Video Surveillance Glossary

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A

A.L.C. (Automatic Level Control) (Back to Top)

On AI lenses, also known as the peak/average control. Adjusting this control allows the auto iris circuitry to either take bright spots more into consideration (peak), bringing out detail in bright areas, or less into consideration (average) bringing out

Access Card (Back to Top)

Approximately the size of a credit card, these are specially coded cards given to employees and allow them access to secure locations or devices at work. Access cards utilize several technologies such as magnetic strips, Barium Ferrite, proximity (active or passive), and other methods. They are often ‘swiped’ and read by a device that allows the user or employee access.

Access Code (Back to Top)

Similar to a password, this series of numbers or letters enables a user to access a system or computer. At job sites an access code can be the system or process that oversees employees or cars both in and out of certain areas.

Access Point (Back to Top)

These are specific entry points in certain secures areas. A card reader and monitor switches allow authorized entry by individuals with access cards

Activity Detection Back to Top)

A feature of the Generation 3 video multiplexer range that uses video motion detection techniques to improve the camera update times. It also gives a relay closure.

Alarming (Back to Top)

The ability of CCTV equipment to respond to an input signal, normally a simple switch closure. The response varies depending on equipment type, most common is for switcher to ‘hold’ on the camera corresponding to the alarm input.

Alarm Input (Back to Top)

When attached to a security camera, an alarm input provides enhanced security in the form of a sensor device, often a door contact or a Passive Infra-red detector for motion detection. Alarm inputs can be self powered or can require external power (usually 12V).

Algorithms (Back to Top)

Its general definition means a set of mathematical instructions to solve a task. In the field of video technology, they enable digital compression of the video picture.

Ambien Light Level (Back to Top)

This is the amount of background light present at any specific time.

Analog (Back to Top)

A signal in which any level is represented by a directly proportional voltage; not digital.

Angle Of View (Back to Top)

The maximum scene angle that can be seen through a lens.

Anti-Passback (Back to Top)

A feature that will not allow any card to re-enter unless it has been used to exit. This requires that readers be used for both entry and exit.

Aperture (Back to Top)

The lens opening that controls the amount of light reaching the pickup device (imager).

ARP (Address Resolution Protocol) (Back to Top)

ARP is a method determining a host’s Ethernet address from its Internet address. The network receives the ARP request, and then names the IP address. Next, the machine at this address returns its physical address so the information can be sent to it. If supported by all hosts, Internet addresses can be independent of Ethernet addresses.

Aspect Ratio (Back to Top)

The ratio of the picture frame width to the picture frame height in standard TV systems. It is 4 units horizontal over 3 units vertical.

Aspherical Lens (Back to Top)

A lens designed with a non spherical shape so that it refracts the light passing through it to either lower the lens aperture so that it passes more light or decreases barrel distortion on wide angle lenses.

Attenuation (Back to Top)

A decrease or loss in a signal. Reduction of signal magnitude (loss) normally measured in decibels.

Auto White Balance (Back to Top)

Feature on color cameras whereby the camera constantly monitors the light and adjusts its color to maintain white areas.

Automatic Frequency Control (AFC) (Back to Top)

An electronic circuit used whereby the frequency of an oscillator is automatically maintained within specified limits.

Automatic Gain Control (AGC) (Back to Top)

Using a circuit built into the camera, gain control makes it possible to automatically maintain a constant output signal level even if there are changes in brightness. This makes it possible to obtain a picture with the same level of brightness regardless of whether it is taken in a dark or bright place. (Noise may slightly stand out) When a strong signal exceeding the set level is input, signal saturation is prevented by controlling gain. In the event that a weak signal is input, the signal is raised to correspond with the set level and this fixed level Is maintained .

Application Program Interface (API) (Back to Top)

This refers to the instruction and function sets that can be utilized when developing software as well as the established rule set for the program procedures that are necessary for employing these instruction and function sets.

Automatic Iris Lens (Back to Top)

A lens in which the aperture automatically opens or closes to maintain proper light levels on the cameras pickup device.

Automatic Electronic Shutter (AES) (Back to Top)

This is a function that automatically controls the device output level according to the incident light amount by utilizing the electronic shutter function of a solid-state image device.

Auto Negotiation(Back to Top)

Auto negotiation is regulated by IEEE802.3u. This function can be used to determine the appropriate transmission system for the corresponding device (HUB etc.) as well as select the optimum (highest possible speed) transmission method prior to transmission. When the corresponding device supports two or more of the transmission systems as well as the Auto Negotiation function, the high-priority items (fast transmission speed etc.) are given precedence. In the event that the corresponding device does not support the Auto Negotiation function, the transmission speed is automatically selected, but the automatic selection of full-duplex 1 half-duplex is not performed and half-duplex is always chosen.

Auto White Balance (AWB) (Back to Top)

When using CCD or film, pictures often come out reddish or greenish (orangish or bluish) in color when taken under incandescent or fluorescent light. AWB makes it possible to adjust white color balance under a wide variety of light sources. Automatic Tracking (Tracing) White Balance (ATW), Automatic White Balance (AWB), Automatic White Balance Control (AWC), Manual Mode and other features are available.

