CCTV Glossary of Terms

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Access Card

Access Code

Access Point

ActiveX

AGC Automatic Gain Control

Alarm Input

Algorithms

Ambient Light Level

Analog Signal

Angle of View

Annunciator

Aperture

Address Resolution Protocol

Aspect Ratio

Aspherical Lens

Attenuation

Automatic Gain Control (AGC)

Auto Iris (AI)

Auto Iris Lens

Automatic White Balance

Back Focus

Backlash

Balun

Bandwidth

Biometrics

Back Light Compensation BLC

BNC Connector

Broadband

Bullet Camera

Burn

Cable Tray

CCD Charge Coupled Device

CCTV (Closed Circuit Television)

CIF (Common Intermediate Format)Resolution

CMOS

C-Mount

This is a specific type of camera, as well as its corresponding lens mount. The C-mount lens is found in older versions of security cameras, and has a flange back distance of 17.5mm. In order to achieve a focused image, a 5mm ring must be inserted between the camera and lens.

Coaxial Cable

A cable with a central conductor that’s surrounded by a shield sharing its same axis is called a coaxial cable. It’s used primarily for carrying high frequency or broadband signals. RG59 video coaxial cable is used for digital video recorder (DVR) installations.

CODEC

Compression

Composite Video

This type of video is a combination of different source video signals, usually YUV, field, line, blanking pedestal, color sync, and field equalizing pulses. The end result is one composite signal, allowing it to be modulated onto a RF carrier.

Concave

A concave optical lens has an inward curving surface, causing incoming light to diverge.

Convex

A convex lens curves outwards, and is sometimes known as converging. Light that passes through converges to a focal point.

Covert

A CCTV surveillance system that uses hidden cameras and lenses is considered to be covert.

Crosstalk

In a multiplex signal, video, audio, or data channels with adjacent signal frequencies can create interference. This interference produces a noise known as crosstalk.

CRT (Cathode Ray Tube)

The CRT is a tube found in most televisions, monitors, and video monitors. Once heated, it creates images by emitting a beam of electrons that hit a phosphor-coated surface. The glow of the surface is dependent on the beam’s intensity. Each CRT uses deflection circuitry to control the beam’s movement.

CS Mount

CS mount lenses offer a longer focal distance than their C mount predecessors. They have a flange back distance of 12.5mm. Because they are more practical for compact cameras, CS mounts are used in most modern cameras. A 5mm spacer ring (known as a C ring) enables CS cameras to also use a C mount lens.

D1 Resolution

Day/Night Camera

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

dB (Decibel)

A decibel is a logarithmic unit that measures the loudness, power, or strength of a signal.

DC (Direct Current)

DC differs from AC (alternating current) in that electricity always flows thorough it in the same direction. A pair of wires has one positive wire and one negative. Many security cameras are 12 Volt DC, although some can operate at different voltages.

DC Type Lens

An auto-iris lens with internal circuit that receives voltage and a video signal from the camera to adjust the iris.

DD (Direct Drive)

This uses a gearless drive mechanism, making it less prone to mechanical failure. PTZ security cameras will often use them for pan, tilt, and zooming.

Default Gateway

In order to send data or video between networks, the IP Address of the Router is required. This address is known as the Default Gateway.

De-multiplexing

This refers to the procedure of separating different channels of video, audio, or data that were multiplexed at the source.

Depth of Field

DHCP (Dynamic Host Configuration Protocol)

A DHCP refers to the protocol used by a host computer to obtain an IP address so that it can communicate with other host computers. These addresses are usually dynamic, meaning they change periodically, so a connection cannot be obtained (or maintained) over the open Internet. Use of both static IP addresses and dynamic DNS helps establish a consistent connection.

Digital Signal

A sequence of binary bits that represent ones and zeros makes up a digital signal.

Digital Signal Process

A sophisticated chip in the camera that will enhance and compress the image before it is either converted to analog and transported or remains digital.

Distribution Amplifier

This device amplifies and distributes an audio or video signal to multiple outputs, such as several video monitors or recording devices. This device allows the maintenance of the original signal’s output impedance to avoid mismatches which could reduce the power required to properly drive the signal’s end point.

Duplex (Multiplexer)

A multiplexer that allows the user to look at multi-screen images while performing time multiplex recording.

DivX

DivXNetworks created DivX, a MPEG-4 digital video technology. Among its benefits is compression technology, which allows DivX equipped network cameras to store a month of video on a 20’gigabyte hard drive.

DNS (Domain Name Service)

DNS is the system that matches server IP addresses to web site domain names.

Dome Camera

A common indoor security camera, dome cameras are mounted on the ceiling. Their two main advantages are a more appealing visual appearance and being easily movable. Their drawback is a lack of usefulness during low light situations (therefore not effective when the lights are off).

