Product guide

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Glossary of Terms
Chrominance (C)
The part of the video signal corresponding to the colour information.
Co-Axial Cable
Any cable that has a conductor and shield sharing the same axis.
Composite Sync
A signal comprising of both Line and Field sync pulses but without any
video infor
mation.
Composite V
ideo
The full video signal, including both video data and sync pulses.
Compr
ession
A number of methods to r
educe the size of digital information. See J-
PEG, M-PEG and Wavelets.
Conditional Refresh
Technique used in slow and fast scan where only small screen
changes are transmitted. Up to a certain percentage of the on-
scr
een picture can be updated before a full picture is required.
CS Mount (Special C mount)
New standar
d for connecting cameras and lenses. It has a shorter
penetration into the camera, needed for many moder
n CCD designs.
CS to C Mount Adaptor (C Ring)
5mm spacer ring used to enable the use of C mount lenses on CS
mount cameras.
D.D. (Direct Drive)
An Auto Iris lens requiring a D.C. reference from the camera rather
than the traditional video reference.
Daisychain
To connect devices in a series, one after the other where the
transmitted signals go to the first device, then to the second and so
on.
Data cable
Cable used for transmitting low level signals between system units.
dB (decibel)
A logarithmic unit for comparing two voltages, each 6dB doubles the
voltage.
Default
An assumption made by the system when no specific choice is given
by the programme or the user.
Depth of Field
The area of acceptable focus of an image. The wider you set the
aperture of a lens the lower the depth of field becomes.
Digital
A signal that levels ar
e r
epr
esented by binary numbers. These can be
kept in a stor
e.
Digital Video Recorder - DVR
See Hard Disk Recorder.
Distribution Amplifier
A device that accepts a video signal and sends it out over a number
of independent outputs.
DOS
A disk operating system in which programmes are stored on disk.
Duplex (Multiplexer)
A multiplexer with two frame stores allowing it to show multi-screen
pictur
es while per
for
ming time multiplex r
ecor
ding.
DVD (Digital Video Disk, Digital V
ersatile Disk)
A de facto standard agreed on by the computer, consumer
electronics and entertainment industries for storing 4.7 or more GB of
data on a single optical disc the size of a CD.
Dwell Time
The length of time a switcher will hold a camera before moving on to
the next in sequence.
E.I. (Electronic Iris)
Automatically varies a CCD camera's shutter to mimic Auto Iris
contr
ol, allowing fixed or manual iris lenses to be used in a wider range
of ar
eas.
EIA (Electronic Industries Association)
A standar
ds organisation in the US specialising in the electrical and
functional characteristics of interface equipment.
Encoded
The result of transferring information in a coded form to a medium.
Ethernet
A local ar
ea network (LAN) developed by Xerox, Digital Equipment
Corp. and Intel. Standardised as IEEE 802.3 and ISO 8802.3. Ethernet
connects up to 1024 nodes at 10 Mbps over twistedpair
, coax and
fibr
e optic cable. When a station is ready to send, it transmits its data
packets onto the network, which is common to all nodes. All stations
"hear" the data. The station that matches the destination addr
ess in
the packet responds while the others do nothing. Ethernet is a data-
link pr
otocol and functions at the Physical and Data-link Levels of the
OSI model (Layers 1 and 2).
Ethernet Address
A unique 48-bit number maintained by the IEEE/ISO and assigned to
each Ether
net network adaptor.
Event
Valid transactions reported by Access Control and Monitoring
Systems.
Ext. Sync (external sync)
The ability of CCTV equipment, normally cameras, to accept one or
more of the standard sync formats so as to align itself to the rest of the
system.
EXview™
The latest interline CCD sensor fr
om SONY that has increased sensitivity
across the visible spectrum and the near IR.
Fast Ethernet
Generally refers to 100BASE-T and 100BASE-FX but may also include
100VG.
Field
One half of a frame, consisting of either the odd or the even
numbered lines, 50 fields are transmitted every second.
Field of View
The view achieved with a particular lens; varies with the focal length.
Firewall
A network node set up as a boundary to pr
event unauthorised traf
fic
from one segment to cross over to another. Firewalls are used to
improve network traffic, as well as for security purposes.
Flash memory
A memory chip that holds its content without power but must be
erased in fixed blocks rather than single bytes. Block sizes typically
range from 512 bytes up to 256KB.
Focal Length
Of a lens, the distance in millimetres, between its secondary principal
point and its focal point. The higher the number the greater the
magnification and the less the field of view.
Focal Point
The point on the axis of a lens to which parallel rays of light will cover
.
Format
How the computer arranges the infor
mation onto disk. Can also apply
to printers.
Frame
One complete TV pictur
e made up of approximately 625 lines. 25
frames are transmitted every second.