Auto-Terminating (Back to Top)

Feature whereby the equipment automatically selects the correct termination depending on whether the video output BNC is connected. AVC (Advanced Video Coding) (See H.264) Both the ITU and MPEG groups have agreed upon AVC as the current video compression standard. ITU calls it H.264, the MPEG group refers to it as MPEG-4.

B

Backlight Compensation (BLC) (Back to Top)

With backlight scene, the auto iris function responds to the bright portion of the screen, thus causing the iris to narrow and resulting in the "darkening of the subject" phenomenon. Backlight compensation is a function that can be utilized to correct this phenomenon.

Back Focus (Back to Top)

The mechanical aligning of the imaging device with the focal point of the lens. Most important on zoom lenses to ensure the image stays in focus throughout the zoom range.

Balanced Signal (Back to Top)

Method of transmitting video, usually over twisted pair cable, that consists of two equal but opposite signals being sent down two conductors.

Band Width (Back to Top)

The frequency range of a signal. The span that the information-bearing signal occupies or requires or the difference between the lowest and highest frequency of a band.

Base-Band Video (Back to Top)

Unmodulated video signal suitable for display on a monitor but not a domestic TV.

Black Level (Back to Top)

The level of the video signal that corresponds to the maximum limits of the black areas of the picture.

Blanking (Field And Line Flyback Blanking)

The operation of turning off the monitor display, or pick-up device, during sync pulses to avoid thin white lines appearing on the picture.

Blooming (Back to Top)

The halation and defocusing effect that occurs around the bright areas of the picture (highlight) whenever there is an increase in the brightness intensity.

BNC (Back to Top)

Video connector, the most commonly used in CCTV.

Bridging (Back to Top)

A term indicating that a high impedance video line is paralleled, usually through a switch, to a source of video. A separate overall video output.

C

C Mount / CS Mount (Back to Top)

The two industry standards for mounting a lens on a camera. The C-Mount lens has a 17.5mm flange back distance. The CS-Mount lens has a 12.5mm flange back distance.

C.C.I.R. (Back to Top)

The European TV standard 625 lines 50 fields.

Camera (Back to Top)

A device that translates light into a video image and transmits that image to a monitor for viewing. It contains the image sensor and other electronic circuitry to create a video signal.

Category 5 (Back to Top)

This refers to the quality assurance of connection parts such as unshielded twisted pair (UTP) cables and connectors. With LAN, category 3 is primarily utilized. For 100 BASE-TX, category 5 and above are used, and category 5e and above are required for 1,000 BASE-T.

Cathode Ray Tube (CRT) (Back to Top)

The picture tube in a video monitor that can reproduce the picture image seen by the camera.

CATV (Back to Top)

Short for Cable Access Television. The method for distributing RF signals via coaxial cable rather than radiated through the air.

CCD (Back to Top)

Charged Coupled Device. This is a solid state semiconductor imaging device often referred to as an integrated circuit, chip or "imager." Solid state cameras are sometimes referred to as CCD cameras.

CD-RW (Back to Top)

A CD-ROM that can be written, erased, and rewritten by a CD-RW drive.

Central Processing (On-line processing) (Back to Top)

A system where all systems information is stored in a central location and all go or no-go decisions are made by this unit.

Charge Coupled Device (CCD) (Back to Top)

A Charge Coupled Device is a semiconductor device that converts images to electrical signals.

Chrominance (C) (Back to Top)

The part of the video signal corresponding to the color information.

Closed Circuit Television (CCTV) (Back to Top)

Refers to a system of cameras and video accessory devices over an internal cabling path. Differs from broadcast video.

Compact Flash (CF) (Back to Top)

This is the standard for memory cards advocated by San Disk Corporation, and is utilized as a storage device for digital cameras etc. Compact Flash combines flash memory that does not go off even when the power is turned off and an I/0 controller circuit on just one card.

Common Intermediate Format (CIF)

This is the universal video signal format regulated by ITU-T H.261. CIF supports moving Images with a data rate of up to 30 frames per second and a resolution of 352 x 288 pixels.

Coaxial Cable (Back to Top)

A type of shielded cable capable of carrying a wide range of frequencies with very low signal loss.

Composite Video (Back to Top)

The complete video signal consisting of the video information, the sync pulse and threshold reference signal.

Contrast (Back to Top)

The range of light and dark values in a picture or the ratio between the maximum and the minimum brightness values.

Crosstalk (Back to Top)

An undesired signal that interferes with the desired signal.

CSMA/CD (Back to Top)

This is an access control method utilized for Ethernet transmissions. When collisions occur due to multiple terminals attempting to simultaneously make transmissions, the transmissions are stopped and then resumed after an appropriate amount of time has passed.

D

Db (Decibel) (Back to Top)

A measure of the power ratio of two signals. It is equal to ten times the logarithm of the ratio of the two the iris.

DC Type Lens (Back to Top)

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

Depth Of Field (Back to Top)

The area in focus in front of and behind the subject.

Digital (Back to Top)

A signal that levels are represented by binary numbers. These can be kept in a storage system.

Distribution Amplifier (Back to Top)

A device that accepts a video signal and sends it out over a number of independent outputs.

Distributed Processing (Back to Top)

An access control system where some of the system information is stored at the individual readers or controllers. This allows the system to operate when the host is down or not communicating.

