The opening of the lens that controls the amount of light reaching the surface of the pickup device. The size of the aperture is controlled by the iris adjustment.

A lens one or more of whose elements has a non-spherical surface. Aspherical surfaces are shaped to reduce the spherical and other aberrations.

In general terms, a reduction in signal strength.

A system for detecting errors in color balance in white and black areas of the picture and automatically adjusting the white and black levels of both the red and blue signals as needed for correction.

An automatic sequential video switcher which has manual switches or buttons, which allow a single CCTV camera to be displayed on screen without sequential switching.

In display devices, the self-acting mechanism which controls brightness of the device as a function of ambient light.

The process by which the illumination incident upon the face of a pickup device is automatically adjusted as a function of scene brightness.

A term used to describe the relationship of the distance of the lens to the image device. This distance is critical to maintaining the proper depth of field through changing focal lengths and varying light conditions. The correct back focus is normally achieved by adjusting the image pick-up device on the camera itself.

A video signal converted to a balanced signal, usually to enable it to be transmitted along a 'twisted pair' cable. Used in situations where the cabling distance is too great and which would produce unacceptable losses in a coaxial cable.

A transformer that levels out impedance differences, so that a signal generated on to a coaxial cable can be transferred on to a twisted pair cable.

The number of cycles per second (Hertz) expressing the difference between the lower and upper limiting frequencies of a frequency band; also, the width of a band of frequencies.

Special test pattern for adjusting color TV receivers or color encoders. The upper portion consists of vertical bars of saturated colors and white. The power horizontal bars have black and white areas and I and Q signals.

The speed at which data is transmitted, i.e.. 1 baud = 1 Bit per second.

In a plane containing the direction of the maximum of a beam, the angle between the two directions in which the radiation intensity is one half the maximum value of the beam.

An adaptor with which a loose tube containing two optical fibres can be split into two single fibre cables. (See loose tube).

The amount of compressed video data delivered into the decoding system. The higher the bit-rate, the higher the quality and/or the resolution of the video. For optical disc formats, this is usually measured in megabits per second (Mbps).

The defocusing of regions of the picture where the brightness is at an excessive level, due to enlargement of spot size and halation of the fluorescent screen of the cathode-ray picture tube. In a camera, sensor element saturation and excess which causes widening of the spatial representation of a spot light source.

Sudden variations in picture presentation (brightness, size, etc.,) independent of scene illumination.

Device connecting two separate networks. Once bridging is accomplished, the bridge makes interconnected LANs look like a single LAN, passing data between the networks and filtering local traffic.

Also called burn. An image which persists in a fixed position in the output signal of a camera tube after the camera has been turned to a different scene or, on a monitor screen.

A topology network where all terminals are attached to a transmission medium serving as a bus.

Increases the video signal level by amplification, used on long cable runs to compensate for the loss in video signal level.

Term seen in video multiplexer terminology, represents one sixteenth of the area of a full screen.

The approximate size of a camera image pickup device. This measurement is derived from the diagonal line of a chip or the diameter of the tube. Currently there are five format sizes in the CCTV industry: 1", 1/3", 2/3", 1/4", and 1/5".

A service through which subscribers pay to have local television stations and other programs brought into their homes from the antenna via coaxial cable.

The 3.7 - 4.2 GHz (Gigahertz) frequency band is used for the distribution of programming by virtually all satellite/cable networks. There are 22 C-Band satellites in operation over North America today. They range in power from 5-11 watts per transponder, requiring receive antennas of 5-12 feet in diameter. Beginning in 1992, the fleet was gradually replaced with higher powered (10-17 watt) satellites. This allows the average size of a C-Band installation to be reduced to 90 inches in diameter.

Charge Coupled Device - a light sensitive imaging device for almost all cameras. Typical sizes for CCTV cameras - 1/2", 1/3", 1/4".

Committee Consultative International Radiocommunications. Monochrome Video Signal for most of Europe, Australia and the Middle East - 625 lines, 50Hz.

CCD. For imaging devices, a self-scanning semiconductor array that utilizes MOS technology, surface storage, and information transfer by shift register techniques.

The part of a colour video signal that carries the colour information.

The reference signal included in the video signal after the horizontal sync pulse. This enables a colour monitor to lock on to a colour composite video signal.

An optical defect of a lens which causes different colors or wave lengths of light to be focused at different distances from the lens. It is seen as color fringes or halos along edges and around every point in the image.

The color quality of light which is defined by the wavelength (hue) and saturation. Chromaticity defines all the qualities of color except its brightness.

That portion of the NTSC color television signal which contains the color information.

A color term defining the hue and saturation of a color. Does not refer to brightness.

(1) ( C ommon I ntermediate F ormat) A standard video format used in videoconferencing. CIF formats are defined by their resolution, and standards both above and below the original resolution have been established. The original CIF is also known as Full CIF (FCIF). The bit rates in the chart below are for uncompressed color frames.

(2) ( C ommon I mage F ormat) A standard frame size for digital video. Common Image Format, not to be confused with Common Intermediate Format in #1 above, defines 720x480 and 720x576 as the two standard SDTV frames.

