Siemens TFT - Manual (Page 209)

Glossary
16-7 © Siemens Building Technologies Group
Lux
Is an international unit of illumination. It is the amount of uniform
light falling on an area of 1 square metre and is measured in lumen
per sq metre.
Magnification Ratio
Is the ratio between the focal length of a lens and the focal length of
a standard angle lens. It indicates the magnification of the image on
the monitor as compared to the image seen by a standard angle lens.
Matrix Switcher
Is a type of switcher which allows a single input to be switched to
many outputs. Matrix switchers are used in large CCTV systems and
have many powerful features.
Mercury Vapour Lamp
Is a popular type of artificial light source which emits a blue-white
light. Used extensively for commercial lighting.
Microwave Links
Is a type of transmission medium in which video, data or audio is
modulated with a microwave frequency and then transmitted to a
receiver in a remote location over free space.
Mimic Panel
Is a panel which shows the layout of a site with the camera positions
highlighted. By interfacing it with a CCTV system, the operator can
switch any camera to the monitors from the mimic panel itself.
Minimum Scene Illumination
Is a specification shown in most camera data sheets and indicates
the minimum light required at the scene to provide a reasonable pic-
ture on the monitor.
Modem
Is derived from the term 'modulator -demodulator' and is used to
convert a digital signal into an analogue signal so that it can be
transmitted via the PSTN telephone network.
Modulate
A method in which a signal to be transmitted is mixed with a high
frequency carrier signal.
Motorised Controlled Iris
Is a type of iris control in which the iris motor is controlled from a
remote location, usually in a zoom lens.
Multi Core Cable
Is a type of cable which has many cores enclosed in one outer jacket.
In CCTV it is normally used to transmit control signals.
Multimode Cable
Is a cheaper type of fibre optic cable which allows a light beam to
travel by more than one path thus causing transmission distortion.
Multiplexing
Is a process whereby many cameras are switched frame by frame.
This frame switching can be used in applications like multi-viewing,
multi-recording etc.
Neutral Density Filter
Is a type of filter used with lenses which reduces light of all wave-
lengths equally.
Noise
Is an unwanted signal generated by every electronic component. The
noise in a video signal causes a grainy or snowy effect on the image.
NTSC
National Television System Committee is a colour television system
and the standard used in the USA and Japan. NTSC has 525 horizon-
tal scanning lines and 60 fields per sec.
Ohms
Is a unit for measuring resistance or impedance of any electrical
device.
Omni Directional Transmitter
Is a transmitter which sends the signal in all directions.
Optical Filter
Is a type of filter used in optics which selectively allows light of dif-
ferent frequencies to pass through.
Oscilloscope
Is a device which visually displays the wave form of any electrical sig-
nal on a screen. In CCTV, it is used in trouble shooting and making
adjustments of various components.
PAL
Phase Alternating Line is a colour television system and the standard
used in Western Europe, Australia, parts of Africa and Asia. PAL has
625 horizontal scanning lines and 50 fields per sec.
Persistence of Vision
The retina of the human eye retains an image for 40ms. This charac-
teristic is called “persistence of vision” and is used to make a picture
appear continuous by flashing images on the retina at a rate faster
than 24 images per sec.
Phase Adjustment
Is a camera adjustment used to synchronise all the cameras in the
system by altering the phase of the power supply.
Phase Angle
Is the angle at any point of the sine wave of an AC power supply and
varies between 0 to 360 deg over a cycle.
Phosphor
Is a material which is capable of emitting light. It is used in fluores-
cent lamps, monitors etc. The duration of the emission depends on
the type of phosphor.
Picture Tearing
Occurs when the horizontal sync pulses are distorted or lost and the
monitor is unable to latch on to them causing the horizontal lines to
be displaced in a random manner. This is seen as a tearing of the pic-
ture on the monitor.