Security-Kits :: CCTV Glossary of Terms

CCTV Glossary of Terms

Glossary of Common CCTV Terms

A

24 Hour Real Time VCR : A VCR that records video images at 2 to 4 times that normal rate of a time lapse recorder. These specialized tape recorders can record up to 20 images per second and record up to 24 hours on a standard T-160 video tape.

AC Power : Alternating Current - AC Power is commonly used to power security cameras. In alternating current circuits, energy storage elements such as inductance and capacitance may result in periodic reversals of the direction of energy flow. If a camera requires AC power then it cannot be used with a DC (Direct Current) power supply. Some security cameras can utilize either AC or DC (Direct Current) power.

Activity Detection : A feature of digital video that looks for changes in an image from frame to frame. By monitoring changes in the pixels, activity detection can cause a digital video recorder to begin recording, or tell an IP/Internet security camera to begin transmitting video.

AGC : Automatic Gain Control. This feature makes adjustment for lighting changes such as bright reflections from glass or headlights passing through the image to provide a more balanced lighting level. AGC reduces signal to noise ratio so that a higher quality recording can be achieved even in harsh lighting conditions.

Alarm Recording : To begin recording or increase a recording speed as a direct result of an external alarm trigger such as a panic button or advanced digital motion activity detection.

Alarm Search : A feature that allows recordings to be searched based on alarm events such as external alarm triggers or video motion detection.

ALC : Automatic Lens Control is an output on the camera that controls the auto iris lens adjustments for speed and sensitivity which makes a picture higher or lower contrast depending on lighting conditions.

Aliasing : Refers to an effect that causes digital cameras viewing different continuous signals to become indistinguishable from each other which causes distortion. For example, if your security camera is viewing a brick wall with a repeated pattern, it can become distorted by spatial aliasing and reproduce a distorted pattern. Aliasing is much more pronounced at lower resolutions than at higher resolutions.

Amp : Short for ampere which is a unit of electrical current that is a measurement of the amount of electrical charge per unit of time. In security electronics wiring terms, it is the measurement of the number of electrons passing through a given point in a one second interval. Security cameras and other electronic devices will only draw as many amps as they need to perform their intended function. A shortage of amperage due to demand or voltage drop due to insufficient wire size will cause electronic devices to operate incorrectly. Providing additional amperage will not cause any harm to an electronic device unlike voltage, which can destroy electronics.

Analog Video Signal : Electrical charges used to transmit a video signal from a security camera to a display or recording device. The signal contains the brightness and color of the image as a composite video signal. Modern security cameras create digital video images and then convert them to analog to transmit the signal over coaxial cable and to be recorded on VCR’s. Digital video recorders actually convert the analog video signal back into a digital format for recording to a hard drive.

Analog Camera : A closed circuit television camera which transmits an Analog Video Signal. Most modern closed circuit cameras create digital video images and then convert them to analog for transmission to a recording or viewing device with coaxial cable.

Analog Recorder : A video tape recorder or VCR which uses video tapes as opposed to digital storage devices.

Aperture : The lens opening that controls the amount of light reaching the imager. The Aperture size is represented as an ‘F-Stop’ number. Larger F-stop numbers (F/1.4, F/1.8, F/2.8, etc.) represent smaller openings, which allow less light in.

Aspect Ratio : Ratio of picture width to height. Closed circuit television equipment normally has a 4:3 aspect ratio which is 4 units high to 3 units wide while widescreen images are normally in 16:9 ratio.

Archive : In closed circuit television, archive typically refers to the long-term storage of video. Depending on the hard drive capacity, archived video can be kept within the recorder, on a RAID array (redundant array of independent disks) or stored on external hard drives.

Audio Recording : Most closed circuit television recorders have an audio input which allows them to record or listen to live audio. Due to privacy concerns, most security cameras do not have built-in microphones so in order to record audio; a separate microphone would be required. In many cases, audio recording is illegal if you are recording private conversations without consent or knowledge; therefore it is best to consult your local officials to determine legality before setting up an audio recording system.

Auto Focus : A feature of high end zoom lenses and cameras where the lens automatically keeps the correct focus throughout the zoom range.

Auto Flip : A feature of high end pan tilt zoom cameras that allow them to flip 180 degrees when a target passes directly underneath the camera.

Auto Iris : Refers to a feature of many cameras where the camera detects the amount of light entering and opens or closes the iris automatically to ensure that the image does not end up too bright or too dark.

Average Image Size : The average size of an image as recorded by a digital video recorder which is sometimes used to estimate the storage capacity of a DVR. The average image size can vary greatly depending on the compression format and the amount of motion or changes in the picture.

American Wire Gauge (AWG) :American Wire Gauge also know as the Brown & Sharpe wire gauge is a system used to determine the diameters of round, solid electrical conducting wire. Thicker wire has a lower gauge number; thinner wire is a higher gauge number.

B

Back Focus : A camera adjustment that allows the imager to move closer or further away from the lens to fine tune the focus. Back focus is commonly used to compensate for the different mounting styles of CCTV lenses, such as C and CS mount lenses.

Back Light : Strong lighting in the target area that makes the picture appear to be dark or as a shadow.

Back Light Compensation (BLC) : Refers to the electronic processing of video signals that can reduce the darkness and shadowing effects caused by strong lighting in the target area. Back light compensation can increase the brightness of objects in the picture that would normally appear dark as a result of strong lighting in the background.

Balun : A device used to convert a video signal so that it can be transmitted over a UTP (Universal Twisted Pair) cable. Many video baluns can increase the relative distance that a video signal can be transmitted to several thousand feet.

