing of the hard disk, which furnishes data storage.
HDMI
High-Definition Multimedia Interface - Is a compact audio/video interface for transferring uncompressed video data and compressed/uncompressed digital audio data from an HDMI-compliant device (the source device) to a compatible digital audio device, computer monitor, video projector, or digital television. HDMI is a digital replacement for existing analog video standards.
HDSDI
High Definition Serial Digital Interface. A bit-serial digital interface for HDTV component signals operating at data rates of 1.485 Gb/s and 1.485/1.001 Gb/s. The HDSDI interface is standardised in SMPTE 292M and can be carried over coaxial and fiber optic cables.
HDTV
High Definition TV - A TV format with 1250 scanning lines to improve picture resolution and viewing quality.
HD-TVI
High Definition Transport Video Interface is an open standard for analog video transmission and is based on the original analog transmission media. The advantages of HD-TVI are as follows: 1. Further transmission distance 2. Higher video resolution 3. Reliable anti-interference performance as it carries low-frequency signal
HEAC
HDMI Ethernet Audio Control (HEAC) is a combined acronym for HEC and ARC.
Head-end equipment
The portion of an MATV system where all the signals are received and processed prior to distribution.
HEC
HDMI Ethernet Channel (HEC) provides a bidirectional Ethernet communication at 100 Mbit/s over an HDMI cable.
High-pass filter
Circuit that passes signals above a designated frequency.
HLC
In conditions with a strong light source towards the camera, there will be over-exposed areas, or high light. The HLC (High Light Compensation) function can automatically recognise and constrain the high light to make objects more distinguishable.
Home gateway
An STB interface between the delivery platform and appliances or systems throughout the home.
Horizontal polarisation
A radio wave where the electrical field is horizontal and the magnetic field is vertical.
Hotspot
An AP set up specifically to provide Internet access to users. Hotspots are popular in coffee shops, restaurants, and other publicly accessible locations, and usually do not require any authentication or offer any encryption. They provide the convenience of free Internet access to attract customers.
HPD
The Hot Plug Detect (HPD) channel senses plugging in or unplugging of an HDMI device, re-initializing the HDMI link if necessary.
HTTP
Hypertext transfer protocol - A protocol that forms the basis for communication on the web.
HTTPS
Secure Hypertext transfer protocol - A secure protocol that forms the basis for communication on the web.
Hunting
An industry term used to describe an auto-iris lenses inability to stabilize under certain light conditions.
HV
High Voltage - Over 1000 V rms ac or over 1500V dc
IF
Intermediate Frequency.
Impedance
Impedance is a measure of the overall opposition of a circuit to current, in other words: how much the circuit impedes the flow of charge. It is like resistance, but it also takes into account the effects of capacitance and inductance. Impedance is measured in ohms, typical values are 50&
Impulse noise
External interference from terrestrial sources such as thermostats, fridges etc, that can cause a DTT receiver to block or freeze.
Inclinometer
An instrument used to measure the angle of elevation to a satellite from the surface of the earth.
Inductance
The effect of a magnetic flux created by a current flowing in an electrical circuit. An inductor is normally a coil of wire mounted on a former. Inductance is measured in Henries.
Infrared
Frequency range within the spectrum of light that is invisible to the human eye. CCTVIllumination is usually designed around the infrared range of 730 – 815 nanometres
Infrared Camera
Basically, another term for night-vision cameras. Special infrared lights found around the outside of the lens emit a special kind of light that allows the camera to record clear images even when it’s fully dark.
Ingress Protection Rating
The IP Code classifies and rates the degree of protection provided against the intrusion of solid objects dust, accidental contact and water in mechanical casings. Format is two digits reference. The first digit indicates the level of protection that the enclosure provides against access to hazardous parts (e.g., electrical conductors, moving parts) and the ingress of solid foreign objects. The second digit indicates the level of protection that the enclosure provides against harmful ingress of water. For example, an electrical socket rated IP55 is dust (Ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment; complete protection against contact) and from splashing water (Water splashing against the enclosure from any direction shall have no harmful effect)
Insertion loss or through loss
The signal loss in dB caused by inserting a splitter or insert into a communications line.
Interference
Random energy and competing signals that can reduce signal reception and interfere with clear recording.
Interframe (temporal) compression
An MPEG compression technique transmitting only changes between frames.
Interlaced scanning
A technique to minimise picture flicker whilst conserving channel bandwidth. Even and odd-numbered lines are scanned in separate fields to make one complete frame.
Intermediate frequency (IF)
A middle frequency range generated after down- conversion in an LNB or receiver.
Intermodulation
A form of interference caused by the modulation of one carrier affecting that of another signal in the same frequency band. It can be caused by non-linearity or the overloading of an amplifier.
Intraframe (spatial) compression
An MPEG compression technique eliminating repitition.
Ionosphere
A layer of the atmosphere that refracts or reflects electromagnetic radio waves,
IOS
iOS (formerly iPhone OS) is a mobile operating system created and developed by Apple.
IP
Internet Protocol : A protocol that allows the internet to work, Typically standard is IPv4 but a newer standard called IPv6 is growing in popularity.
IP Address
The address of a computer on the internet displayed as a series of numbers. For example: 123.123.4.5
IP Rated
Compliant to a system of rating a piece of equipment against dust and water ingress.
IP44
Protected against solid objects over 1mm, e.g. wires & nails. Protected against water splashed from all directions, limited ingress permitted.
IP55
Protected against dust limited ingress, no harmful deposits. Protected against low pressure jets of water from all directions, limited ingress permitted.
IP66
Totally protected against dust. Protected against strong jets of water, e.g. on ships deck, limited ingress permitted.
IR Cut
IR light can distort colors in CCD and CMOS cameras. An IR filter is often used in cameras to filter out IR light during bright daylight conditions. An IR cut filter is automatically removed at low light to allow the camera to take advantage of IR light in lower light conditions. The camera usually switches to black and white operation at this time since B/W works better than color in low light. However, new Starlight Cameras have emerged as a way for Cameras to stay in color in extremely low light levels.
IRD
Integrated Receiver-Decoder.
IRIS
The hole or aperture through which light passes before reaching the lens. The iris will adjust automatically in some cameras depending on light levels.