Domain Name System (DNS) (Back to Top)

This system is used to replace IP addresses, which are expressed on the internet with numerals (e.g. 255.254.253.0), with domain names that are easy to remember. On the internet there are servers referred to as DNS servers that have IP address and domain name tables. By connecting to DNS servers, users can access the server that possesses the IP address via the domain name.

Door forced open (Back to Top)

A signal indicating that the door was opened without a valid card or request to exit device. This requires a status switch and some type of rex device.

Door held open (Back to Top)

A signal that indicates that the door was held open longer than it should have been. This is used to prevent someone from using a card to enter and then leave the door open for others. This requires a status switch on the door.

Dynamic Host Configuration Protocol (DHCP) (Back to Top)

This protocol is employed to automatically allocate IP addresses to clients when they turn on their PCs and then retrieve these addresses from them when they switch off their computers. On the server side, it is only necessary to collectively prepare several DHCP-client-use IP addresses. It is also possible to simultaneously provide clients with information such as gateway addresses, domain names and subnet masks.

Digital Signal Processor (DSP) (Back to Top)

This processor converts the input analog signal to a digital signal and then performs a variety of signal processing tasks. Thus, unlike analog processing, it is possible to produce stable and clear images without signal degradation within the circuit.

Dynamic IP Address (Back to Top)

A Dynamic IP address is a type of account from an ISP (internet service provider) where your computer or network is assigned an IP address that constantly changing and never remains the same. Also see IP Address and Static IP.

Dynamic Range (Back to Top)

This refers to the range within which the reproduction of images can be performed without adversely affecting gradation. The amount of light necessary for the luminance signal to reach the white peak at 100lRE (of the amount of light with which it is possible to perform the reproduction of images without clipping even when more light comes in than the amount stated above. In general, this is expressed in dB, % and times. Electronic Sensitivity Up is a function used to increase sensitivity by lengthening image device storage time beyond the norm or adding image signals to image memory via frames or field units.

E

Easy egress (Back to Top)

A means of exiting where the person wishing to leave simply turns the doorknob to exit.

E.I. (Electronic Iris) Shutter (Back to Top)

Electronic Iris shuttering is the ability of the camera to compensate for moderate light changes in indoor applications without the use of auto iris lenses.

E.I.A. (Electronic Industry Association) (Back to Top)

US TV standard 525 lines 60 fields.

Electronic Zoom (Back to Top)

This is a function that employs the scanning variable of an image device or image memory rather than an optic lens to electronically enlarge or shrink the Image on the screen.

Ethernet (Back to Top)

This is the LAN standard devised by Xerox Corporation, DEC Corporation and Intel Corporation, and has been standardized by the IEEES02.3. CSMA / CD has been adopted for data transmission over networks.

Equalization (Back to Top)

The process of correcting losses of certain components in a signal.

Ext. Sync (External Sync) (Back to Top)

The ability of CCTV equipment, normally cameras, to accept one or more of the standard sync formats so as to align itself to the rest of the system.

F

Fail safe (Back to Top)

Is a locking device that is unlocked when no power is applied.

Fail Secure (Back to Top)

Is a locking device that is locked when no power is applied. These are not normally used for exit doors since they cannot be unlocked during a power outage.

Fiber Optic (Back to Top)

The process of transmitting light through a long, flexible fiber such as glass or plastic, for the purpose of transmitting video, audio, or data over long distances.

Field (Back to Top)

One half of a frame of video (262.5 scan lines).

Field Of View (Back to Top)

The maximum viewed image (area covered) a lens "sees." The horizontal or vertical scene size at a given distance from the camera.

Flange Back (Back to Top)

The distance from the flange of the lens (beginning of the lens mount) to the focal plane. C-mount lenses have a flange back distance of 17.526mm vs. 12.5mm for CS-mount.

Firewall (Back to Top)

This is a software system that is used to prevent unauthorized entry into an organization's computer network from the outside. It also refers to computers with built-in firewall systems.

Focal Length (Back to Top)

The distance (in millimeters) from the lens to the surface of the image sensor. The shorter the distance, the wider the view; the longer the distance, the narrower (telephoto) the view.

Frame Rate (Back to Top)

This rate is established by V.Networks and refers to the number of frames transmitted per second for JPEG and MPEG 4 Images. The maximum frame rate is fixed for each image size depending on the specifications of the respective V.Networks models.

File Transfer Protocol (FTP) (Back to Top)

This is one of the communications protocols used when exchanging files over the internet. FTP is employed as the standard internet fiIe transfer method. Selecting FTP can often save time when downloading.

Focal Length (Back to Top)

The distance (in millimeters) from the lens to the surface of the image sensor. The shorter the distance, the wider the view; the longer the distance, the narrower (telephoto) the view.

Focus (Back to Top)

The focal point. An adjustment to the lens optics to improve the clarity of the picture.

Foot Candle (FC) (Back to Top)

A measurement of light. 1 lumen per square foot.

Format (Back to Top)

The size of the cameras pickup device (imager). Current standard formats are 1/4", 1/3" and 1/2".

Frame (Back to Top)

A complete picture (525 scan lines). The frame consists of two fields of video information.