Bandwidth : In reference to the internet and digital video, bandwidth refers to the available speed for an internet connection, and may refer to the speed of transmitting data (Upstream Bandwidth), or downloading data (Downstream Bandwidth). The more Bandwidth available, the faster the transmissions will be. Higher bandwidth allows viewing of more cameras at higher frame rates.

Bandwidth Throttling : A feature in many digital video recorders that allows them to limit the amount of bandwidth they utilize to transmit files so they don’t disrupt other network traffic.

Blanking : A feature of some cameras and digital recorders that blocks parts or all of the image from being viewed by the system operator. Many high end pan tilt zoom cameras offer proportional blanking so that wide angle images are not obscured, but telephoto views of windows or other private areas can be blocked from view

Baud Rate : The rate at which data is transmitted between two devices. Also known as the symbol rate, which represents the total number of changes per second. For the devices to be able to communicate, they must both be operating on the same Baud Rate.

Binary : A binary file is a computer file which contains data encoded in a binary form. Binary numbering is a base 2 numbering system in which all digits are represented by a 0 or a 1. Pan tilt zoom cameras, keyboard controllers and other devices which require addressing to operate will typically use dip switches to create their binary addressing.

Bitmap (BMP) : A type of image file format used to store digital images. This is an uncompressed file format used by windows and other operating systems. Since bitmaps are not compressed and each pixel is represented individually, these files are usually very large.

Bloom : A reference to a streak or a smear in a video image that is normally caused by an area of extreme brightness.

Board Camera : A CCTV video camera mounted directly to a circuit board and normally delivered without a case or enclosure of any kind. Normally used as a spy or hidden camera

BNC : The standard RF signal connector for coaxial video cables used in security applications. BNC connectors use a bayonet type locking system with two protruding posts on the female end, while the male end has a rotating sleeve which slides over the posts then twists a quarter turn to lock tightly.

Braid : The woven metal mesh surrounding a center conductor to shield it from electromagnetic interference. The braid is grounded, while the center conductor carries the signal.

Brightness : A term used to describe the overall photometric luminance or reflection of light A video adjustment which controls how light or dark the image appears on a camera or video monitor.
Bullet Camera : Small cylindrical security camera. Normally tube shaped camera with or without infrared illuminators.

C

Category 3 Cable : Twisted pair cable that is capable of data speeds up to 16 megabits per second. Cat-3 Cable is typically used for telephone and video transmission/distribution systems.

Category 5 Cable : Twisted pair cable that is capable of data speeds up to 100 megabits per second. Cat-5 Cable is typically used for computer networking and video transmission/distribution systems.

CCD : Charge-coupled device is an electronic capacitor array or a photosensitive image device that captures the light that passes through a camera lens and transforms it into an electrical charge which captures a two dimensional image of the scene projected onto it. Light passes through the iris, is focused by the lens, and lands on the CCD where the image is generated.

CD : CD’s or Compact Disks are a common, inexpensive media for storing audio and video. CD’s can store up to 800Mb of data.

CCTV : Closed Circuit Television. This references a television/camera system which does not openly transmit or broadcast an image, but rather directly transmits the video signal to a specific place. The increasing use of CCTV has allowed people to purchase and install CCTV systems for personal, private or commercial use.

C-Mount : A closed circuit television lens mount that extends 17.5-mm into the camera. One of two styles of mount for a camera lens, this style was developed first and is present on older cameras. A C-Mount lens can be used with a CS-Mount camera with the aid of a special adapter.

CS-Mount : A closed circuit television lens mount that extends 12.5-mm into the camera. The newest of two styles of mounts for a camera lens. The CS-mount lens is prevalent on most newer cameras. The lenses are smaller, more compact, and less expensive. A CS-Mount lens cannot be used with a C-Mount camera.

Coaxial Cable : The most common type of cable used to transmit video signals; this cable has a single copper center conductor through which the signal is transmitted, surrounded by insulation and braided shielding. Because of its construction, an RG-6 coaxial cable allows video transmission at distances up to 1,000 feet.

Coaxitron : A technology developed by Pelco CCTV systems that allows the camera pan tilt zoom control signals to be transmitted up the shield of a coaxial cable. This technology saves money because you do not need to run a separate control wire for the RS-422 Data that controls the camera. Other manufactures use up the coax technology under different trade names, but they are all very similar.

Compact Flash : A removable storage media that can store images and video clips on a small electronic card that can be erased and re-formatted.

Covert Camera : A CCTV camera disguised as another device such as a clock radio, picture frame or a motion detector.

Codec : A Codec is a device or computer program capable of encoding and or decoding a digital data stream such as video from a security camera. Video images can generate very large file sizes so manufactures use Codecs to compress video files to make them smaller and easier to work with. The same video codec is then used to view the compressed video when you call up any recorded or archived footage.

Contrast : A measurement of the luminosity of an image and the differences between the dark areas and colors and the lighter areas and softer colors of the image.

CPU : Central Processing Unit or CPU typically refers to the main processor used in a computer system. The speed of the CPU directly affects how a computer handles multiple tasks, such as viewing a large amount of cameras or recording/playing back video. Faster processors can generally perform more tasks at the same time, and as such are vital for viewing and recording larger amounts of cameras.

Crosstalk : Cross channel interference can be defined as pieces of data or signal that leak from one connection to another. In video security systems, crosstalk can create ‘ghosting’, or overlapping of video images. Twisted pair cabling can often be used to reduce the effects of crosstalk.