IRS
Integrated Reception System. A signal reception system that delivers terrestrial and satellite signals to multiple outlets as if connected to own dish and aerial array.
Isotropic
Ideally, a point source that transmits signals of equal power in all directions.
ITU
International Telecommunications Union.
ITU
International Telecommunication Union
Jitter
A digital signal can suffer from variation in timing and/or displacement, and Jitter is the measure of this variation. High Jitter can severely degrade the performance of an otherwise ideal system by introducing unwanted noise at the receiver.
JPEG
The standard way of compressing images designed by the Joint Photographic Experts Group.
Ka band
A band of frequencies 20-30 GHz.
Ka band
The band of frequencies 20-30 GHz.
Kelvin
A degree of temperature in degrees Celcius or Centigrade. The Kelvin scale starts at absolute zero so Oº Celsius is equivalent to 273º Kelvin.
KHZ
Hertz - An abbreviation for the frequency measurement of one cycle per second. One kilohertz (abbreviated KHz) is equal to 1,000 hertz
Krone tool
A specialist tool for connecting telephone wires to phone sockets using the insulation displacement technique.
Ku band
The band of frequencies 10.7-18 GHz.
L band
A band of frequencies at 1.7 GHz
Ladder styles
The vertical part of a ladder to which the rungs are attached.
LAN
Local Area Network
LASER
Light Amplification by Stimulated Emission of Radiation
Laser diode
A device used in an fibre-optic transmitter that emits light waves at a single frequency.
Latitude
The measurement of a position on the surface of the earth north or south of the equator, in degrees of angle.
LED
Light Emitting Diode
Lens Format
The approximate size of a lens projected image. In most cases the lens will project a image slightly greater than the designated image size to insure the pickup device is completely covered. It is recommended that camera and lenses are the same format size. A lens a larger format size can be used on a smaller format camera, however a smaller format lens should never be used with a larger format camera.
Lens Speed
Refers to the lens aperture or its ability to transmit light. This is measured in F-stops.
Letterbox
Letterbox describes a video signal that does not completely fill the screen vertically and therefore requires bars at the top and bottom of the image.
LEVEL CONTROL
Used to set the auto-iris circuit to a video level desired by the user. Turning the level potentiometer towards the HIGH position will open the iris allowing more light to pass through the lens, towards the LOW will close the iris allowing less light to pass through the lens.
Lightning protection
A system to minimise the effects of a lightning strike.
Linear polarisation
Horizontally or vertically polarisation (as opposed to circular polarisation).
Linear Power Supply
The typical difference between a linear power supply and a switching power supply is the amount of noise, the switching power supply repeatedly turns the switch on and off at high speed. Linear power supplies produce less noise than switching power supplies and tends to be more stable and reliable.
Link budget
An overall calculation of power gains and losses from transmission to reception.
Lip-Sync
Audio to video synchronization (also known as audio video sync, audio/video sync, AV-sync, lip sync, or by the lack of it: lip sync error, lip-flap) refers to the relative timing of audio (sound) and video (image) parts during creation, post-production (mixing), transmission, reception and play-back processing. When sound and video have a timing related cause and effect, Lip-Sync can be an issue in television, videoconferencing, or film.
LNB
Low Noise Block downconverter. A low noise microwave amplifier and converter that downconverts a block or range of frequencies to an IF range.
Local oscillator
A device used to supply a stable frequency to a down- converter. The local oscillator signal is mixed with the carrier wave to change its frequency.
Loft box or StarBox
A unit containing all the devices commonly needed for the reception and distribution of terrestrial and satellite services within the home. (see proSTR range)
Log-periodic aerial
A wideband TV aerial with elements of different lengths.
Longitude
A distance in degrees east or west of the Greenwich meridian
Loop-wired network
An MATV network (no longer recommended) where the cable loops from room to room between padded outlet plates
Low pass filter
A circuit that only passes signals lower than a designated frequency.
LPCM
Linear pulse-code modulation (LPCM) is a method of encoding audio information digitally. The term also refers collectively to formats using this method of encoding.
LPS
Lightning Protection System.
LSF
Low Smoke and Fume.
LSOH (Low smoke/zero halogen)
A type of cable specified for use in public buildings to minimise the fire risk.
LTE
Long Term Evolution is the new protocol standard for all 4G phone systems and as its name suggests will be updated over time as new facilities are standardised. (see LTE FAQ)
Luminance
The brightness element of a video signal.
Luminance
The part of a TV waveform that contains the brightness information.
LUX
It measures the amount of uniform 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
LV
Low voltage - 50 – 1000 V rms ac or 120 – 1500V dc LSZH, LS0H, LSNH: Low Smoke Zero/No Halogen
MAC
A media access control address is a unique identifier assigned to network interface controllers for communications at the data link layer of a network segment. MAC addresses are used as a network address for most IEEE 802 network technologies, including Ethernet and WiFi.
Macro block
A defined group of pixels used in MPEG compression.
Magnetic north
The earth can be considered as a huge magnet having north and south magnetic poles. The line joining these poles is inclined slightly to the axis of rotation, hence true north and magnetic north do not coincide. A compass points to magnetic north.
Magnetic variation (or deviation)
The difference between true north and the north indication on a compass.
MAN
Metropolitan Area Network
Manual Iris Lens
A lens with a manual adjustment to set the iris opening (aperture) to a fixed position. This type lens is generally used in fixed lighting conditions.
MATV
Master Antenna Television System. (see proLTA41)
MATV
Master Antenna Television. A signal reception system that feeds terrestrial signals to multiple points via a network. If in multiple buildings this would be restricted to a local area.
MBPS
Megabits per second (MBPS) is a measure of data transmission speed.
MDU
Multiple dwelling unit - A group of homes, sometimes within the same building.
Megabyte
1024 Kilobytes = 1 Megabyte.
MER
Modulation error ratio - A form of S/N ratio measurement, the noise being measured within the active digital channel.
Method statement
A statement of the method to be used to carry out tasks.
MHz
Hertz - An abbreviation for the frequency measurement of one cycle per second. One Megahertz (abbreviated: MHz) is equal to 1,000 kilohertz, or 1,000,000 hertz. It can also be described as one million cycles per second.
