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Glossary - C
CAD stands for Computer Aided Design. This is where designs are done on computer by specialialized software.
[cd]. A unit for measuring luminous intensity. One candela is approximately equal to the amount of light generated by an ordinary candle. Since 1948 there has been a more precise definition of a candela which is: the luminous intensity of a black body heated up to a temperature at which platinum converges from a liquid state to a solid.
- CAT 5
- Category 5 cable, commonly known as Cat 5, is a twisted pair cable type designed for high signal integrity. Category 5 cable includes four twisted pairs in a single cable jacket. Category 5 has been superseded by the Category 5e specification
- CAT 5e
- Cat 5 e cable is an enhanced version of Cat 5 that adds specifications for far end crosstalk.
Community Antenna Television
- CCD Aperture
The proportion of the total area of a CCD chip which is photosensitive.
Stands for Charge Coupled Device, which is the new age imaging device, replacing old tubes. When first invented in the 1970's, it was initially intended to be used as a memory device.
Commitee Consultatif International des Radiocommunique, or in English, Consultative Committee for International Radio, which is the European standardisation body that has set the standards for television in Europe. It was initially monochrome, therefore today the term CCIR is usually used to refer to monochrome cameras which are used in PAL countries.
- CCTV Camera
A unit containing an imaging device which produces a video signal in the basic bandwidth
- CCTV Installation
A CCTV system, or an associated group of systems, together with all necessary hardware, auxiliary lighting, etc., located at the protected site.
- CCTV system
An arrangement comprising of a camera and lens with all ancillary equipment required for the surveillance of a specific protected area.
Closed Circuit Television - a Television system intended for only a limited number of viewers, as opposed to Broadcast TV.
Stands for Closed Circuit Video Equipment, an alternative acronym for CCTV
Compact Disk. A standard media as proposed by Philips and Sony, where music and data are stored in digital format.
Compact Disk Read Only Memory. The total capacity of a CD-ROM when storing data is 640MB.
Correlated Double Sampling. A technique used in the design of some CCD cameras that reduces the video signal noise generated by the chip.
Colour Filter Array is a set of optical pixel filters used in single chip color CCD cameras, in order to produce the colour components of a video signal.
The color information of a color video signal.
Commission Internationale de l'Eclairage. This is the International Committee for Light, established in 1965. It defines and recommends light units.
The outer part of a fibre optics cable, which is also a fibre but with a smaller material density that the centre core. It enables a total reflection effect so that the light transmitted through the internal core stays inside.
The first standard for CCTV lens screw mounting. It is defined with the thread of 1"(2.54mm) in diameter and 32 threads/inch, and the back flange-to-CCD distance of 17.526mm. The C-mount description applies to both: lenses and cameras. C-mount lenses can be put on both, C-mount and CS-mount cameras, only in the latter case an adaptor is required.
- Coaxial Cable
The most common type of cable used for copper transmission of video signals. It has a coaxial cross-section, where the centre core is the signal conductor, whilst the outer shield protects it from external electromagnetic interferences.
- Colour carrier
The sub-frequency in a colour video signal(4.43 MHz for PAL) which is modulated with the colour information. The colour carrier frequency is chosen so as to have its spectrum interleave with the luminance spectrum with a minimum interference.
- Concave lens
This is a lens that has negative focal length, ie. the focus is virtual and it reduces the objects.
A common term used in reference to the video picture dynamic range, ie. the difference between the darkest and the brightest parts of an image.
- Convex lens
A convex lens has a positive focal length, ie. the focus is real. It is usually called a magnifying glass, since it magnifies the objects.
Stands for Cathode Ray Oscilloscope (see Oscilloscope)
A type of interference caused by audio frequencies from one line being coupled into adjacent lines.
A newer standard for lens mounting. It uses the same physical thread as the C-mount, but the back flange-to-CCD distance is reduced to 12.5mm in order to have the lenses made smaller, more compact and less expensive. CS-mount lenses can only be used on CS-mount cameras.
Composite Video Bar Signal. In broadcast television this refers to the video signal itself, including the colour information and syncs.