CRT : Cathode Ray Tube; A CRT is a vacuum tube containing an electronic gun and a fluorescent screen. Older style televisions utilize CRT displays but in recent years, LCD and plasma display screens have largely replaced the older technology. CRT have a longer mean time between failure rate than LCD or Plasma displays and many people feel they provide superior picture quality.

Cruise : A pre-programmed pattern for Pan/Tilt/Zoom cameras. When a PTZ camera is placed into “cruise” mode, it will simply repeat the programmed pattern again and again. This can be very helpful when a PTZ camera needs to cover a large area of specific points such as a parking lot or a concert hall.

D

Decibel (dB) : Decibel; This is a measurement of signal strength relative to power. Higher dB represents a stronger signal. Decibels represent a convenient way to represent a logarithmic scale that roughly corresponds with human perception.

DC Power : Direct Current is the unidirectional flow of electrical charge. Most commonly found in low voltage systems such as security cameras, direct current flows in a constant direction which distinguishes it from AC or alternating current.

DC Auto Iris : Lens that is controlled by the camera. Sensitivity adjustments to the lens are made on the camera.

Depth of Field : Range of which all objects in a lens field of view are in focus. The depth of field can change when the light level changes.

DHCP : Dynamic host configuration protocol or DHCP is a type of firewall program that uses IP addresses which are assigned by the internet service provider to mask the IP address of a connected device

Digital Video Signal : In video security systems, a digital video signal represents a waveform that switches between two voltage levels that represent a 0 or a 1. It differs from an analog video signal because the video is transmitted as individual packets of data rather than a single electrical signal.

Digital Video Recorder (DVR) : A video recording device that records images to hard disk drives or other digital recording media such as a CD, DVD or Flash Memory card. Digital video recorders have quickly become the gold standard of the security industry.

Digital Signal Processing (DSP) : DSP is a type of electronic processing of video signals to clean up any noise and enhance the picture.

Digital Zoom : Digital zoom allows a security camera or a digital video recorder to zoom into a picture for closer inspection. Not to be confused with optical zoom, digital zoom is accomplished by cropping down an image and then interpolating the results back to the original image size, thereby decreasing the image resolution.

Distortion : Distortion is the alteration of the original shape, size or characteristics of a video image or file. In video systems, distortion is normally caused by close proximity to high voltage electrical sources or it is due to bad grounding.

Dongle : A dongle is in effect, a hardware key or token that plugs into a computer to unlock functionality within software programs or packages. Dongles are typically used on high end software applications, but there are potential weaknesses in the implementation of dongles as security devices or hardware keys. Manufacturers are combating this with copy protection, encryption and other fabrication techniques to thwart reverse engineering.

Dot Pitch : A specification for a computer display that describes the distance between pixels on a computer printer, monitor or scanner. A smaller dot pitch number means closer spacing which generally produces a sharper image.

Duplex : A communication system that can send and receive data in both directions simultaneously. In video surveillance systems, duplex sometimes refer to the ability of a video multiplexer to playback and record video at the same time.

E

Embedded DVR : An embedded digital video recorder is a special purpose computer that is designed for one special purpose, to record video. Another name for a stand-alone DVR, an embedded digital video recorder uses a real time operating system such as Linux to increase the reliability and performance of the recorder. An embedded DVR does not require a PC or other computer in order to operate.

Encryption : A method of securing data by transforming information using an algorithm to make it unreadable to anyone except those that posses the key. Encoding makes it unrecognizable until de-encoded/de-encrypted. This is used to prevent unauthorized viewing of secured data.

Ethernet : A complex networking technology that is the backbone of most local area networks. Ethernet computer work stations communicate by sending each other data blocks that are individually sent and delivered. Ethernet networks are often used to connect IP cameras, DVR’s, Printers, and other similar devices to be viewed from a central source.

Event : A special occurrence which triggers a response from the DVR; examples are when motion is seen by a camera, when a foreign object is placed within the camera field of view, when a camera loses video, etc. Different DVR’s can perform different functions for certain events, such as trigger recording or sound alarm, or even e-mail or phone notifications.

F

F-Connector : Screw on type connector for coaxial cable. F connectors are most common in television and satellite equipment and cabling.

F Number/F Stop : A relative measurement of a lenses ability to gather light. Each step up reduces available light by half while each step down doubles the available light.

FCC : Federal Communication Commission; a US government agency which regulates the use of the radio and television broadcasts as well as al interstate telecommunications.

Fiber Optics : An optical fiber made of glass or plastic that carries light along its length used for communication and data transmission. Fiber optic cables have much less loss than copper conductors and can therefore support data transmission over longer distances and at higher data rates.

Firewall : A software program or hardware device which protects a PC or a network by selectively blocking access from the outside. If a firewall is in use it must be properly configured before a camera system can be viewed remotely.

Fixed Lens : A lens which has a set focal length so it does not have the ability to zoom in or out.

Focal Length : The distance between the lens and the imaging chip of the CCD. The focal length affects the angle of view and viewing distance of the camera. A larger focal length has a narrower view, while a smaller focal length provides a wider angle view.

Foot-Candle (fc) : A measurement of light intensity. 1 foot candle (fc) is equal to 10 lux. 1 lux is equivalent to the light provided by a full moon at night.

Frame Rate : Frame rate refers to the speed at which still images or pictures are recorded in a 1-seond period. Real time video is considered to be approximately 30 images per second, but most surveillance system recorders reduce that rate to save disk space and processing power. The more frames that are recorded each second, the more smooth and fluid the playback.

G

Gain : Gain is a measure of the ability of a circuit to increase the power or amplitude of a signal. In security cameras, it references an increase in the signal and is measured in decibels (dB).