Microwave
The frequency range from 1-30GHz and above.
MIMO
Multiple Input/Multiple Output signaling that uses several transceivers and antennae to improve throughput and range of the wireless network. Both APs and clients can use MIMO, though it is most often a feature of APs.
Mini DiSEqC
A simple version of DiSEqC with only two states.
Mixer
A device used to combine signals together.
MMF
Multimode Fiber
MOD
MINIMUM OBJECT DISTANCE (M.O.D.) - The closest distance a given lens will be able to focus upon a object. Generally the smaller the focal length the shorter the M.O.D. This distance can be altered with use of extension tubes.
Modem
Modulator/demodulator - A telephone interface used in computers and digital TV receivers
Modulation
A process by which information is added or encoded on to a carrier wave
Modulation index
The ratio of peak deviation to the highest modulating frequency.
Modulator
A device that modulates a video signal or MPEG2 transport stream onto a radio frequency carrier.
Monitor
Display equipment used to show the images detected and transmitted by security cameras.
Monochrome
A black and white TV picture
MONOCHROME
A monochrome image will appear in black and white with all the intermediary shades.
Motion Detection
If there is any motion in the configured detection area, the camera will automatically detect the event and can trigger preconfigured alarms or recording. Users can set sensitivity level, detection area, and arming schedule accordingly.
Motor feedback
Information fed back to a motorised satellite receiver concerning the orientation of the dish
MP
Megapixel; A unit used to measure the resolution of a digital image.
MPEG
This is the international standard for video compression and is named after the Motion Picture Experts Group. MPEG1 is low resolution, MPEG2 is higher resolution and MPEG4 is becoming increasingly popular in CCTV systems.
MPEG
Moving Picture Experts Group.
MPEG2
A set of digital TV compression standards.
MPEG4
A new compression standard that is object-based.
MPO
Multi Fiber Push On/Pull Off
Multi-Address Mode
Multi-address mode is an NVR (Network Video Recorder) function on networks with more than one NIC (Network Interface Controller). Each NIC works independently with separate parameter settings, which can be assigned with a different IP address in a different network. Multi-address mode can be used to establish network isolation.
Multicast
Networking term, which describes data that is sent from a single user that can be received by multiple users on the network. Commonly used for video transmission on LANs and WANs
Multicrypt
A digital scrambling system that uses a common PCMCIA interface. Several CAMs can be daisy-chained in a single receiver.
Multimode
A low-bandwidth mode of fibre-optic transmission using more than one light frequency. Used predominantly for telecommunication applications.
Multi-Path-Effect
(Ghosting) Secondary signal received at an aerial caused by a reflection.
Multiswitch
An IF switching unit to enable any satellite receiver to access either polarity or band using voltage and 22 KHz tone commands. Some versions relay terrestrial signals and allow access to multiple satellites using DiSEqC control signals.
Mutual isolation
The isolation in dBs between drop-in cables connected to the same network tee insert.
MUX
Multiplex - A digital transport stream of all the digital data carrying a number of services within a single broadcast channel.
NFC
Near field communication is a technology used with mobile devices to exchange data based on proximity, or even physical contact.
NICAM
Near Instantaneous Companded Audio Multiplex. Terrestrial transmitters broadcast sound channels using NICAM for improved sound quality in stereo.
NIT
Network Information Table - A table that describes the transport medium for services on the currently demodulated and other multiplexes.
Noise
An unwanted signal that interferes with reception of the desired information. It is usually expressed in oK or dB.
Noise figure
A ratio of the actual noise power generated at the input of an amplifier to that which would be generated in an ideal resistor. The lower the noise figure, the better the performance.
Noise temperature
A measure of the amount of thermal noise present in a system or device. The lower the noise temperature, the better the performance. Expressed in (degrees) Kelvin.
NPRM
None penetrating roof mount. Mount without any potentially harmful drilling or penetration into the roof of a building structure
NRZ
Non Return to Zero
NTSC
National Television Standards Committee. An analogue video format used as the broadcast standard for United States, Canada, Japan and several other countries. NTSC uses 525 lines per frame.
NTT
Nippon Telegraph and Telephone
NVR
An NETWORK VIDEO RECORDER records footage from an IP CCTV system
OADM
Optical Add Drop Multiplexer
OFC
Optical Fiber Communication
Offset angle
The adjustment angle of a polar mount between the polar axis and the plane of a satellite dish used to aim at the geosynchronous arc. Increases from zero with latitude away from the equator.
Offset dish
A dish with a reflector that forms only part of a paraboloid of revolution, usually excluding the pole or apex,such that a front feed causes no aperture blockage.
Offset feed
A feed that is offset from the centre of a dish antenna. This configuration does not block the dish aperture.
Ohms Law
The most fundamental relationship in the theory of electrical circuits is that relating potential difference, current and resistance, known as Ohm's Law (V=IxR).
OLT
Optical Line Terminal
OLTS
Optical Loss Test Set
OMT
OrthoMode Transducer - A waveguide splitter. The input port is a circular C120 waveguide. The two output ports can be either circular or rectangular (WR75).
ONU
Optical Network Unit
ONVIF
Acronym for Open Network Video Interface Forum. This is a growing standard for IP camera interface
Open Network
An open network is an open wireless network that permits association and authentication without requiring a passphrase, certificate, or credentials. Open networks are often called hotspots and provide free Internet access to anyone within range.
OPM
Optical Power Meter
Optical Zoom
Used to describe a method of using the lens of the camera to enhance and enlarge the image, rather than digital means. Pixelation does not come into play with this method. This is completely dependent on the camera itself. Optical Zoom allows for complete use of pixels available.
Orthogonal
At right angles to each other.
OS2
Single mode OS2 is an outdoor and loose tube optical fibre cable and is suitable for outdoor applications where the cabling process applies no stress to the optical fibres. For instance, a 250 micron coated multi-fibre, which is loose inside an enclosure or tube and/or is free to move, is classified as OS2
OSA
Optical Spectrum Analyzer
OSNR
Optical Signal to Noise Ratio
OTDR
Optical Time Domain Reflectometer
OTN
Optical Transport Network
OTS
Optical Transmission System
Output derating
The action of reducing the maximum output level of each of several amplifiers in cascade or of a single amplifier relaying several TV channels, to compensate for the overall increase in distortion levels.