DSL (Digital Subscriber Line)

DSL is a digital telecommunications protocol that allows existing copper phone lines to be used for high-speed transfer of data between home and business end-users. xDSL refers to the various types of Digital Subscriber Lines which include: ADSL (Asymmetric DSL), SDSL (Single-line DSL), HDSL (High-data-rate DSL) and VDSL (Very-high-data-rate DSL). In theory, ADSL (the most common of these types), allows for download speeds of up to 9 Mbps and upload speeds of up to 640 Kbps. In reality, commercial performance is normally up to 1.544 Mbps download and 128 Kbps upload.

DSP (Digital Signal Processing)

These chips can compress video independent of the CPU, which avoids the need to draw processing power from the CPU, allowing it to focus on other applications and computing tasks.

DTMF (Dual Tone Multi-Frequency)

The scientific term for the Touch Tone signal used on telephones, it is the existing standard for the use of twisted wire pairs to send signals. Some PTZ cameras use DTMF signals in the transferring of telemetry information to the camera. This allows users to move the camera by dialing the number for that camera and then pressing buttons on their phone.

Duplex

A type of multiplexer that allows you to simultaneously record images to tape and display live multiple-picture (or single picture) screen images of security cameras. Another capability that is provided is the ability to record images on one VCR while at the same time playing back previously recorded images on a second VCR. Compare with a simplex multiplexer which provides less features and capabilities.

DVR (Digital Video Recorder)

This device transforms analog video signals from security cameras into digital format, suitable for storage on a hard drive. It also helps the user manage the stored video files, as well as providing motion detection settings and PTZ security camera control. DVRs can often be remotely accessed over the Internet.

Dwell Time

The time a multiplexer or DVR stays on an individual camera before moving onto the next one in the sequence is known as dwell time.

Dynamic IP address

This is the rotation of IP addresses such that every time a user logs onto the Internet, their IP address changes. This is done for Internet security purposes, either by the user or by their ISP. This process can interfere with the use of networked devices such as Network IP Cameras because they normally require a static IP address to function properly.

EI (Electronic Iris)

Automatically changes a CCD camera’s shutter to mimic Auto Iris control, allowing fixed or manual iris lenses to be used in a range of areas that used to require an auto iris lens.

EIA (Electronic Industries Association)

EIA is both an electronics trade organization that develops industry standards and a term associated with serial communications applicable to digital video recorders.

Electronic Shuttering

This term applies to video cameras that compensate for moderate indoor changes in light without use of auto iris lenses.

E-mail notification

This is a feature of certain motion detecting Network IP Cameras. When activity is detected, they can email authorized users images or video.

Embedded operating system

Cameras with this can also operate as computers. With an OS like Linux installed, they can perform other tasks such as sending images to a web site via FTP, email notification, and being simultaneously accessible by multiple users.

EMI (Electro Magnetic Interference)

If improperly shielded, most electronic equipment causes EMI. The FCC sets the standards for electronic equipment shielding.

Ethernet

Ethernet can send information either wirelessly (known as WiFi) or, more commonly, over wires. It runs at 10mbps, and all terminals connect to a single common bus (sometimes called a highway). It serves as the IEEE (Institute of Electrical and Electronics Engineers) 802.3 standard, which ensures that networks adhere to a particular set of technical standards. A new type, known as Fast Ethernet, or 100Base-T, runs at 100Mbps, and the newest type, Gigabit Ethernet, runs at 1gigabit per second.

Event recorder

This type of recorder is kept in pause mode, and only records if activated by an alarm.

Extruded aluminum

This type of aluminum is used to construct housings for CCTV (closed circuit television) applications and provides the added benefits of increased strength, durability and resistance to harsher environmental conditions as compared to plastics.

Fast Lens

FCC (Federal Communications Commission)

This United States commission regulates communications by setting rates, controlling broadcast licensing, and testing electronic equipment to RF (radio frequency) transmission and related standards.

Fence disturbance sensor

The perimeter fence around a site may have one of these installed around it for intrusion detection. These sensors can be interfaced with a CCTV switcher so that specific cameras are activated in an area where the disturbance is detected.

Fixed Iris

Fiber Optics

These high-speed computer-networking cables transmit data using light instead of copper.

Field

Field of View

Firewall

A firewall is a software or hardware application installed on a home or office computer that is intended to prevent unauthorized users from accessing that computer. With hacking and network intrusions on the rise, they are becoming essential in protecting private information. Four popular types of firewall are packet filtering, application gateways, circuit-level gateways, and proxy servers. Although they can be difficult to configure correctly, they are a critical component to protect unauthorized access and hacking of IP based surveillance systems that are LAN based.