Gamma :A measurement of the brightness of the screen. Typically turning up the gamma will make the screen brighter which makes darker colors easier to tell apart. Excessive gamma can make the screen look washed-out or over bright.

Gigahertz (GHz) : The Hz symbol is a unit of measure for frequencies per unit of time, or the number of cycles per second. A gigahertz is equal to 10 to the 9th power. The term is most commonly used when referring to wireless transmissions.

Gigabyte (GB) : A measurement of data, 1 GB is equal to 1024 Megabytes (1,073,741,824 bytes). This term is frequently used to refer to the amount of storage present in a Digital recorder; the more GB available, the longer a DVR can record for.

Grayscale : A term used to reference black-and-white video, where colors are represented as varying shades of grey.

Ground Loop : Interference caused by current flow due to ground differences between devices. A ground loop usually causes interference to the video signal.

H

H.264 Compression : H.264 is a very high quality video codec. The H.264 codec provides superior video quality with much lower file sizes. Without compromising image quality, H.264 video compression can reduce the size of a digital video file by more than 80% compared with the Motion JPEG format and as much as 50% more than with the traditional MPEG-4 standard.

Hardwired Camera : A term used to reference cameras which must be physically connected to a wire to transmit video as opposed to a wireless camera. The term can be applied to traditional CCTV cameras which utilize coaxial cable or some other form of hardwired video transmission.

HDD : Hard Disk Drive. A physical storage device for Digital recording systems such as PC’s and standalone DVR units. Providing HDD units with more available space allows you to keep clips for longer amounts of times before they need to be erased to make room for new clips.

Hidden Camera : A hidden camera is placed inconspicuously so as not to be seen, either in a difficult-to-see location or when placed within another object such as a motion detector or a clock radio to disguise the camera. The term can also mean a camera which is not displayed on the camera monitor but still recorded, so that observers of the monitor do not know of the existence of that camera.

Housing : An enclosure used to contain and protect the camera from the environment, damage, tampering, or detection. Most camera housings are designed to protect the security camera from the moisture and temperature variance found in an outdoor environment.

Hub : A switching and control point for PC networks. A hardware device which provides network connection ports for multiple network devices such as computers, DVR’s or IP addressable security cameras.

Hue : Hue is used to describe and distinguish between similar colors with different lightness and color quality such as light blue, vivid blue, etc. Adjusting Hue on a security camera can vary the color rendering of objects that appear in the picture.

Hybrid DVR : The term hybrid DVR refers to a digital video recorder that has the ability to simultaneously record traditional CCTV cameras connected with coaxial cable as well as internet addressable security cameras connected through a network connection.

I

I/O Device : Input/Output device, refers to a device which receives and transmits data through the use of alarm inputs . This primarily refers to devices which act as relay input/outputs, and can either receive a signal from an external device or transmit a signal to an external device. Examples are triggering recording from an external (hardware) motion sensor, or turning a siren on or off.

Imager : An imager is a photosensitive charged-coupled device (CCD) that is used in digital cameras to capture the light from the lens and transform it into an electrical signal. An imager has a capacitor array, each of which accumulates an electrical charge proportional to the amount of light focused upon it.

Infrared Illuminator : A light or series of light emitting diodes that are used to allow security cameras to see in total darkness. Infrared light is used to augment the available ambient light and it is normally invisible to the human eye, but can be picked up by security cameras which makes it great for covert surveillance.

Interference : Undesired distortions of a signal caused when an outside force affects it. Strong power sources can modify or alter a video signal which causes the picture to become fuzzy, distorted or full of static.

Interlaced : A method of displaying an image onto a video monitor which involves displaying all of the odd numbered lines in an image and then displaying all of the even numbered lines in an image. Each set of lines is drawn 60 times every second, and since it requires both sets of lines to display an image this results in a display of 30 images per second.

Internet Service Provider (ISP) : A company that offers and provides a locally accessible connection to the internet. ISP’s may provide high speed internet connections, e-mail service, web site hosting and other services to its clients.

Internet Video Transmission : Transmitting video over the Internet that is viewable by other devices that are connected to the Internet. Digital video recorders can allow remote viewing software packages and IP addressable security cameras can also broadcast internet video transmission.

IP Address : An internet protocol (IP) address system used to identify a single device such as a computer, internet addressable camera or a printer on a network. Local area networks typically have private addresses assigned to each device, where a device connected directly to the internet will have a public address assigned to it.

Iris : The iris is a mechanical device used in CCTV cameras which mimics the function of the human eye to control the amount of light focused on the imager. The iris controls the Aperture; opening up and enlarging the aperture to allow more light in, or closing and shrinking the aperture to allow less light in.

J

JPEG : JPEG is a commonly used method of video compression for photographic and video images. JPEG allows the degree of compression to be adjusted to provide a balance between storage size and image quality. JPEG compression can achieve 10:1 compression with no perceptible loss in image quality. JPEG is an acronym for the committee that created the compression format, the Joint Photographic Experts Group (JPEG).

K

Kilobyte (KB) : A measurement of the size of digital data; a Kilobyte is 1000 bytes. It is normally used when measuring smaller amounts of data, such as the amount of data being transferred each second with high-speed internet, or the size of individual compressed image files. 1 thousand kilobytes produces one Megabyte, while 1 million kilobytes produces 1 Gigabyte.

L

LAN : Local Area Network, a network which provides a connection to multiple computers within a small area such as a home or an office.

LED : An LED (Light Emitting Diode) is a small electronic diode that emits light when an electrical charge is applied. LED’s are widely used as indicator lights on electronic devices and they are also used with to provide area lighting for infrared night-vision cameras.