P2P
Peer to Peer is a network where all users can share information equally. You share the information on each computer’s drives with all the other computers in the workgroup. The workstations (each PC) communicate directly with each other.
PAL
Phase Alteration Line. An analogue video format used as the standard for most European broadcasters and other parts of the world outside North America and Japan. PAL uses 625 lines per frame.
PAL
Phase Alternate Line - The TV broadcasting analogue format used in some parts of Europe.
PAL G
The UHF TV broadcasting standard used in Germany. The vision/sound carrier spacing is 5.5MHz
PAL I
The TV broadcasting standard used in Britain and South Africa. The vision/sound carrier spacing is 6MHz
PAN
Personal Area Network
Pan And Tilt
The camera includes a mechanism that allows it to move horizontally (panning) and vertically (tilting). These cameras also often feature a zoom function.
Panel or grid aerial
A series of stacked X arrays with a grid reflector, to give a high front-to-back ratio.
Parabola
A geometric shape that has the property of reflecting all signals parallel to its axis to a single focal point.
Parity bit
Check sum - Error correction data that is added to a data stream to make the bit values total either an odd or even number.
Passivation
Passivation is the process through which materials are protected from corrosion
Passive Splitter
A passive splitter simply divides the incoming signal between 2 (or more) outputs. A perfect two-way passive splitter would therefore provide half as much power (-3 dB) to each output. In reality, the losses will be more than that.
Path loss
The attenuation of a signal when travelling over a path between two points. Path loss varies inversely as the square of the distance travelled.
Pattress box
An adaptor used to surface-mount a flush outlet plate.
PC
Physical Contact
Phase
A measure of the relative position of a signal relative to a reference, in degrees.
Phase Modulation
A transmission system in which the modulating signal is made to vary the carrier phase.
Phono
Also called RCA. Originally designed for Audio connections but now also video (see composite) Usually colour coded yellow when video, red (Right) or white (left) when audio. Can also be used with coaxial type audio signals
PID
Programme Identity Data - A series of 4 character hexidecimal video and audio codes to distinguish between digital SCPC signals that are close together.
Pinhole Lens
Lenses used primarily in covert applications where the camera/lens must remain out of sight.
PIR
Passive Infrared. A motion detector that senses body heat to detect motion.
Pixel
Combining the words ‘picture’ and ‘element’, a pixel is the smallest area of a television picture. The higher the number of pixels, the sharper the level of detail. CCTV pictures are generally displayed in 640 x 480 pixels.
Pixel
An element of a digital picture.
Plasma display
A flat TV screen using light modulators or emitters to reproduce a TV picture.
PLC
Planar light wave circuits are either optical integrated circuits (ICs) or optical circuit boards made using the same manufacturing techniques as their electronic counterparts, using optical waveguides to route photons the same way that metal traces are used to route electrons in electronic ICs and circuit boards.
PLL
Phase-Locked Loop - A technique used to accurately lock oscillator frequencies.
PMD
Polarization Mode Dispersion
PME
Primary Multiple Earth - The main earth in a building, to which a cable distribution system must be bonded.
PoC
Power over Coaxial / Power over Cable. PoC refers to the transmission of electrical power alongside data or video signals over a single cable, eliminating the need for separate power sources at both ends. Power over Coaxial (PoC) is commonly used in CCTV and surveillance systems, where power and video signals are transmitted over a coaxial cable to reduce wiring complexity. Power over Cable (PoC) is used in AV and KVM extender systems, typically over structured cabling such as Cat5e or Cat6, to deliver power alongside video, audio, and data signals. PoC simplifies installation, reduces cable clutter, and is widely used in professional AV, security, and remote workstation applications.
PoE
Acronym for Power over Ethernet. This is a network device that provides power to a device using one of the CAT-5 cable twisted pairs. This is an installation advantage eliminating the need for a locally installed AC outlet.
POE
Power over Ethernet
POF
Plastic Optical Fiber
PoH
Power over HDBaseT (PoH) supplies up to 100W of power down the twisted pair cable which can be utilized to power a remote TV or HDBaseT receiver device.
Polar diagram
A plot of the relative gain of an aerial or dish in various directions.
Polar mount
A dish mount that allows all satellites in geostationary orbit to be received with the movement of only one axis.
Polarisation
The plane of propagation of an electromagnetic wave. There are 4 states – horizontal, vertical, left-hand circular and right-hand circular.
Polarotor
A polarity-selection device with skew adjustment.
Polykit
A kit of all the parts needed to fix a lashing bracket to a chimney.
Polythene
A waterproof material used as the outer sheath for outdoor cables.
PON
Passive Optical Network
Ports
An Ethernet port (also called a jack or socket) is an opening on computer network equipment that Ethernet cables plug into. Their purpose is to connect wired network hardware in an Ethernet LAN, metropolitan area network (MAN), or wide area network (WAN).
PPE
Personal Protective Equipment.
PPP
Point-to-Point Protocol. One of the suites of TCP/IP Protocols that are primarily used in serial point to point Communications such as null modem, dial up type PSTN and ISDN connections
PPPoE
Assigning a changeable IP address to a DVR to connect DVRs at remote places.
Pre-emphasis
A technique to increase the higher frequency components of a signal before transmission to compensate for the greater cable loss, thereby improving the signal-to-noise ratio.
Pre-Position Lenses
Pre-position lenses are specially designed lenses with extra mechanical/electrical components to allow for computer interfacing. This function allows the lens (when used with the appropriate controller) to feedback to the controller information relevant to zoom and focus propositioning allowing the controller to quickly scan to a pre-selected scene, arriving in focus at the proper zoom point without operator intervention.
Presets
Functionally that is supported by some telemetry equipmentPosition related feedback is provided by the zoom lens and pan/tilt head. Either the telemetry receiver or matrix stores this feedback whenever a position is stored as a preset. The system operator can recall preset positions very quickly with the minimum of key presses.
Prime focus dish
A parabolic dish with its focal point on its centre axis directly in front of the dish.
PSK
Phase shift keying - A transmission system in which the modulating signal is made to vary the carrier phase.
PSK
Phase-Shift Keying - A type of digital modulation.