FTP Client Function (Back to Top)

This is a V.Networks (VN-C30U / A1U / C11U) function that makes it possible to periodically (range of values: 0 to 86,400 seconds) upload images (JPEG still images only) to any FTP server. It is necessary to equip VN-A1U with a Compact Flash card.

FTP Server Function (Back to Top)

This refers to the V.Networks (VN-C30U / A1U / C11U) user page storage function. By utilizing any FTP client software program, HTML or JPEG image signals independently created by the user can be uploaded to VN-C30U / A1U / C11U. It is necessary to equip VN-A1U with a Compact Flash card (sold separately).

Full Duplex (Back to Top)

This is a transmission method by which it is possible to send and receive data simultaneously.

F Number (Back to Top)

This is a number that represents lens brightness; the smaller the number, the brighter the lens. The relationship between brightness IF Number), focal length (fI) and effective diameter (D) is described by the following equation: F = fl/D.

G

Genlock (Back to Top)

This is a type of external sync system with a function that synchronizes external sync signals with frequency and phase. There are three types of genlock input signals: composite sync signals (composite SYNC), composite video signals (VBS or VS) and Black Burst Signals (BBS).

Ghost (Back to Top)

A shadowy or weak image in the received picture, offset to either the right or to the left of the primary image.

Gigabyte (GB) (Back to Top)

1,024 megabytes or 1 billion characters of information. Also see Megabyte.

Gray Scale (Back to Top)

The number of variations from white to gray to black.

Ground (Back to Top)

An electrical connection point that is common to either a metal chassis, a terminal, or a ground bus.

Ground Loop (Back to Top)

Effects video pictures in the form of a black shadow bar across the screen or as tearing in the top corner of a picture. Caused by different earth potentials in a system.

GUI (Graphical User Interface) (Back to Top)

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

H.264 (also known as AVC [Advanced Video Coding] and MPEG-4) (Back to Top)

This is a standard for video compression. H.264 is a block-oriented motion-compensation-based codec standard. The H.264 standard and the MPEG-4 AVC standard are jointly maintained so that they have identical technical content.

Half Duplex (Back to Top)

This is a transmission method by which data cannot be sent and received simultaneously, but rather can only be transmitted in one direction at a time.

Hardwired (Back to Top)

Method of controlling camera points using multi-core cable.

Hub (Back to Top)

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).

Horizontal Resolution (Back to Top)

The maximum number of individual picture elements that can be distinguished in a single scanning line.

Hyper Text Transfer Protocol (HTTP) (Back to Top)

This is a protocol used by World Wide Web (WWW) servers and Web browsers for sending and receiving information such as files.

Hz (Hertz) (Back to Top)

Cycles per second.

I

IEEE1394 (Institute of Electrical and Electronics Engineers 1394) (Back to Top)

This is a next-generation, high-speed SCSI standard used to connect computers with peripherals and other devices. Both daisy-chain connections of up to 63 devices and tree connections are made possible by this protocol. The transfer speeds of 100Mbps, 200Mbps and 400Mbps have been standardized.

I.R. (Infra Red) (Back to Top)

A range of frequencies lower than visible red light used for covert surveillance or as a low cost wireless video link.

Iris (Back to Top)

The iris controls the amount of light taken in by the lens when changes in illumination occur. A manual iris lens is used when luminance is fixed, and an auto Iris lens is used in cases when luminance changes according to the time of day.

I.S.D.N. (Integrated Services Digital Network) (Back to Top)

Digital phone lines from which allow transmission of video signals via fastscan at speeds of 128Kb/second; used with terminal adapters.

Image Burn (Retained Image) (Back to Top)

A change produced in or on the target of the pickup device which remains after the removal of a previously stationary light image.

Image Device (Imager) (Back to Top)

The detector in the camera, either a tube or a CCD solid state device.

Image intensifier (Back to Top)

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.

Impedance (Back to Top)

The effective resistance of an electronic circuit to an A.C. signal.

Index of refraction (Back to Top)

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 (Back to Top)

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 detector (Back to Top)

This is an alarm that uses infrared light to detect nearby movement.

Infrared Illumination (Back to Top)

When a “low-light” is subject to dark conditions, active infrared illumination must be applied for best results. Active infrared illumination is a new surveillance technology that is so effective that the images produced are often mistaken for regular daytime monochrome images. Active infrared illumination is a cost-effective technology for enabling truly effective 24/7 surveillance in any lighting conditions including total darkness.

Infrared radiation (Back to Top)

Invisible to the human eye, this electromagnetic radiation has a wavelength of greater than 750 manometers.

Insertion Loss (Back to Top)

The signal strength loss that occurs when a piece of equipment is inserted into a line.

Intensifier (Back to Top)

An electronic device that creates an output image brighter than the input (original) image. Optical amplifier.

Interlace (Back to Top)

A scanning process where every other horizontal line is scanned in one field while the alternate lines are scanned in the next field to produce a complete picture frame.

Internal Sync (Crystal Controlled) (Back to Top)

A camera that generates its sync pulses without reference to any other source. Normally using a crystal controlled oscillator.

IP (Internet Protocol) (Back to Top)

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 (Back to Top)

The Internet Protocol address; a unique numeric address such as 123.231.32.2 Also see Static IP and Dynamic IP.

IP address (Back to Top)

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) (Back to Top)

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.

