Siemens TFT - Manual (Page 210)

Glossary
16-8 © Siemens Building Technologies Group
16
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.
RS-232
Is a communication protocol used for communication between
microprocessor based devices.
S-VHS
Super VHS is a type of video format in which the illuminance and
chrominance signals are sent separately resulting in improved pic-
ture quality.
Salvo Switching
Is a feature in matrix switchers. On command from the matrix
switcher or an alarm event, a group of cameras can be switched
simultaneously onto a group of monitors.
Screen
Is a copper braid which covers the dielectric and centre core of a
coaxial cable.