PTP
Precision Time Protocol
PTZ
Pan Tilt Zoom 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 Tour
Facility provided by some CCTV control systems where a PTZ camera or dome can be programmed to tour between a specified series of presets. It is usually possible to program a dwell time to stay at each preset and also a speed value at which the camera will travel between presents.
PVC
PolyVinyl Chloride - A material used for the outer sheath of coaxial cables.
PVR
Personal Video Recorder
QAM
Quadrature Amplitude Modulation.
QEF
Quasi Error Free (BER)
QoS
Quality of Service enables networks to prioritize certain traffic types above others, so that things which are mission critical or latency sensitive gain preferred access to the network over things that are lower priority or can tolerate delay. This is especially useful in Wi-Fi networks using voice or video; the quality of both suffer when encountering latency. APs that offer QoS can provide more access to clients that need it than to those that do not. See 802.11d.
QPSK
Quadrature Phase Shift Keying. A modulation technique used on satellite transmissions that uses phase shifts of a carrier wave to relay 4 symbols per cycle.
Quantising
Rounding up or down to the nearest whole number.
Rack Unit
The 'U' in any server description is short for "RU" which stands for Rack Unit -- this is the standardized designation for the form factor of the server: 1U = 1.75" in height or thickness. 2U is 1.75" x2 = 3.5 inches. All rackmount servers are 19" in width.
Radian
The angle at the centre of a circle subtended by an arc equal in length to its radius. It is equivalent to 57.3o.
RAID
Redundant Array of Independent Disks is a storage technology that combines multiple disk drive components into a logical unit. A RAID setup stores data over multiple hard disk drives to provide enough redundancy so that data can be recovered if one disk fails. Data is distributed across the drives in one of several ways called RAID levels, depending on what level of redundancy and performance is required.
Rain degradation
A reduction in C/N ratio due to rainfall.
Rain outage
Loss of a Ku band signal due to absorption and thermal noise accompanying heavy rainfall.
Raster
A pattern of scanning lines on a TV screen.
RCD
Residual Current Device - An electrical safety device designed to disconnect mains power in the event of an earth current.
Real Time Video
Video recorded and displayed at 25fps with an appearance like that of real life.
Reciever
Can mean a TV, radio or set top receiver for satellite and DVB-T including video recorders, PVRs, recordable DVDs and computers.
Reed Solomon
An MPEG error correction technique using outer coding to minimise burst errors.
Reed switch
A mechanical switch operated by a rotating magnet to count the revolutions of a motor-actuator.
Reflection
The rebounding of a radio or light wave from a surface or junction of two different materials with different densities.
Reflector plate or element
The rear element of an aerial mounted behind the dipole that modifies the aerial characteristics.
Refraction
The deflection of a radio wave or light wave as it passes between two mediums of different densities.
Refresh Rate
The refresh rate (most commonly the vertical refresh rate) is the number of times in a second that display hardware draws the data. This is distinct from the measure of frame rate in that the refresh rate includes the repeated drawing of identical frames, while frame rate measures how often a video source can feed an entire frame of new data to a display. For example, most movie projectors advance from one frame to the next one 24 times each second. But each frame is illuminated two or three times before the next frame is projected using a shutter in front of its lamp. As a result, the movie projector runs at 24 frames per second, but has a 48 or 72 Hz refresh rate.
REN
Ringer equivalence number - The loading factor of a unit connected to a phone line.
Repeater
A wireless network device that receives signals and retransmits them, without providing direct access to the wired network. Repeaters are typically used to increase the range wireless networks can cover.
Resolution
A measurement of the ability of a piece of CCTV equipment or system to displayDetail. Measured in TV lines
Return Loss
Return loss is a measure of how well devices or lines are matched. A match is good if the return loss is high.
RF
Radio Frequency
RF Tilt
In RF terms this is the uneven attenuation of a broadband signal across its frequency band as it travels along a coaxial cable.
RF2
Output from older Sky satellite receivers with voltage to power Infra Red eyes
RGB
RGB covers the three primary colour signals: red, green, and blue (RGB) that together convey all necessary picture information.
RGB (red/green/blue)
The three primary colours used in colour television.
RHCP
Right-Hand Circular Polarisation.
Risk assessment
An assessment of the risks involved in carrying out a task, and how they will be minimised.
Roaming
In a wireless network with multiple APs, a client that is moving from the coverage area provided by one AP to that provided by another is roaming. It must disassociate from the first AP before it can associate to the next AP.
RoHS
Restriction of Hazardous Substances.
Router
Wireless router is an AP that also performs Internet connection sharing, and can run a DHCP service, a captive portal service,
RS232
Data transmission presentation used in many short distance serial data applications.
RS422
4 wire balanced, party line multi-drop data transmission presentation, used in manytelemetry and matrix switcher networks. One pair is used for data transmission on the otherpair for data reception.
RS485
2 wire balanced, party line multi-drop data transmission presentation, used in many telemetryand matrix switcher networks. Can run in simplex or half-duplex mode.
RSSI
RSSI is the metric for the signal strength when the user’s device is connected or seen.
S band
A band of frequencies at 2.5GHz
S/N
(Signal to noise) Ratio Measured in Decibels, this is the ratio between a useful video signal and unwanted noise. The higher the value the better.
S/N ratio
Signal to noise - A ratio in dBs of the peak voltage of the signal of interest to the root-mean-square (rms) voltage of the noise in that signal.
SATA
Acronym for Serial Advanced Technology Attachment. This is the cable that connects a PC motherboard to a disk drive or optical drive. It is a thin round cable providing serial communication. This is a newer technology than traditional parallel connections (ribbon cables). So you must know what type of drive each DVR requires
Satellite IF
The band of frequencies eminating from an LNB that are relayed via a coaxial cable to the IF input of an amplifier, multiswitch or satellite receiver.
Scalar feed
A wide-flare corrugated dish feed.
Scalar rings
A corrugated concentric surround to a prime focus feed to improve its impedance-matching characteristics.
Scanning
A moving electron beam to reproduce an entire picture as a sequence of horizontal lines.
SCART
A 21-pin socket used to connect AV equipment. The name SCART comes from Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs, (Radio and Television Receiver Manufacturers' Association)
SCPC
Single Carrier per Channel - A satellite transmission system that uses a separate carrier for each channel (compared with frequency division multiplexing which combines several channels on to a single carrier).