LCD : A Liquid Crystal Display monitor. LCD monitors re thin flat panel monitors that have lower power requirements and are much thinner and lighter than CRT based monitors.

Level : Level is an adjustment on an auto iris lens which makes the picture brighter or darker.

Line Lock : The process of synchronizing security camera and video monitors with the AC power phasing to reduce picture roll. Used in large matrix switching systems to reduce the rolling of images when cameras that are powered from different AC sources are switched on monitors in a control center.

Lens : An optical device which gathers light and focuses it onto an imager. Lens focal length determines how narrow or wide the area of view is.

Looping : Looping refers to the ability for a closed circuit video signal to pass through an image management device such as a digital video recorder or a security monitor to another device. For example, video from a security camera can loop through a DVR and then be displayed on a video monitor.

Lux : Lux is a measurement of light intensity and it is often used to refer to the lighting level required for a security camera to provide usable images. Low-Light cameras can often see in lighting conditions ranging from .01 to .1 lux, while standard security cameras require 1 lux or more to operate. 1 lux is equivalent to the light provided by a full moon at night.

M

MHz : The Hz symbol is a unit of measure for frequencies per unit of time, or the number of cycles per second. A megahertz is equal to 10 to the 6th power. The term is most commonly used when referring to wireless transmissions and data transfer speeds.

Manual Iris : A CCTV lens that has an iris which is adjusted manually to widen/shrink the aperture to control the light levels.

Matrix Switch : A CCTV switcher that accepts and controls multiple camera inputs and multiple monitor outputs. A Matrix Switcher provides you with the ability to switch any camera to any monitor based on manual control through a keyboard or from any number of alarm or time based events.

Megabyte (MB) : A measurement of the size of computer storage. A megabyte is equal to 1,000,000 bytes or 1024 kilobytes and it is commonly referred to as MB.

Milliamp (Ma) : A measurement unit of electrical current equal to 1000th of an amp. In household terms it is the number of electrons passing through a given point in a 1-second interval.

Modem : A device that modulates an analog carrier signal to encode and decode digital information to produce signals that can be transmitted over phone lines or hardwired connections. A modem provides the ability for a PC to communicate over the internet, or electronic devices to communicate over long distances on a dedicated wire connection.

Monochrome : A term used to reference black-and-white video cameras or black and white CRT video monitors.

Motion Detection : Motion detection is a common trigger for cameras to begin or stop recording. Many modern digital video recorders support digital video motion detection where the video is analyzed for motion or changes in pixels. When enough of a change occurs, the system begins recording video to the hard drive. By recording video only when motion occurs a user can save hard drive space by not recording ‘empty’ times when nothing is happening. External motion detectors can also be used to trigger recording when they are tied into a DVR and programmed as an alarm input. This method is more reliable for high security applications because motion detectors are less susceptible to false alarms.

MPEG : MPEG is a commonly used method of video compression for video images. MPEG allows the degree of compression to be adjusted to provide a balance between storage size and image quality. MPEG compression consists of 4 different parts, MPEG-1, MPEG-2, MPEG-3 and MPEG-4. MPEG is an acronym for the committee that created the compression format, the Moving Picture Experts Group (MPEG).

Multiplexer : An image management device that allows full frame recording of multiple security cameras on a single video tape. The multiplexer records camera 1 on frame 1, camera 2 on frame 2, camera 3 on frame 3 and so on. A multiplexer can provide time-lapse recording without any loss in quality due to the screen being divided although it does slow down the toal number of images per second recording that is available.

N

National Electrical Code (NEC) : An installation standard for cabling , wire and electrical equipment.

Network Camera : A surveillance camera with a built in network transmitter that uses TCP/IP to stream video over a local area network or the internet. Also referred to as an internet camera, a system of network cameras can be deployed all over the world and viewed and recorded from a centralized network video recorder.

Network Video Recorder (NVR) : A digital video recorder designed to record surveillance camera video directly from a network connection. Also referred to as a network DVR, a NDVR can view and record multiple network security cameras deployed anywhere in the world.

Noise : In any electronic circuit, there exists random variations in current or voltage caused by random movements of the electrons. Noise can be introduced into the circuit by internal “thermal” noise, signal loss over distance, or from intrusion by an outside signal or power source. Noise is also present in video and images and is referred to as grain. I.e., the picture is grainy. Noise can never be eliminated entirely, but can be minimized to unnoticeable levels.

Non-interlaced : Another term for Progressive Scan, which is a method for displaying, storing or transmitting moving images in which all the frames for each image are drawn in sequence. Non-interlaced or progressive scan provides better pictures; smoother transition and less flickering, but requires more powerful hardware to keep up with the additional bandwidth requirements.

NTSC : The National Television System Committee or NTSC represents the analog television format as used in the United States, Canada, Japan, Mexico, South Korea and Taiwan. Other countries, including Europe, utilize the PAL (Phase Alternating Line) format which is not compatible with NTSC standards. In the security surveillance industry, many devices allow you to select either NTSC or PAL format with a slide switch.

O

Object Distance : A term used to describe the distance from the security camera to the target viewing area.

Octopus Cable : A term used to describe a multiple-camera connector commonly found on the back of DVR cards and PC-Based DVR units. With these connectors each camera plugs in individually but connects to the DVR at a single port. This term is often interchanged with ‘Pigtail’ and ‘Dongle’.

Ohm : A measurement of electrical impedance or resistance through a wire or circuit, shown as the symbol Ω.