Iris (Back to Top)

The adjustable opening (mechanical diaphragm) through which light can pass and be regulated.

ISDN (Integrated Services Digital Network) (Back to Top)

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.

J

Java Applet (Back to Top)

This is a small program that is distributed from a WWW server to a Web browser (client) and then executed by the Web browser. It is used for the purpose of adding movement to the screen. When viewing the image of VN-C30U / C11U / A1U on Internet Explorer or Netscape, this program is utilized to display moving images.

Joint Photographic Coding Experts Group (JPEG) (Back to Top)

This is a standard established by ITU-TS (International Telecommunication Union: formerly known as CCITT) and ISO (International Organization for Standardization) that decides the compression and expansion of color still images. This technology makes it possible to compress still images from a scale of 1/10 to 1/100.

K

L

LAN (Local Area Network) (Back to Top)

A LAN is a high-speed network connecting computers that are nearby (probably in the same building), and offers differing connection protocol options.

Latency (Back to Top)

The speed of a network is dependent on both latency and bandwidth, with latency referring to the time needed for an IP packet to travel from source to destination. Wide bandwidth and low latency are preferable.

LED (Light Emitting Device) (Back to Top)

Monochrome surveillance cameras use LEDs to provide infrared light. An LED creates an infrared light frequency when stimulated by an electric charge.

Lens (Back to Top)

A transparent optical component that converges light rays to form a two dimensional image of that object.

Lens Mount (Back to Top)

Cameras have different types of lens sockets including C mount, CS mount and bayonet mount. C and CS mounts are screw-type mounts; C mounts have a flange focal length of 17.526mm and CS mounts have a flange focal length of 12.5mm. Bayonet mounts are often employed in three-chip cameras and this type of mount conforms to the standard for studio use cameras.

Level Control (Back to Top)

Main iris control. Used to set the auto-iris circuit to a video level desired by the user. After set-up, the circuit will adjust the iris to maintain this video level in changing lighting conditions. Turning the control towards High will open the iris, to

Light sensor (Back to Top)

Often used to turn infrared illuminators on or off, this device is triggered when it detects a pre-set amount of light, and helps cope with low (or no) level light conditions.

License Plate Reading (Back to Top)

License plate reading requires specialized equipment in order to successfully overcome the challenges related to speed, lighting, reflectivity and headlight glare. Cameras chosen should be designed specifically for license plate reading as most conventional cameras will not work on a consistent basis. Infrared lighting is typically required for performance during both day and night.

Line Amplifier (Video Line Corrector) (Back to Top)

A device to make good the loss of signal strength and quality due to long cable runs.

Line Lock (Back to Top)

This is a function that synchronizes the camera's vertical synchronizing signal with the frequency of the commercial power supply. The function can be used to reduce hum noise induction to the video signal and illumination flicker. If the image output of several cameras is switched, vertical synchronization disturbance, which occurs on the screen, can be prevented.

Limit switch (Back to Top)

A security camera’s pan and tilt head with one of these devices installed (either inside or outside it) is limited in the angles it can move.

Local Area Network (LAN) (Back to Top)

This refers to the connection of multiple computers or peripherals over a network within a confined area such as the same building, site or organization. Correspondingly, a computer network that goes beyond buildings or sites to connect LAN between remote locations is referred to as a Wide Area Network (WAN).

Looping (Back to Top)

A term indicating that a high impedance device has been permanently connected in a parallel to a video source. Individual balanced video outputs for each video input.

Lumen (Back to Top)

A lumen (abbreviated as lm) is a unit that measures the visible power output of a light. While watts measure the power the bulb needs, lumens measure the visible light that the bulb generates.

Luminance (Y) (Back to Top)

The part of a video signal that consists of the monochrome data.

Lux (Back to Top)

A unit measuring the intensity of light. One foot-candle = 10 lux.

M

Manual Iris Lens (Back to Top)

A lens with a manual adjustment to set the iris opening (F stop) in a fixed position. Generally used for fixed lighting applications.

Matrix Switcher (Back to Top)

A switcher able to route any of its camera inputs to any of its monitor outputs; a name usually reserved for large systems, that often includes telemetry control.

MATV (Back to Top)

Short for Multiple Access Television. The method for distributing RF TV signals by broadcasting them through the air.

MJPEG (Motion JPEG) (Back to Top)

Even though it’s not as efficient as MPEG-4, the MJPEG is still an effective way of creating video from the sequencing of JPEG images. The video from store security cameras often uses this method when being formatted.

MMS (Microsoft Media Services) (Back to Top)

MMS is the first streaming protocol created for the Microsoft Windows Media Player.

MOV (Back to Top)

Metal oxide varistor, a device used to prevent the emf generated by the locks from damaging the control.

MOD (Minimum Object Distance) (Back to Top)

This refers to the closest an object can be to the vertex of the lens and still be in focus. The wider the lens angle, the smaller the MOD.

Mimic panel (Back to Top)

This panel displays a site’s layout, including the location of surveillance cameras. When the panel is interfaced with a switcher, it can be used to switch any specific camera to the monitors.

Mechanical Focus (Back-Focus, Racking) (Back to Top)

The mechanical aligning of the imaging device with the focal point of the lens; most important on zoom lenses to ensure the image stays in focus throughout the zoom range.