SD card
a proprietary non-volatile memory card format developed by the SD Card Association (SDA) for use in portable devices
SDT
Service Description Table - Data relating to the services contained within a digital multiplex.
SDU
Single Dwelling Unit, be it detached, semidetached or terraced. This would also include an individual apartment, flat or maisonette etc
SECAM
SEquential Couleur A Memoire. The French TV Standard.
SES
Societe Europeenne des Satellites. Astra is the Trademark of SES.
SFP
Small Form Factor Pluggable
Shadowmask tube
A CRT employing 3 electron guns to reproduce the red, green and blue components of a colour TV picture.
Side lobe
A parameter used to describe the ability of an aerial or dish to receive off-axis signals. The larger the side lobes, the more noise and interference that is received.
Side loss
The signal loss in dB of a network tee insert, between the input coaxial cable and the drop-in cable
Signal level meter
A frequency selective heterodyne receiver capable of tuning to the frequency band of interest, with an indicating meter showing the magnitude of the input voltage at a specific frequency.
Simulcrypt
A digital scrambling system where some of the functionality is built into the receiver itself.
Single mode
A high-bandwidth mode of fibre-optic transmission using a single light frequency.
Skew
Adjustment of an LNB to minimise reception of the unwanted polarity.
SKYQ
Sky digital set top box. The box is capable of UHD resolution and has a built-in Wi-Fi router
Slices
A group of digital macro blocks.
Slope
The uneven attenuation of a broadband signal across its frequency band as it travels along a coaxial cable
SMA
A sub-miniature RF and microwave connector that has a screw fixing to provide reliable connectivity. Available as SMA, SMA-F and SMA-RP
SMA-RP
A reverse pin SMA plug. The SMA connector is a sub-miniature RF and microwave connector that has a screw fixing to provide reliable connectivity.
Smart IR
The improved Smart IR function adjusts the IR strength to have better visibility depending on specific requirements. Smart IR is usually used to solve the problem of IR over-exposure in close shots.
SMATV
Satellite Master Antenna Television. Similar to MATV with the addition of locally modulated signals, commonly satellite programmes.
SMF
Single Mode Fiber
Snow
Video noise caused by a insufficient S/N ratio.
SOB
Surface outlet box - A TV or satellite outlet designed for surface mounting on a window frame or skirting board.
Software download
The action of upgrading the software operating system in a digital satellite receiver.
SONET
Synchronous Optical Networking
Source switching
The use of 12 V on pin 8 of a SCART connector to switch between the aerial socket and SCART inputs of a TV receiver.
Sparklies
Small black and/or white horizontal dashes in an analogue TV picture caused by an insufficient S/N ratio.
Spatial compression
Intraframe - An MPEG compression technique eliminating repitition.
SPDIF
Sony/Philips Digital Interconnect Format (S/PDIF) is a type of digital audio interconnect cable used in consumer audio equipment to output audio over reasonably short distances. The signal is transmitted over either a coaxial cable with RCA connectors or a fiber optic cable with TOSLINK connectors.
Spectrum analyser
A scanning receiver with a display that shows a plot of frequency versus amplitude of the signals being measured.
Splitter
A device used to split RF signals on a coaxial cable. These are normally passive products (not powered) so they will have a loss of signal when splitting. Some splitters will also work as a combiner working in reverse.
Splitters
A device used to split RF signals on a coaxial cable. These are normally passive products (not powered) so they will have a loss of signal when splitting. Some splitters will also work as a combiner working in reverse.
Splitters
A frequency-conscious device for combining or splitting signals in different frequency bands. A diplexer has a lower insertion loss than the equivalent splitter.
Spot beam
A circular or eliptical beam covering some defined region of the earth's surface.
Spot Filter
A neutral density filter paced at the center of one of the elements (or on an iris blade) to increase the high end of the F-stop range of the lens.
Spur cable
A coaxial cable feeding drop-in cables via tee inserts.
Spur insert
A device that transfers a specific amount of energy from a main feeder cable to one or more spur cables.
sRGB
sRGB is a standard RGB color space created cooperatively by HP and Microsoft in 1996 for use on monitors, printers, and the Internet. sRGB uses the ITU-R BT.709 primaries, the same as are used in studio monitors and HDTV and a transfer function (gamma curve) typical of CRTs.
SSID
The Service Set Identifier (SSID) is the name of the wireless network. It can be contained in the beacons sent out by APs, or it can be ‘hidden’ so that clients who wish to associate must first know the name of the network. Early security guidance was to hide the SSID of your network, but modern networking tools can detect the SSID by simply watching for legitimate client association, as SSIDs are transmitted in cleartext.
Stacking combiner
A matching device to combine the outputs of several identical aerials on to one coaxial downlead.
Standing wave
Peaks and troughs of signal on a cable due to forward and reflected signals being either in-phase or out-of- phase.
Starlight
Sony created STARVIS a back-illuminated pixel technology used in CMOS image sensors for surveillance camera applications. It featured a sensitivity of 2000 mV or more per 1 µm2 (color product, when imaging with a 706 cd/m2 light source, F5.6 in 1 s accumulation equivalent), and combined high picture quality in the visible-light and near infrared light regions within a frame.
Star-wired network
An MATV network with separate drop-in cables linking each dwelling to a multiswitch at a central node.
STB
Set-Top Box.
Sub carrier
An information-carrying wave that in turn modulates the main carrier in a communications system.
Super Audio CD
Super Audio CD (SACD) is a read-only optical disc for audio storage, introduced in 1999 and was intended to be the successor to their Compact Disc format. While the SACD format can offer more channels (e.g. surround sound), and a longer playing time than CD, research published in 2007 found no significant difference in audio quality between SACD and standard CD
S-Video
Super-video or Component video. This is a format in which a video signal is split into a luminance (brightness) component and a chrominance (color) component.
Synchronising (sync.) pulses
Pulses imposed on a video signal to keep the TV picture scanning synchronised with that of the picture source.
System
A network that feeds RF signals to multiple points. See CATV, MATV, SMATV and IRS.
Systems
A network that feeds RF signals to multiple points. See CATV, MATV, SMATV and IRS.