Flange back

This refers to the distance from lens flange (the beginning of the lens mount) to the focal plane. The flange back measurement for C-mount lenses is 17.52mm, while CS-mount is 12.5mm.

Flickerless Mode

Setting in cameras that will allow the camera to work with 50hz fluorescent lights to keep the camera from pulsing

F-stop

Focal Length

Footcandle

It is the light intensity (illumination) of a surface one foot distant from a source of one candela. It is equal to one lumen per square foot. (1FC = 1 lm ft2). The footcandle is the unit used to measure incident light.

Frames Per Second FPS

Frame

Frames Rate

FTP (File Transfer Protocol)

FTP is a client/server protocol used for the exchange of data between computers. Network cameras with an embedded operating system use FTP to send camera images to an authorized user’s computer or web site.

Gamma correction

This refers to an automated correction installed into surveillance cameras that adjusts for the brightness characteristic of the monitor, with the range being from .45 to 1.

Gen-lock

The use of composite video, composite sync, or vertical or horizontal sync to synchronize one or more cameras is known as Gen-lock.

Ghost

Also known as ghosting, this is when an image moved across a computer screen leaves a brief lingering shadow of itself where it had just been, creating a kind of smear or blur. Lower quality computer screens often leave ghosts. Technically, the secondary visual signal has been created and received either earlier or later than the primary signal itself.

Ground Loop

This type of picture interference is caused when the ends of a video cable have differing ground potential, causing an AC current. This is either a black shadow bar onscreen or a tearing in the top corner of the picture results. The use of ground loop insulators prevents this problem.

GUI (Graphical User Interface)

Pronounced ‘gooey’, this is the interface between the computer and the matrix switcher. Active areas of the computer screen are programmable, feature menus, icons, are clickable, and able to activate devices such as VCRs and matrix switchers. Essentially, the GUI makes the CCTV system easier to use.

H.264 Compression

Hertz

A Hertz (Hz) is the unit used to measure frequency, with 1 Hz equal to 1 cycle per second.

Horizontal hum bars

Sometimes called Venetian blinds because they are horizontal bars (either black or white) that extend across an entire picture. They’re either moving or stationary, and are the result of roughly a 60 Hz interfering frequency (usually from a 60 Hz AC power source).

Horizontal resolution

This measures the maximum amount of individual picture elements recognizable in a single scanning line.

HTML (HyperText Markup Language)

HTML is the language used in the creation of WWW pages, with use of hyperlinks and markup for text formatting.

HTTP (HyperText Transfer Protocol)

This is the protocol utilized to transmit and request information from WWW servers to browsers, either online or over networks.

Hub

Networks rely on devices called hubs to connect multiple computers together into a LAN. Standard hubs share the bandwidth across all ports (so an eight port 100 Mps hub allocates this 100 Mps among the eight ports), while switching hubs are able to give each individual port a dedicated bandwidth amount (so these same eight ports could conceivably each receive a full 100 Mps of bandwidth on a switching hub).

IFrame

Image intensifier

This device is used to intensify low-level lighting conditions via light sensitive phosphor screens, and is specifically used to improve the performance of surveillance cameras in low light conditions.

Image Size see CCTV Resolution

Images Per Second IPS

Impedance

Measured in ohms, impedance describes the input and output characteristic of an electrical system. For the best signal quality, both input and output impedances should be equal, with CCTV systems having 75-ohm impedance throughout.

Index of refraction

This ratio measures the angle of incidence to the angle of refraction of light, with a denser medium bending more light and having a higher index of refraction.

Infrared Camera

Infrared detector

These cameras are well suited for surveillance of low light areas or areas with no light at all. Infrared LEDs surround the lens and shine infrared light, illuminating the scene. They usually have a fixed focal length lens, and present b/w images during low light (though some offer color in the day and b/w at night).

Infrared Illuminator

Infrared radiation

Injection molded plastic

Smoked or tinted plastic (but still translucent) is melted into a liquid from pellets and injected into a “dome-shaped” mold to construct security camera dome housings.

Insertion loss

If the inclusion of an electronic device into a line diminishes the signal’s strength, it’s called insertion loss.

Interlaced

This refers to a type of display where the electron beams alternate between scanning the even numbered lines and then the odd numbered lines, resulting in the two vertical scans on the screen, with the field (each set of lines) being updates 60 times a second, and with the frame (both fields) updated 30 times a second.

Interleaving

Some alarms and security systems use the process of interleaving to add extra frames from alarmed cameras to a time multiplexed sequence while the alarm is activated. This prioritizes the view from alarmed cameras in the sequence of camera views.

IP (Internet Protocol)

This is the protocol used to route a packet of data from source to destination over the Internet. Every computer on the Internet has a different IP address that identifies it from other computers.