Media Access Control (MAC) Address (Back to Top)

This refers to the unique address allotted to all devices connected 10 LAN, and is represented as a 16base, 12digit, 48bit (6 byte) address. The high 3bytes are assigned by the device's vendor 10 and the low 3bytes are assigned by a unique number from the vendor.

Megabyte (MB) (Back to Top)

1,048,576 bytes or 1,024 kilobytes. Used to measure computer memory. Sometimes used to mean 1 million bytes or 1,024,000 bytes (1,000 kilobytes). Also see Gigabyte.

Microwave (Back to Top)

Radio frequencies between 1 - 30 GHz used for video transmission over medium/long distance.

Minimum Object Distance (M.O.D.) (Back to Top)

The closest distance a given lens will be able to focus upon an object. This is measured from the vertex (front) of the lens to the object. Wide angle lenses generally have a smaller M.O.D. than large focal length lenses.

Minimum Illumination (Back to Top)

The minimum level of object illumination required for security cameras is referred to as "Minimum Illumination". The lower this value is, the higher the sensitivity of the camera. This value also serves as an indication of how dark of a place shooting can be carried out in. It should be duly noted that minimum illumination changes depending on both the F number of the lens being used and the reflectance of the object. If a security camera is used at a level close to the minimum illumination, the image may become blurred. Since this is undesirable, we recommend that sufficient illumination be used.

Modulate (Back to Top)

To change or vary some parameter such as varying the amplitude of a signal for amplitude modulation or the frequency of a signal for frequency modulation. A modulator is the circuit that modulates the signal.

Monitor (Back to Top)

A device that converts electronic signals into the video image that was generated by the camera and lens. The picture end of a CCTV system.

Monochrome (Back to Top)

Having only one color. In television it is black and white.

Motion Detection (Back to Top)

This is a function that alerts you with an alarm when there is motion in the image.

Motion-JPEG (Back to Top)

This is a technology that makes it possible to decompress still JPEG images at a high speed as well as make them appear as if they are moving by showing them in succession. This can also refer to the moving image data or the code that performs compression / decompression. Unlike MPEG data, which only records differential information between the frames of a moving image, motion JPEG makes it possible to edit any portion of a moving image because each frame is saved as a still image.

Moving Picture Coding Experts Group / Moving Picture Experts Group (MPEG) (Back to Top)

There are numerous standards such as MPEG 1. MPEG 2 and MPEG 4 for technologies utilized to compress digital moving Images. MPEG 1 takes into account storage / playback on storage media such as CD-ROM and has playback quality equivalent to that of VTR. MPEG 2 takes into consideration usage with broadcast media and has playback quality equivalent to that of HDTV. MPEG 4 is aimed at the distribution of low quality images at a high compression rate through the use of a slow-speed network.

Multicast (Back to Top)

This is a method that makes it possible to simultaneously transmit the same data to several specified computers.

Multiplexer (Back to Top)

A video surveillance device with multiple video inputs and one video output is called a multiplexer. Multiple security cameras are connected to it and their images can be presented on one monitor. A front panel displays the buttons that toggle each camera, and the signal from one camera or a combination thereof can be displayed. Multiplexers are simpler to use as compared with similar procedures on a DVR which normally requires a system login, operating a keyboard and controlling a mouse.

MUX (Back to Top)

A multiplexer.

N

N.T.S.C. (National Television Standards Committee. See E.I.A.) (Back to Top)

A Color TV system used in the USA.

N/D (Neutral Density) (Back to Top)

A filter that attenuates light equally over the whole visible spectrum.

Network Address Port Translation (NAPT) (Back to Top)

Network Address Port Translation is the official name for IP masquerade. This technology is used to effectively utilize scarce IP address resources by converting IP addresses and TCP/IP port numbers between two networks (WAN/LAN).

Network Address Translation (NAT) (Back to Top)

This technology makes it possible to mutually convert private and global lP addresses as well as transparently access these addresses. NAT functions are incorporated in a router.

Network Camera (Back to Top)

Also known as a Network IP Camera, this is a stand-alone camera that uses a standard web-browser to view live, full motion video from a computer network, including over the Internet. They often feature an embedded OS (operating system) and features like: FTP of images, web server capability, and built-in motion detection.

Network Time Protocol (NTP) (Back to Top)

NTP is a time information protocol that is used as a standard on the Internet. SNTP is a simplified version of NTP.

Noise (Back to Top)

Undesired signal(s) that corrupts the original video signal and may reduce image quality.

Neutral Density Filter (Back to Top)

This category of lens filter reduces light of all wavelengths in equal amounts.

NTSC (National Television Standards Committee) (Back to Top)

The NTSC represents the American and Japanese standard television video signal format of 525 picture lines and a 60Hz field frequency.

NVR (Network Video Recorder) (Back to Top)

Functionally similar to a DVR, a NVR also accepts IP camera inputs. NVRs can be software based, making them suitable only for accepting IP camera streams over the Internet.

O

Ohms (Back to Top)

These are units that measure the impedance or resistance of an electrical device.

OLE Control Extension (OCX) (Back to Top)

OCX is a software component based on OLE2.0. Although the correct term Is OLE control, the filename extension is "OCX", and therefore it is primarily referred to as OLE control extension. It is also called Active X.