T568B
T568B defines the pin out, or order of connections, for wires in an RJ45 eight-pin modular connector plugs and sockets.
TAP
Tee insert - A device that transfers a specific amount of energy from the main distribution system to a secondary outlet.
Tap loss
The signal loss in dB of a network tee insert, between the input coaxial cable and the drop-in cable.
TB
Terabyte; A unit used to measure the size of the Hard Drive storage device. 1024 Gigabytes = 1 Terabyte
TCP/IP
Transmission Control Protocol/Internet Protocol. TCP/IP specifies how data is exchanged over the internet by providing end-to-end communications that identify how it should be broken into packets, addressed, transmitted, routed and received at the destination. TCP/IP requires little central management, and it is designed to make networks reliable, with the ability to recover automatically from the failure of any device on the network.
TDT
Time and Date Table - Digital data received to synchronise the IRD clock.
Telecom band
The band of frequencies 12.5-12.75 GHz
Telephone connection
The connection of an interactive digital receiver modem to a telephone line.
TELEPHOTO
Telephoto is a term used to describe lenses that have a high focal number causing the reproduced image to appear larger than human eye reproduction.
Teletext
Separate information transmitted with a TV picture signal that can be displayed on the screen in place of the normal picture. This service is called CEEFAX by the BBC and ORACLE by the ITV companies
Temporal compression
Interframe - An MPEG compression technique transmitting only changes between frames.
Terabyte
Terabtye - A unit of data, typically used to measure large data storage or transfer capacities. 1TB = 1024GB
Terminating resistor
A 75ohm matching resistor fitted across the end of an unterminated coaxial cable to prevent the creation of standing waves.
Threshold
The minimum S/N input required to allow a satellite receiver to produce a picture.
Through loss or insertion loss
The signal loss in dB caused by inserting a splitter or insert into a communications line
TIA
Telecommunications Industry Association
Time And Date Generator
A feature of CCTV that superimposes the time and date onto the video footage.
TKIP
The Temporal Key Integrity Protocol was developed as a replacement for WEP but is no longer considered secure and has been removed from 802.11 standards. See WPA.
TLS
Transport Layer Security is a protocol designed to encrypt and authenticate all kinds of network traffic at the transport layer, and is the successor to SSL. It uses certificates to exchange public keys, which are then used to encrypt session keys.
Tracking
A zoom lenses ability to remain in focus throughout the entire zoom range.
Transformer
A device to link two rf circuits together, comprising two or more coils of wire. Used to provide voltage and impedance matching and/or galvanic isolation.
Transient overvoltages
A transient over-voltage or spike is an electrical impulse of short duration but high energy that is induced onto an electrical or electronic circuit from external sources; these may be repetitive or random. Repetitive examples include switch-on or -off of electrical motors or other heavy machinery, but random events like lightning strikes or electrostatic discharge (ESD) can also induce spikes onto vulnerable circuits.
Transponder
One circuit on a satellite that receives and retransmits an uplinked signal.
Transport stream
An MPEG2 multiplex with short, fixed-length packets carrying programmes intended for general broadcast.
Tree-and-branch network
An MATV network with spur cables connected to individual drop-in cables using tee inserts.
Tree-and-bush network
An extension of the tree-and-branch MATV network concept where the with spur cables are connected via nodes to individual drop-in cables feeding each viewing location.
Triad
A group of three dots representing the red, green and blue content of a single picture element on a TV screen.
Tuned circuit
Filter - A device used to pass or reject a specified range of frequencies.
TV plug
A standard UK TV connector to specification IEC95. (Belling plug)
TVI
High Definition Transport Video Interface. It is a digital signal processing and transport technology used to transmit video in HD security cameras and DVRs. HDTV technology was developed by a company named Techpoint. They released the TVI video standard in 2014.
TVRO
A TV Receive-Only earth station designed to receive (but not transmit) satellite communications.
Twisted pair
Refers to a generic cable type, originally from the telecommunications industry where internal cable pairs are twisted together equally for the entire cable length. This type of cable is ideal for balanced data transmission.
UHF
Ultra-high frequency - The frequency spectrum 300 MHz - 3 GHz. Terrestrial UHF broadcast TV occupies the band 470 - 790 MHz.
UKCA
The UKCA marking is the product marking used for products being placed on the market in Great Britain (England, Scotland and Wales).
Unbalanced Audio
A method of transmitting audio over normal video impedance.
Universal LNB
A Ku band LNB with 9.75 / 10.6 GHz local oscillators, that uses voltage and tone switching to select polarity and band respectively.
UPC
Ultra Physical Contact
Upconverter
A converter which records an SDI signal as an HDSDI signal.
Uplink
The transmission of data TO a device
URL
Uniform Resource Locator A web address (EG blake-uk.com)
USB
A USB or universal serial bus is a standard port to which external devices can be easily connected to a computer. It is most commonly used for connecting printers, scanners and digital cameras.
UTP
An acronym for Unshielded Twisted Pair, known as network cable CAT 5 UTP or CAT 6 UTP Cable
UV
Ultraviolet radiation, that part of the Electromagnetic spectrum that causes degradation of certain materials.
Varifocal
A lens that has an adjustable focal length (Zoom)
VCA
Video Content Analysis is the capability to analyze video automatically to detect and determine temporal and spatial events. Many smart functionalities can be implemented in VCA such as intrusion detection, line crossing detection, etc.
Vector
A voltage that varies with time in a sinusoidal manner.
VESA
Video Electronics Standards Association (VESA) is an international standards body for computer graphics. VESA's initial goal was to produce a standard for 800×600 SVGA resolution video displays. Since then VESA has issued a number of standards, mostly relating to the function of video peripherals in personal computers.
VFL
Visual Fault Locator
VGA
Video Graphics Array. This is a computer video adapter which can display 16 colours with a resolution of 640x480, or 256 colours at 320x200.
VHF
30 to 300 MHz
VHF
Frequency range covering 300–3,000 MHz low-band VHF (49-108 MHz), high-band VHF (169-216 MHz), low-band UHF (450-806 MHz) and high-band UHF (900-952 MHz). VHF = "Very High Frequency". UHF = "Ultra High Frequency."