P

PAL : PAL is an acronym for Phase Alternating Line which is considered to be the European video format, its counterpart is NTSC (National Television Committee) which represents the analog television format as used in the United States, Canada, Japan, Mexico, Taiwan and South Korea. . The two are not compatible and using the wrong video format can produce distorted images and video. PAL is used mainly in Europe, China, Malaysia, Australia, New Zealand, the Middle East and parts of Africa.

Pan, Tilt, Zoom (PTZ) : A reference to a feature of moveable security cameras wherein pan refers to the ability for horizontal movement, panning refers to vertical movement and zooming refers to the ability of the camera lens to vary its focal length. PTZ security cameras may be controlled with a matrix switcher, a multiplexer, a digital video recorder or with a joystick controller unit.

Partitioning : A feature of digital video recorders, multiplexers, internet cameras and matrix switchers that limits a users access to programming and features based on a security or password level.

Patch Panel : A patch panel refers to a termination and or a splice point for wiring and or fiber optic cable. Patch panel can refer to a centralized location where security, telephone, network or fiber optic cabling is “patched” together with jumpers for routing purposes.

PC Based DVR : A digital video recorder for surveillance cameras that uses video capture cards and software such as EZWatch-Pro to create a security camera recorder out of a normal desktop PC.

Phase Adjustment : A setting on video surveillance equipment that allows the cameras to be adjusted outside of the normal AC power phase to reduce rolling of images when switched between sources on a CCTV video monitor.

Pigtail : A length of wire which has one bare end and one end terminated in a connector. It can also refer to a connector on the back of a PC or DVR which has many individual camera connections but only plugs into a single port on the back of PC.

Pinhole Camera : A pinhole camera is normally a CCD board camera with a lens with a very small aperture or with an extremely small fixed focal length lens. Pinhole cameras are used for spying and are also popular with the scale model crowd. Pinhole style lenses can also be added to traditional box style security cameras and then hidden in walls or vents.< /p>
Plenum : A plenum is an environmental air space or an area above a ceiling which is used as a return or supply air shaft for heating, ventilation and air conditioning systems. Because plenum areas are used to provide airflow in HVAC systems, it may be required to use special “plenum rated cable” that does not release poisonous gases when exposed to flame or heat.

Polarized Antenna : A transducer designed to transmit or receive electromagnetic radio frequency(RF) waves. Polarization of an antenna is the orientation of the electric field of the radio wave with respect to the earth’s surface to reduce crosstalk.

Port : A numbered address in a router where requests are sent to and from, or an input on any CCTV surveillance equipment such as a multiplexer or a digital video recorder.

Port Forwarding : A method of forwarding information from one network port to another one located on a separate network. The technique can allow an external user to reach a port on a private IP address from an outside location. The ability to port forward is an essential tool to set up remote viewing of security cameras on a digital video recorder when the DVR is installed on a private network behind a router or a firewall.

Positioning Device : A device that allows a camera to be set to a specific scene or view by adjusting the horizontal, vertical and zoom positions.

Post Recording Search : A motion detection feature that allows a user to search for motion in a specific area of a live fixed camera image after that motion has occurred. A user can draw a box around an area of an image and then search for any motion based events that have occurred within the area.

Power Over Ethernet (POE) : A system for sending power over network cabling to internet addressable devices such as IP based security cameras or megapixel network cameras.

Pre-Alarm : Images stored in digital memory of events that occurred just before an alarm condition. Pre alarm images are used to show events leading up to an alarm. Modern security recorders store their video in random access memory (RAM), so if no alarm events occur, they simply throw the video away rather than fill up the hard drive. When an event is detected, the DVR will go back prior to the motion and begin recording so that nothing is missed leading up to the event.

Post-Alarm : Images stored in digital memory of events that occurred just after an alarm condition. Post alarm recordings are used to show events occurring just after an alarm. Post alarm recording is normally adjustable from 1 second to well over 60 seconds.

Preset Position : A preselected camera position and view for Pan/Tilt/Zoom cameras that is programmed into a unit with a keyboard or digital video recorder. Presets can be stored in a matrix switch or within the PTZ camera itself. Most modern PTZ cameras can store a large number of presets, and can be cycled through them one by one with a feature referred to as a preset pattern or cruise.

Private IP Address : An IP address assigned to a computer or an internet camera that is part of a private network. Typically these addresses can only be accessed from other computers on the same network. If a digital video recorder or an internet based security camera is on a private network this indicates that it is installed behind a router or a firewall and to access the cameras remotely the router will need to be configured for Port Forwarding.

Protocol : In security and telecommunications, a communication protocol is a set of standard rules for data representation intended to ensure reliability in data interchange over a communication channel. I.e. a protocol is used to communicate and configure Pan/Tilt/Zoom security cameras.

Protected Files : A feature of digital video recorders that allow certain selected images or video files to be protected so they are not overwritten by the first-in first-out (FIFO) features when the hard drive is full.

PSTN or POTS : These acronym are commonly used to refer to a public switched telephone network or plain old telephone system. A regular telephone line with dial tone.

Q

Quad : A device that allows four video surveillance cameras to be displayed and recorded simultaneously. A quad is normally used with a time lapse video recorder to allow multi-camera recording on a single video tape.

R

Radio Frequency (RF) : An alternating current electrical signal used to produce and create radio waves. An electrical current that is ionized to create a conductive path through the air used to send video and data signals.

RAID : Redundant array of independent disks feature multiple hard drives connected to a digital video recorder or other PC to provide extended storage or a redundant back-up.

Real Time : In video surveillance systems, real time is approximately 30 images per second.

Receiver-Driver : A digital device that receives control signals and converts them to relay or voltage outputs to control devices such as pan/tilt/zoom cameras.

