Product guide

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Frame Relay
Packet-switched network similar to X.25 but with end-to-end err
or-
checking and high-speed transmission rates.
Frame Stor
e
Digital information store capable of holding a complete frame of
video infor
mation.
Frame T
ransfer CCD
T
ype of CCD chip which consists of vertical charge transfer channels
placed side by side. During vertical blanking, the charge generated
in the light sensitive imaging ar
ea is rapidly transferred into a shielded
storage area. During the horizontal blanking, this charge is shifted
down a line at a time into a horizontal shift r
egister where it is clocked
out during each line period to form the video signal.
Full Pictur
e Update
The technology which enables a transmission system to update a high
quality full pictur
e on each picture refresh at very fast speeds.
Galvanometric (galvometric)
One method of converting the small electric currents produced by
Auto Iris cir
cuits into physical movement of the iris diaphragm. Used in
both Auto Iris and Direct Drive lenses.
Gamma
A camera adjustment that ensures a linear correlation of light gain on
the entir
e system eg. A doubling of light input gives double light
output.
Gateway
A computer that performs protocol conversation between different
types of networks or applications.
Gen. Lock (see ext. sync)
T
o synchronize one piece of equipment to the sync pulses of another.
Gigabit Ether
net
Technology that adapts the Ethernet model for data transmission at 1
Gbps or higher.
Ground Loop
An unwanted continuous or temporary ground current flowing back
and forth between two devices that are at different ground
potentials.
Hard Disk
Non volatile digital data storage device used in PCs. Come in various
storage sizes, normally measured in giga-bytes. See Hard Disk
Recorder.
Hard Disk Recorder - HDR (Digital Video Recorder - DVR)
Device that uses digital techniques to r
ecor
d CCTV pictures to a hard
disk. The results can be of higher quality than VHS or SVHS, events can
be found faster and there is no loss of quality when copies are made.
Har
dwir
ed
Method of contr
olling camera points using multicore cable.
Hot Swapping
Removing and replacing a component of a larger system while the
system is r
eceiving power and operating.
HTML (Hypertext Mark-up Language)
A standar
d for defining documents with hypertext links. HTML is a
subset of SGML (Standar
d Generalised Mark-up Language) and is
used to establish links between documents on the World Wide Web.
HTTP (Hypertext Transfer Protocol)
The clients/server protocol used for connections to servers on the
World Wide Web. Addresses of Web sites begin with an http://prefix.
Hub
A central connecting device in a network that joins communications
lines together in a star configuration.
Hz (Hertz)
Cycles per second.
I.R. (Infra Red)
A range of frequencies lower than visible red light used for covert
surveillance or as a low cost wir
eless video link.
Ident
Number or title super-imposed on a video signal.
Image Sensor For
mat
Size of the CCD element in the camera.
Impedance
The ef
fective resistance of an electronic circuit to an A.C. signal.
Interlace (2:1 interlace)
The accurate combining of two fields, one odd one even, into a
single frame.
Interleaving
Method used with alar
ms or activity detection which allows extra
frames of video from alarmed cameras to be added to a time
multiplexed sequence whilst a state of alar
m exists.
Interline T
ransfer CCD
T
ype of CCD chip in which the photosensors acquire and store an
electric charge according to the intensity of light falling on them. The
char
ges are first transferred to a vertical shift register and then a
horizontal shift register. This is controlled by an external pulse timing
system.
Internal Sync (crystal controlled)
A camera that generates its sync pulses without r
eference to any
other source. Normally using a crystal controlled oscillator.
Internet
1) Any large network made up of several smaller networks.
2) A group of networks that are interconnected so that they appear
to be one continuous large network and can be addressed
seamlessly at the OSI Network layer through routers.
3) The industry name for the Worldwide interconnected network.
Based upon the original ARPANET network, it's used as a reference
resource, a way of sending e-mail and an online chat room for users
around the world.
Intranet
A network connecting a related set of standard Internet protocols
and files in HTML format with employees using Inter
net browsers in an
organisation's network and within the corporate firewalls.
IP (Internet Protocol)
The protocol used in gateways to connect networks at the OSI
Network Layer (Layer 3) and above. IP r
outes a message acr
oss
networks.
Iris (Iris diaphragm)
Adjustable diaphragm that r
egulates the amount of light passing
through a lens.
ISDN (Integrated Services Digital Network)
A digital switched network used to transmit voice, data, images or
video. Also see BRI
J-PEG
Joint Pictur
e Expert Gr
oup. A popular suite of digital compr
ession
tools. Originally for use with "still" pictur
es but often used in CCTV
products.
Kb
Kilobyte, or one thousand bytes or characters of information.
Kilo
Order of magnitude; 10 3
LCD
Liquid Crystal Display. A type of flat screen display.
Lens Calculator Software
A computer program for specifying correct lenses.
Glossary of T
er
ms