Glossary
Pincushion Distortion
Is a type of distortion caused due to non uniform scanning in the monitor which makes the picture to bulge inward.
Pinhole Lens
Is a lens with a small diameter used for covert surveillance.
Pixel
(picture element) is the basic unit of a CCD chip which accumulates charge depending upon the amount of light falling upon it. A typical CCD chip has over 300,000+ pixels.
Polarizing Filter
Is a type of filter which reduces glare by intercepting reflected light from surfaces like water, glass etc.
Polycarbonate
Is a type of toughened glass which can be used in housings for use in areas of high vandalism.
Polyethylene
Is a type of plastic used to make outer jackets for cables.
Potentiometer
Is an electronic component in which the resistance can be changed by a movable contact point. It is used in pan tilt heads and zoom lenses to record preset positions.
Power Line Interference
Is a type of interference caused by main power lines and usually seen as horizontal bands on the monitor.
Preamplifier
Is a type of amplifier used to increase the output of a low level source allowing the signal to be processed by other devices.
Preset
Is a term used in CCTV to define pre determined position of a pan and tilt head and zoom lens.
Primary Colour
Is a colour which cannot be obtained by mixing other colours. Red, green and blue are the three primary colours which can be mixed to produce other colours.
PSTN
Public Switched Telephone Network is an analogue telephone net- work currently in use all over the world.
PTZ Controller
Is a device used to control the movement of the pan tilt head and zoom lens from a remote location.
Quad
Is a device which used to display pictures from 4 cameras on a single monitor.
Read Out Time
Is the time taken to read the charge from the pixels in a CCD chip.
Real Time Video
Is a picture with more than 24 frames per sec and therefore looks continuous.
Receiver Driver
Placed at the camera point and connected by either a coaxial or twisted twisted pair cable. It is used to decode the incoming control signals for the Pan, Tilt and Zoom functions.
Reed Switch
An alarm is activated when the reed switch is opened or closed. It is widely used with doors, windows, roller shutters etc and can be used to activate equipment to bring the nominated camera up for extended viewing.
Regulated Power Supply
DC power supply in which the ripple factor is minimal.
Remote Head Camera
In this type of camera, the CCD chip is separated from the camera body by cable. It is used in applications where the amount of space available to fit the camera is limited.
Resolution
A measure of picture definition and clarity and is represented by the number of lines. Greater the number of lines, higher the resolution.
RG-11
Coaxial cable with a thicker centre core and used for transmission of video signals up to 500m.
RG-59
Coaxial cable used for transmission of video signals up to 250 m. It is probably the most popular cable used in CCTV.
Ripple Factor
Is the amplitude variation present in a DC power supply due to insuf- ficient filtering. A large variation can damage a DC camera.
Is a communication protocol used for communication between microprocessor based devices.
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Super VHS is a type of video format in which the illuminance and |
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chrominance signals are sent separately resulting in improved pic- |
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ture quality. |
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Salvo Switching |
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Is a feature in matrix switchers. On command from the matrix |
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switcher or an alarm event, a group of cameras can be switched |
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simultaneously onto a group of monitors. |
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Screen |
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Is a copper braid which covers the dielectric and centre core of a |
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coaxial cable. |
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© Siemens Building Technologies Group |