Relay : An electrical switch which opens or closes to complete an electrical circuit. These are used to trigger functions within alarm or camera systems. Examples are motion detectors, which trigger when motion is seen and can signal the receiving unit to perform certain tasks – for a VCR/DVR unit, the relay can trigger recording, sirens, pan/tilt/zoom functions, etc. For alarm systems it typically triggers an alert which (if the alarm is active) will trip the alarm or cause a siren to wail.

Remote Live View : The ability to view a live image from a security camera system from a remote location using a dial-up or internet connection.

Remote Playback : The ability to view a previously recorded video clip from a remote location using a dial-up or internet connection.

Resolution : A measure of a security camera or a video monitors ability to reproduce detail which is equal to the total amount of lines that appears on the screen. Most computer screens are measured by both width and height (IE : 1024 lines wide, 768 lines tall) while most cameras are measured by TVL (Television Lines), or height alone.

RF Modulator : An RF modulator is a device that converts a composite video and audio signal into an RF signal that can be tuned by a television tuner. A device that provides the ability to display security camera video on a specific channel on your television set.

RJ45 : A jack and plug used for data transmission which is similar to an RJ11 telephone jack but has 8 pins or wires instead of 4.

RG-6-RG-59 : Types of coaxial cable frequently used in video installations. RG6 and RG59 are 75Ω (Ohm) coaxial cables. RG59 has a thinner center conductor than RG6 and for closed circuit television installations; it is recommended that the cabling have a 95% braided copper shielding.

Router : A device that acts as a bridge to handle different protocols and allow several devices to communicate and exchange information on a private network. Commonly used to split up an internet connection among multiple computers, a router can cause difficulties when viewing cameras remotely. To properly view cameras from a remote location through a router, port forwarding is needed to view the images.

RS232-RS485 : Recommend standard 232 is a communications protocol standard for serial binary data signals between DCE and DTE devices. RS485 provides for data transmission using differential signaling with non terminated lines in a point to point or a multi-drop configuration. The most common use of RS232 and RS485 communication in video surveillance systems are for communication to external devices such as a pan/tilt/zoom cameras or remote keyboard controllers. RS232 is an older standard which uses 3 wires to communicate and is limited to less than 50 feet, while RS485 only requires 2 wires and it operates at distances in excess of 2000 feet.

S

Saturation : The intensity of the colors in a video image. 100% saturated colors do not contain any white; adjusting the saturation adds white to an image which can improve brightness

Scan : A feature of Pan/Tilt/Zoom cameras where the camera rotates horizontally around. This is also frequently used to reference ‘Preset scanning’, also known as ‘Cruise’, where the camera moves from preset point to preset point.

Scanner : A device that allows horizontal movement of a camera. Scanners are typically used to pan back and forth to cover larger portions of a scene with a single video camera.

Signal to Noise Ratio (S/N) : Often abbreviated SNR or S/N the signal to noise ration is an electrical engineering measurement defined as the ration of a signals power to the noise corrupting the signal. Measured in decibels (dB), the higher the value, the stronger the signal is compared to the amount of noise.

Siamese Cable : A coaxial cable and a power cable combined into one overall jacketed cable which is normally used for video security cameras.

Simplex : In CCTV systems, the term simplex refers to the ability to perform one multiplexing function at a time, such as playback, recording, or remote viewing.

Single Mode : A fiber optic cable which only provides a single light path. Normally used for long distance fiber runs because it is more expensive, harder to work with and terminate but it works over much longer distances.

ST Connector : The most popular style of bayonet type fiber optic connectors for video surveillance applications.

Static IP Address : An IP address that remains the same each time your computer or a router connects to the internet. Especially useful for remote viewing applications because the IP address of the digital video recorder never changes so you can always connect.

Subnet Mask : A number which is used in conjunction with an IP address to subdivide the network into smaller identifiable areas.

Switch : A managed hub that routes files directly to their destination rather than broadcasting them over an entire network.

Switcher : A hardware device that allows cameras to be manually or automatically sequenced for display or recording purposes.

T

TCP/IP : Transfer Control Protocol / Internet Protocol is a protocol for transferring data between computers in a network or over the internet.

Telephoto : A lens that combines a series of lens elements to converge the light properties to make distant objects appear closer or magnified. A CCTV lens with the ability to zoom in on an object is considered to be a telephoto lens.

Terabyte (TB) : A measurement of digital storage which is equal to 1024 Gigabytes or 1048576 Megabytes.

Text Inserter : A device that overlays text from an electronic device onto the video from a security camera such as the overlaying the data output from a cash register.

Tilt : Refers to the vertical up and down motion of a pan tilt zoom security camera.

Time Lapse VCR : An analog video tape recorder which extends the recording time of a regular VHS tape from ~180 minutes up to 960 hours by taking still-frame images at regular intervals such as one image every 1, 5, 10, etc seconds. A time lapse recorder also superimposes a time and date stamp on each video frame for evidence.

Transformer : A device which steps down higher voltage into a lower voltage for use in security cameras and related equipment. A typical transformer will turn 120 Vac into 24 Vac.

Triplex : Refers to a device which can perform three functions simultaneously such as live viewing, recording and playback of video all at the same time.

Twisted Pair : A cable composed of two smaller cables twisted together. Twisted pair wire is often used for powering cameras or for data transmission. Common varieties of twisted pair cable include category 3 telephone cable and category 5 network and data cable. With the use of video baluns, twisted pair cable can be used to transmit security camera video, audio and data over relatively long distances.