IP address

This is a numeric address that is then translated into a domain name by the DNS (domain name server). When we type in a website’s name, the computer translates this into its IP address, which is a unique 32-bit number. The TCP/IP protocol then uses it for routing the data packets to their destinations. Each host has a unique IP address.

IP Camera (or Network Camera)

This signal from an IP camera is delivered over an IP network. The camera digitizes the images, compresses them, and then sends them over the network (if this sounds similar to a webcam, that’s because there is digital webcam technology contained within a network camera). But a typical IP network camera is much more advanced as compared to a consumer web camera which needs to be attached to a computer to operate. IP enabled security cameras usually offer a browser interface so that the user can operate and view the video remotely over the Internet. A DVR system is often comprised of an IP camera and a NVR.

IP Ratings

IR Cut Filter

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

IRE

Units on the scale defined by the Institue of Radio Engineers. IRE 40 would be the amount of useable video in a low light situation. IRE 100 would be fully useable video. It is generally stated on a camera spec sheet next to the LUX level.

ISDN (Integrated Services Digital Network)

ISDNs are digital telecommunications lines that transmit voice and digital network services. Many telephone companies provide them, due to their superior reliability and speed (up to 128K) over analog modems. The ISDN standard improves compatibility for the integrated digital transmission of voice, video, and data over normal copper telephone wires, which allows for better quality and speeds. There are two primary types of ISDN: BRI (Basic Rate Interface) and PRI (Primary Rate Interface). PRI is faster, with speeds on par with T-1 circuits.

ITU (International Telecommunications Union)

Joystick

PTZ controllers utilize this stick as a control device for pan and tilt movement of a PTZ security camera’s pan and tilt head.

JPEG (Joint Photographic Experts Group)

LAN (Local Area Network)

Latency

LED (Light Emitting Device)

Level control

Light sensor

Limit switch

Linux

Loss Prevention

Lumen

Lux

Manual Iris

Matrix switcher

Megapixel Cameras

Megapixel Resolution

Mimic panel

Minimum scene illumination

MJPEG (Motion JPEG)

MMS (Microsoft Media Services)

MOD (Minimum Object Distance)

Monochrome

Motion Detectors

Motion Detection

MPEG (Moving Picture Experts Group)

MPEG4

MTBF (Mean Time Between Failures)

Multicast (or Multicasting)

Multiplexer

Nema Ratings

Network Camera

Neutral Density Filter (N/D)

Noise

NTSC

NVR (Network Video Recorder)

Ohms

Optical Filters

Oscilloscope

Outdoor Camera Housing

Outdoor Dome Housing

PAL (Phase Alternating Line)

Passive

PCMCIA Card

Peak to peak

Pelco-D

Photon

Pinhole Camera

Pixel (Picture Element)

Pixim Cameras

Power Over Ethernet (PoE)

Polarizer

Post-Record

Potentiometer

Power supply

PPP (Point-to-Point Protocol)

Pre-Record

Pressure mat

Progressive

Protocol

PTZ Camera

PTZ controller

QCIF see Resolution

Quad Splitter

Range finder

Raster

Real time video

Reed switch

Reflected Light

Regulated power supply

Remote monitoring

Resolution

RF (Radio Frequency)

RG-6/U

RG-11/U

RG-59/U

RGB (Red Green Blue)

Ripple factor

ROI (Region of Interest)

Router

RS232 (or RS-232)

RTP (Real-time Transport Protocol)

RTSP (Real Time Streaming Protocol)

SAD (Sum of Absolute Difference)

Scanning

Security Camera

Sensitivity of a surveillance camera

Sequential switcher

Shutter speed

Simplex

Signal to Noise Ratio (S/N)

SMS (Short Message Service)

SMTP (Simple Mail Transfer Protocol)

SNR Signal-to-Noise Ratio

Spot Cam

Static IP address

S-Video

Sync generator

Synchronization

TBC (Time Base Corrector)

TCP/IP (Transmission Control Protocol/Internet Protocol)

Telemetry

Telephoto lens

Test Pattern Generator

Time lapse VCR

.

Touch Screen

Tracking

UDP (User Datagram Protocol)

UPS (Uninterruptible Power Supply)

URL (Uniform Resource Locator)

UTP (Unshielded Twisted Pair)

Varifocal Lens

Vertical resolution

Vibration sensor

Video amplifier

Video Compression

Video distribution amplifier

Video intercom

Video server

Video Splitter

Video streaming

Video surveillance

WAN (Wide Area Network)

Wavelength

Wavelet

WDM (Wavelength Division Multiplexing)

WDR Wide Dynamic Range

Webcam

White balance

Wide angle lens

Wide Dynamic Range WDR

Wireless

Y/C

YIQ (Luminance In-Phase Quadrature)

YUV (Luminance Chrominance)

Zoom lens

Zoom ratio

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