Video Type Lens
An auto-iris lens with internal circuitry for processing of the video signal which controls the iris movements.
Videocrypt
A satellite analogue encryption technique using the cut-and-rotate principle, formerly used by BSkyB.
Viterbi
An MPEG error correction technique using a variable amount of inner coding, known as FEC. This is also called convolutional error correction.
VMD
Video motion detection (VMD) is a function that allows security systems to recognise movement (as represented by a change in recorded pixels) and begin recording in response.
VOA
Variable Optical Attenuator
VPN
Virtual private network. Connecting separate LANs through the internet, while maintaining privacy
VQD
Video Quality Diagnosis is a feature that monitors the video for abnormal qualities (i.e., blurred image, abnormal brightness, and color cast). An alarm will be triggered and linked with configured response actions.
VSB
Vestigial Sideband transmission. Used for TV broadcasting. Double sideband transmission is used for low video frequencies, and single sideband transmission for higher video frequencies.
VSWR
The Voltage Standing wave Ratio. The ratio between the minimum and maximum voltage on a coaxial cable. The ideal VSWR is 1.0. Ghosting can result as the VSWR increases. It is also a measure of the reflected power to the total power at any point on the system.
WAN
Wide Area Network A network that extends over a large geographical area for the primary purpose of computer networking. (EG The Internet)
WAN
Wide Area Network
WAP
WAP can refer to the Wireless Application Protocol, or can be used to mean Wireless Access Point.
WARC
World Administrative Radio Conference.
Wave2
Technology that uses MU-MIMO and other advancements to help increase theoretical maximum wireless speeds from 3.47 Gbps to 6.93 Gbps in 802.11ac
Waveguide
Usually a hollow copper tube of such rectangular or circular dimensions that it will propagate electromagnetic waves of a given frequency. Used for relaying super high frequency waves, or microwaves.
Wavelength
The length of one complete cycle of an electromagnetic wave. Wavelength decreases as the signal frequency increases.
WDR
In conditions with very bright and dark areas, such as at an entrance door in an office building or an entranceway to an indoor parking garage or tunnel, a camera may capture over-exposed images in bright areas and under-exposed images in dark areas, which greatly affects image quality. A camera with WDR (Wide Dynamic Range) can help solve this issue. By combining images with short exposure (for bright areas) and long exposure (for dark areas) into one image, WDR technology captures both bright areas and dark areas clearly.
Web Server
If your DVR has an in-built web server, you will be able to monitor cameras over the internet.
WEEE
Waste Electrical and Electronic Equipment.
Wegener
A proprietary system for subcarrier stereo transmission. It uses discrete low level companded subcarriers.
Weighting
The correction of S/N ratio measurements to take into account such factors as bandwidth and annoyance value.
WEP
Wired Equivalent Privacy is the original encryption scheme implemented in wireless networks. Using RC4 and either a 40bit or 104 bit pre-shared key, WEP provides about the same level of privacy as using a hub does on a wired network. Easily broken, WEP is typically only deployed in home networks.
White Light
The combination of all the lights in the visible light spectrum.
White noise
Noise having a constant energy per unit bandwidth over a particular frequency band.
Widescreen
A cinemascope TV picture format, usually 16:9.
Wi-Fi
WiFi is a facility allowing computers, smartphones, or other devices to connect to the Internet or communicate with one another wirelessly within a particular area.
Window of operation
A range of minimum and maximum parameters required for the satisfactory performance of a system.
Wired Cameras
These cameras use wires to transmit video images back to the recorder. Some systems have separate wires for power and signal, some have a single wire combining the two.
Wireless
Without wires, typically a Wi-Fi RF connection
Wireless Cameras
Cameras that allow audio and video data to be transmitted back to the receiver via radio waves without the need for wires.
WPA
Wi-Fi Protected Access v2 is currently the strongest encryption protocol available to wireless networks, and is the current 802.11i standard. It uses AES encryption for data and is considered cryptographically strong. WPA2 Personal uses a PSK to establish initial authentication, but WPA2 Enterprise can use various EAP methods to ensure a strong authentication without the need for a PSK.
WPS
Wi-Fi Protected Setup makes it easier for users to add Wi-Fi clients to WPA and WPA2 protected wireless networks. It was intended to help non-technical home users deploy WPA security, but is vulnerable to a brute-force attack and should not be used. WPS can use a PSK, encryption settings transferred using a USB key, a PIN, NFC, or with a simple push button approach.
WR75 flange
A standard mating flange for rectangular Ku band waveguides.
WSD
A white space device (WSD) is a broadband device used to detect unused TV spectrum channels that do not have exclusive broadcast license requirements, such as ultra high frequency (UHF) (300–3000 MHz) and very high frequency (VHF) (30-300 MHz).
X band
The frequency band 7-8 GHz.
X-type aerial
A type of high gain TV aerial design with several elements connected at each point on the support boom, to give increased overall gain whilst minimising the overall length of the aerial.
XVR
An XVR is a DVR that can support multiple formats. HD XVR’s can support AHD, TVI, CVI, CVBS and IP simultaneously. They also have an auto detect feature so cameras from multiple formats can be recognized instantly without having to switch any settings
xvYCC
xvYCC or Extended-gamut YCC (also x.v.Color) is a color space that can be used in the video electronics of television sets to support a gamut 1.8 times as large as that of the sRGB color space.
Yagi
A common type of aerial design comprising a dipole with a rear reflector and several front director elements.
YCbCr
Is a family of color spaces used as a part of the color image pipeline in video and digital photography systems. Y' is the luma component and CB and CR are the blue-difference and red-difference chroma components.
YPrPb
A compressed bandwidth RGB signal. The video luminance (Y) is transmitted only once instead of once with each RGB channel, this requires more processing power at the receiving end, yet reducing the transfer rates by a third.
Zoom
Varying the focal length to enlarge or reduce the televised image.
Zoom Lens
A lens with the ability to change its focal length manually or through the use of a controller to cover a variety of needs.
Zoom Ratio
The ratio of the starting focal length (wide) to the ending focal length (telephoto) of a zoom lens. A 10X zoom will magnify the image at the wide end by 10 times. Examples of a 10X zoom lenses; 8mm~80mm, 12mm~120mm.