U

UPS : Uninterruptible Power Supply. This refers to a battery backup device which provides power to electronic devices in the event of a power failure for a short period of time. The amount of power stored is measured in VA, or kVA and generally the higher the number the longer the battery can run when a device is draining power. A UPS can also protect expensive electronic equipment from damage caused by power bumps and brown outs.

USB Drive : A universal serial bus is a removable digital storage device that connects to a USB port of a computer or a DVR. A USB drive can be a fast efficient way to back-up and transfer digital video files from DVR to a computer.

V

Vandal Resistant Camera : A security camera housed in a heavy duty protective housing to help protect it from vandalism.

Variable Speed :A pan tilt zoom camera that can be moved slow or fast based on a proportional amount of movement from the joystick controller. Modern PTZ security cameras also control speed based on the amount or level of zoom. They slow down the movement of the camera proportionately based on the current zoom factor of the lens.

Varifocal Lens : A type of lens which can be manually adjusted to control the focal length to zoom in or out to achieve the desired filed of view.

Video Amplifier: A device that accepts input from a video camera and boosts the signal to a higher, more powerful level so that it can travel a longer distance. Video amplifiers can sometimes be used to clear up problems with video signals on wire runs that exceed the maximum allowable distance.

Video Auto Iris Lens : A video auto iris differs from a DC auto-iris in that the lens samples the video signal and adjusts the aperture accordingly to achieve the best picture. Adjustments to the iris are made on the lens as opposed to on the camera.

Video Graphics Array (VGA) : Video Graphics Array or VGA as it is more popularly referred, is a video signal used by computer systems and viewable on a majority of computer monitors. Computers and standalone DVR’s commonly have a VGA output where a standard computer monitor can be used to view the video.

Video Signal : A 1-Volt peak to peak streaming video signal being transmitted from the camera to a receiving device such as a DVR or a security monitor.

Video Motion Detection : A software feature that analyzes a video stream from a security camera for changes in pixels which represent motion. Many digital video recorders allow you to create several zones of detection as well as add masking in areas where you do not want to record motion, such as a busy street, or a tree moving in the breeze. Advanced analytics can even determine if an object is moving right or left, or is an object that is in the image suddenly moves or disappears.

Voltage : A measurement of the amount of force or energy in an electrical charge. Excess voltage can severely damage electronic equipment, while insufficient voltage can cause equipment to function incorrectly. Always ensure you are providing the correct voltage to your equipment to prevent failure.

Volt-Amp (VA) : A measurement of electrical power that is equal to the voltage times the amperage. This measurement is also referred to as wattage. All electronics devices will have a total wattage, or the peak amount of energy that it will draw from a power source.

W

Watermark : A security feature built into digital video recorders to insure that video images have not been tampered with. A digital watermark embeds an invisible code into an image or video stream that can be verified with special software provided in a remote viewing application.

Watt : A measurement of electrical power that is equal to the voltage times the amperage. This measurement is also referred to as volt-amps or VA. All electronics devices will have a total wattage, or the peak amount of energy that it will draw from a power source.

Wavelength Division Multiplexing (WDM) : WDM is a technology which uses the different wavelengths or colors of a laser light to carry different signals in a fiber optic cable. WDM allows huge increases in data capacity for fiber optic cables as well as allowing bidirectional communication over a single fiber.

Wide Area Network (WAN) : Wide Area Network is a term used to describe a network which spans large distances. Commonly used when connecting multiple buildings together between cities or even states. Any computer network that covers a broad area can be considered a Wan, including the internet.

Weatherproof/resistant : This term is used to describe a camera or housing designed to be placed in an outside environment where it may be subjected to rain, snow, wind, and other common outdoor conditions.

Waterproof : A camera designed to be submerged in water. Most weatherproof cameras are NOT waterproof and many waterproof cameras may not be recommended for use in certain outdoor situations such as extreme heat or cold.

White Balance : An adjustment of the intensities of specific neutral colors; especially white and gray to render colors other than the neutrals to display correctly and within established parameters.

Wide Dynamic Range : A feature of security video cameras that compensates for uneven lighting conditions by taking a high shutter speed image and a low shutter speed image and then combining them into a single image.

Widescreen : A type of display which uses an aspect ratio wider than 4:3. Most commonly refers to a 16:9 or 16:10 display ratio.

Wireless : A term used to describe the transmission of a video or data signal from point to point through the air.

Wireless Security Camera : A type of camera which incorporates a wireless transmitter built-in to it, designed to transmit either directly to a DVR or to a wireless receiver which connects to the DVR separately. There are wireless IP cameras that utilize an 802.11 wireless network and then there are the 5.8GHz wireless camera and receiver packages.

Z

Zero Light/Lux Camera : A security camera which can see in total darkness is referred to as needing zero light or zero Lux. The most cost effective way for a security camera to see in darkness is infrared illumination. Many camera provide their own IR illumination by utilizing light emitting diodes or LED’s as they are commonly referred to. Most infrared light is invisible to the human eye, but the illuminator or the LED’s can be spotted by their red glow. Some specialized high end security cameras can utilize night vision intensifiers that multiply the amount of existing light. These are sometimes referred to as star-light cameras.

Zoom Lens : A type of optical lens that can change its focal length and zoom in or out to bring a distant object into a closer view. Some security cameras offer both an electronic zoom and an auto-focus feature which automatically adjusts the focus based on objects in the frame. Most high end PTZ dome cameras offer zoom with auto-focus.

Zoom Ratio : A number used to describe how far a camera can zoom in on an object. Based on its widest angle, such as 5-mm, an 18x lens can zoom out to 90-mm. In simpler terms, an 18x zoom lens can magnify an object in the distance eighteen times. Many high end cameras have an optical zoom and a digital zoom for even further viewing.