Siemens TFT - Manual (Page 206)

Glossary
16-4 © Siemens Building Technologies Group
16
Crimping
Is a process of connecting a cable to a connector without screwing or
soldering using a special tool. In crimping a BNC connector, the cen-
tre pin of the connector is uniformly pressed against the cable core.
To ensure a proper connection, a good crimping tool is needed.
Cross Talk
Is the noise generated by the interference between adjacent (in
terms of signal frequency) video, audio or data channels in a multi-
plexed signal.
CS-Mount
Is a lens mount with 12.5 mm back flange. The back flange is the dis-
tance between the lens mounting surface and the CCD chip. Cameras
with CS-mount need a special adapter ring to be used with C-
mounted lenses (supplied with every camera).
DC
Direct current
Decibels
Is a logarithmic ratio used to compare characteristics of electrical sig-
nals.
De-multiplexing
Is the process of separating the different video, audio or data chan-
nels which were multiplexed at the source.
Depth of Field
Is the distance between the nearest and furthermost points of the
scene which appear in sharp focus. It is dictated by the F-stop and
focal length of the lens.
Dielectric
Is a material which insulates the solid centre core of a coaxial cable
from the screen. The thickness of the dielectric affects the impedance
of the cable.
Dome
Is a type of camera kit, inside a housing made of smoked or tinted
plastic. It is excellent for discreet surveillance and is supplied with
inbuilt pan tilt heads and zoom lens mechanisms.
DSP Chip Digital Signal Processing Chip
Is a solid state device which converts an analogue video signal into a
digital video signal. It is used in digital cameras and also in computers
to digitise video images.
Duplex
Is a system which can handle simultaneously two channels of video,
audio or data signals.
Dwell Time
Is a feature in a switcher. It is the time period a picture from a given
camera remains on the monitor before being replaced by a picture
from the next camera. Switchers may have fixed or programmable
dwell times.
EASS Electronic Surveillance System
It is used in retail shops to electronically tag the article merchandise to
prevent shop thefts. A CCTV system can be interfaced with an EASS
system so that the appropriate camera is switched on when an of-
fence occurs.
EIA
Is a scanning method specified by the Electrical Industry Association.
RS-170 is the standard for monochrome and RS-170A is the standard
for colour.
Electrical Filter
Is a type of electrical circuitry designed to limit transmission of cer-
tain frequencies.
Electron Beam
Is a concentrated flow of electrons in a nominated direction.
Electronic Shutter Speed
See Shutter Speed.
Shutter Speed
Is the speed at which the charge is read out from the CCD chip. The
factory setting is 1/50 sec (PAL) or 1/60 sec (NTSC) and can be
increased up to 1/100,000 sec depending upon the camera brand. It
can be changed by using dip switches or in some cases by the inbuilt
menu in the camera.
EMI Electro Magnetic Interference
Is interference which is usually caused by any electrical equipment
radiating electro magnetic frequencies.
Ergonomics
Is the study of man, machine and the environment to achieve maxi-
mum efficiency.
Event Recorder
Is a type of recorder that is normally maintained in pause mode and
starts recording only when activated by an alarm.
Extruded Aluminium
Is aluminium processed through a die and shaped for use to construct
housings for CCTV applications.
Extruded Plastic
Is a process in which smoked or tinted plastic is processed and shaped
to construct dome housings.
F-stop
Is the ratio between the focal length of the lens and the effective
diameter of the iris opening. It indicates the light gathering ability of
the lens.
Fence Protection System
Is a type of sensor installed on or around the perimeter fence in a site
to detect any intrusion. There are many types of fence protection sys-
tems available. In CCTV it can be interfaced with a switcher or similair
piece of equipment to switch a nominated camera for extended view-
ing.