Optical Filters (Back to Top)

These filters selectively allow for different frequency light to pass through.

OSI Reference Model (Back to Top)

This model shows the protocol guidelines and its functions are separated into a total of seven layers. The upper layer of the model, which is closest to human interface consist of three layers: the application layer the presentation layer and the session layer. The lower layer, which is used for transmission purposes, consists 0 four layers: the transport layer, the network layer, the data link layer and the physical layer.

Outdoor Camera Housing (Back to Top)

A protective shell for security cameras to be placed in outdoor environmental conditions, these housings typically include cooling fans for summer use and heaters for winter use. The heaters also eliminate fogging of the glass anytime this occurs.

Outdoor Dome Housing (Back to Top)

This housing is dome shaped for insertion of dome security cameras, is very tamper resistant, and allows for PTZ.

P

P.A.L. (Phase Alternate Line. See CCIR) (Back to Top)

Europe’s television video signal standard is known as PAL. PAL uses 625 picture lines and a 50Hz field frequency, and is incompatible with NTSC.

P.S.T.N. (Public Switched Telephone Network) (Back to Top)

Standard phone lines used to transmit fastscan pictures via modems.

Pan (Back to Top)

Side-to-side movement of a camera (on a horizontal axis).

Passive (Back to Top)

A non powered element of a system.

PCMCIA Card (Personal Computer Memory Card International Association) (Back to Top)

These storage devices resemble a credit card and are typically used to expand the hardware functionality of portable devices such as laptops. In video surveillance application, PCMCIA cards can be used with portable PCs to add real-time full motion video capture of live security video. When used with digital cameras, they provide portable storage and a method for saving and transferring photos between digital cameras and PCs.

Peak-To-Peak (Back to Top)

The amplitude difference between the most positive and the most negative excursions of a signal.

Pelco-D (Back to Top)

A protocol that is used to control PTZ security camera movement.

Peripheral (Back to Top)

An optional device that can enhance a CCTV system, for example, a multiplexer, VCR, photo printer, etc.

Personal Computer Memory Card International Association (PCMCIA) (Back to Top)

PCMCIA stands for Personal Computer Memory Card International Association and regulates cards and slots related to PC cards.

Phase Adjustable (See Line Lock) (Back to Top)

The ability to delay the line locking process, so as to align cameras fed from A.C. voltages on different phases.

Photocell (Back to Top)

Automatically switches on the infra-red lights when light levels fall to a preset level.

Pinhole Lens (Back to Top)

Lens used for applications where the camera/lens must be hidden. Front of lens has a small opening to allow the lens to view an entire room through a small hole in a wall.

PIN (Back to Top)

A Personal Identification Number assigned to a user. It is used either by itself or in conjunction with a card.

PIP (Back to Top)

Picture in picture.

Pixel (Back to Top)

Picture element. The smallest cell or area of a CCD chip capable of displaying detail on a screen. The greater the number of pixels, the higher the resolution.

PoE (Power over Ethernet) (Back to Top)

This abbreviation refers to a method of supplying power to an IP camera using Category 5 Ethernet cables over a physically wired LAN network.

Polarizer (Back to Top)

This filter eliminates light reflected from glass, water, and other surfaces, thereby minimizing unwanted visual glare affects from glass and other non-metallic surfaces.

Port Address Translation (Back to Top)

This technology is used to convert IP addresses and TCP / UDP port numbers between two networks (WAN / LAN) and effectively utilize scarce IP address resources. This is also referred to as IP masquerade or NAPT.

Port Number (Back to Top)

This is the upper layer process of an IP that accepts information from the lower layer. TCP an UDP network protocols are identifiers used to differentiate, between programs.

Post-Record (Back to Top)

Sometimes referred to as post-record time, this is a DVR's ability to record after a motion detection event has occurred. It records for a specified amount of time after the event has been triggered, even though the motion may have ceased.

Potentiometer (Back to Top)

This device measures voltage or a potential voltage difference by comparing it with a standard voltage. It can also change resistance by moving the contact point, and is used to record pre-set positions in both zoom lenses and pan tilt heads.

Power supply (Back to Top)

Most security cameras utilize 24V AC or 12V DC power supplies. A power supply is usually plugged into a regular electrical outlet or part of a centralized power supply.

PPP (Point-to-Point Protocol) (Back to Top)

Point-to-point Protocol is the primary method used in establishing a direct connection between two devices on a network (usually a computer and the Internet). It is a communication protocol between computers using one of several methods: usually TCP/IP, telephone lines, or ISDN.

Pre-Record (Back to Top)

This DVR capability will record video prior to motion being detected, then send to the disk as much prior video as memory allows and video of the motion itself.

Presets (Back to Top)

The pre-positioning of pan, tilt and zoom cameras by the use of potentiometers in the moving parts of the camera head. These allow the control equipment to store and move to a set reference point when the controller dictates or when an alarm exists.

Pressure mat (Back to Top)

Placed before doorways, gates, and other entrances, this device responds to pressure (usually being walked or stood upon) to either open doors or activate the surveillance camera trained on that area.

Progressive (Back to Top)

Since it scans all lines onscreen at once, 60 times per second, this type of scanning is used by computer monitors to minimize flickering. It is also better able to show movement, offering more detail and less ghosting than interlaced scanning.