(3) ( C ells I n F rames) A networking technology developed by Cornell University that allows ATM backbones to be used with Ethernet LANs. CIF utilizes the inherent quality of service in ATM, which allows for real-time voice and video, all the way to the Ethernet end station by placing the ATM cell within the Ethernet frame. It differs from LAN Emulation, in which Ethernet packets are encapsulated into LAN Emulation packets and then converted into ATM cells.

CIF is implemented by replacing the Ethernet hub with a switch or multiplexor known as a CIF Attachment Device (CIF-AD). CIF drivers are used in the client stations.

In Fibre Optics the outermost region of an optical cable, less dense than the central core, it acts as an optical barrier to prevent transmitted light leaking away from the core.

Name given in honor of Arthur C. Clarke, to the orbit 22,300 miles directly above the equator where satellites can maintain a stationary position in relation to the earth. Also called geostationary orbit.

An antenna comprised of an extension to the inner conductor of a coaxial line and a radiating sleeve which in effect is formed by folding back the outer conductor of the coaxial line.

A particular type of cable capable of passing a wide range of frequencies with very low signal loss. Such a cable in its simplest form, consists of a hollow metallic shield with a single wire accurately placed along the center of the shield and isolated from the shield.

A device which produces an NTSC color signal from separate R, G, and B video inputs.

Spurious colors introduced into the picture by the change in position of the televised object from field to field.

The degree to which a color is free of white or any other color. In reference to the operation of a tri-color picture tube it refers to the production of pure red, green or blue illumination of the phosphor dot face plate.

The degree to which a color is free of white light.

A signal used to establish and to maintain the same color relationships that are transmitted.

The transmission of a signal which represents both the brightness values and the color values in a picture.

A condition that appears on a VDU that is caused by near burn combined with image movement.

A signal containing Line and Field pulses, but one which has no video information.

A technique used by some video transmission systems. Once the first image has been constructed only the part of the image that changes is subsequently transmitted, allowing high speed updates when little movement is seen. However, the speed of update decreases with more movement.

A device which functions during the horizontal blanking or synchronizing interval to fix the level of the picture signal at some predetermined reference level at the beginning of each scanning line.

The shearing off of the peaks of a signal. For a picture signal. This effects the positive (white).

The combined picture signal, including vertical and horizontal blanking and synchronizing signals.

The crossover of the three electron beams of a three-gun tri-color picture tube. This normally occurs at the plane of the aperture mask.

That portion of the composite color signal, comprising a few cycles of a sine wave of chrominance subcarrier frequency, which is used to establish a reference for demodulating the chrominance signal. Normally approximately 9 cycles of 3.579545 MHz.

Extraneous colors appearing at the edges of colored objects, and differing from the true colors in the object.

The range of light to dark values in a picture or the ratio between the maximum and minimum brightness values. The ratio between the whitest and blackest portions of television image.

An undesired signal from a different channel interfering with the desired signal.

A relatively new industry standard for mounting a lens to a camera where a 1" X 32 thread is employed and the distance from the image plane from the shoulder of the lens is 12.52mm. A CS-mount lens may NOT be used on a C-mount camera.

Auto-iris lenses where the iris is controlled by the circuitry of the camera.

A type of low gain antenna consisting of two (often internal) elements.

An antenna having the property of radiating or receiving electromagnetic waves more effectively in some directions than others.

Electronic Iris - a feature of modern CCD cameras where the camera electronics automatically varies the shutter to mimic an AI lens, allowing the use of fixed or manual iris lenses in a wider range of areas.

Electrical Industries Association. Monochrome video signal for North America and Japan TV standard - 525 lines 60Hz,

The signal used for the synchronizing of scanning specified in EIA Standards RS-170, RS-330, RS-343, or subsequent issues.

Typically an antenna that is enclosed into a product's housing or case, or one that is not readily discernible by a casual observer. The antenna forms an integral, inseparable part of the product.

Electro Magnetic Interference - electrical or electromagnetic energy that may cause unwanted responses, degradation or failure in electronic equipment.

An electronic circuit that introduces compensation for frequency discriminative effects of elements within the television system, particularly long coaxial transmission systems.

The most widely used LAN transmission network. Based on a bus network topology, it runs at a maximum speed over 100 meters of 10Mbit/s. It operates over conventional co-axial cable, thin wire co-axial cable and unshielded twisted pair cabling. This has several implementations - 10Base5 for use over conventional co-axial cable, 10BaseF for use over optic fibre, and 10BaseT for use over Unshielded Twisted Pair (UTP) cabling.

Includes specifics such as DVR recordings set at a resolution rate so that faces, number plates etc. can be identified, and accurate time and date information displayed with each recording.

Sony Chipset type that offers very good images in both day and night time. Typically, cameras with Ex-View chipset have good Low Light (LUX) levels.

The ability of electronic equipment (normally seen in cameras) to accept a synchronisation signal from an external source and synchronise itself to it.

Various size spacers used between the camera and lens to reduce the Minimum Object Distance. Not recommended for use with zoom lenses due to the loss of tracking ability.