Protocol (Back to Top)

This term refers to the rules of transmission. Protocol provides a definition of the procedures that should be followed when sending and receiving data.

PTZ Camera (Back to Top)

PTZ stands for Pan, Tilt, and Zoom. These cameras are usually remotely controlled by software or a joystick. PTZ cameras are used when active real time monitoring with the ability to point the camera’s viewing area to a specific action or event is desired.

PTZ controller (Back to Top)

The controller used to control PTZ camera movement, usually software or a joystick.

Q

Quarter Common Intermediate Format (QCIF) (Back to Top)

With QCIF, the resolution of CIF Is reduced in similar proportion by half and the resolution becomes 176 x 144 pixels. The number of pixels is one-fourth that of CIF and this format supports moving images at a data rate of up to 30 frames per second.

Quad (Back to Top)

A device that compresses up to four video signals and simultaneously displays the images onto one monitor.

Quality Level (Back to Top)

This is used for V.Networks JPEG images to determine to what extent the original image should be compressed. There are settings for either seven levels or three levels (high, medium and low). Quality level is closely related to image quality and the lower the degree of compression, the higher the image quality; however this also causes the volume of data in the image file to increase. The default setting is either "2" or "Medium".

R

R.F. (Radio Frequency) (Back to Top)

Signals with a repetition rate above audible range, but below the frequencies associated 4 With heat and light.

Rack Mount (19" Rack) (Back to Top)

An industrial standard housing 19" wide, its height is measured in units (U’s) of 1.75".

RAID (Redundant Array of Independent Disks) (Back to Top)

This is referred to as a RAID disk array and is a means by which multiple hard disks can be combined to be utilized like a single disk and reliability and processing speed can be increased. Although there are seven different types of RAID ranging from RAID 0 to RAID 6, only RAID 0.1.5 and combinations of these types are actually used.

Random Interlace (Back to Top)

A scanning technique commonly used in CCTV systems in which there is no external control over the scanning process. That is, there is no fixed relationship between adjacent lines and successive fields.

Range Finder (Back to Top)

Used to determine the focal length needed and what the picture will look like on the monitor. The user looks through the device and adjusts the range finder to the desired picture. Numbers on the outside of the range finder indicate the focal length needed

Raster (Back to Top)

The rectangular pattern of scanning lines upon which the picture is produced. The illuminated face of the TV monitor without the video information present.

Reflected Light (Back to Top)

The scene brightness or the light being reflected from a scene.

Remote Host (Back to Top)

A system where the main computer that controls the system is remotely located. It allows a single computer to control multiple systems.

Resolution (Back to Top)

Resolution is the scale used to express the degree to which a screen is clear or blurred. Both horizontal resolution and vertical resolution are indicated using actual numbers and are also employed as scales for representing camera performance. In fact, horizontal resolution is generally utilized to compare performance. It can be said that the higher the number the better the performance of the camera. Ordinarily, a televised TV broadcast with fairly good horizontal resolution has a resolution of around 330 TV Lines.

Real-Time Transport Protocol (RTP) (Back to Top)

This is a transmission protocol used for streaming playback of sound or images. In UDP-type protocols, for which packet-loss countermeasures, transmission time guarantees etc. are not implemented effective bandwidth and delay time are usually sent to the server via RTCP. The server adjusts the quality of the data to be sent via RTP according to the transmission status information it has received and then sends the data.

Roll (Back to Top)

A loss of vertical sync which causes the picture to move up or down on the TV screen.

Router (Back to Top)

A router is a piece of equipment facilitating the exchange of packets throughout LAN or WAN networks. It moves packets across a predetermined path to their destination by storing and forwarding the packets, and then determining their optimal path along the network. A router is hardware based, but can also include software.

Rs232 (Back to Top)

A commonly used computer serial interface.

RTP (Real-time Transport Protocol) (Back to Top)

The Internet Engineering Task Force (IETF) developed RTPs to specify audio and video signal management. It standardizes the packet formatting for both for easy synchronization and Internet delivery. Streaming media systems and video conferencing systems use RTP, while DVR systems rely on this protocol in the implementation of the remote view feature. Since it doesn’t specify how video surveillance playback is implemented, the data from different RTP based surveillance systems usually cannot interoperate.

RTSP (Real Time Streaming Protocol) (Back to Top)

This open standard for Internet streaming of audio and video is popular among DVR makers for remote viewing of live or stored security camera video over the Internet. RTSP controls the transmission of the data stream much the way a television remote controls the television. Like RTP, interoperability problems exist between different DVR systems.

S

S-Video (Back to Top)

Representing an improvement in quality over composite video, S-Video separates chrominance and luminance onto two different signal wires, resulting in better picture quality.

SAD (Sum of Absolute Difference) (Back to Top)

This acronym refers to a mathematical technique used in motion detection.

S.E.C.A.M. (See CCIR) (Back to Top)

Color TV system used in France.

S.V.H.S. (Super Video Home System) (Back to Top)

New format high resolution VHS video recorders, capable of giving greatly improved picture if all features are used. VHS compatible.

S/N Ratio (Signal To Noise Ratio) (Back to Top)

Measure of noise levels of a video signal; the hi