Specifications
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GLOSSARY OF TERMS
SCSI (Small Computer Standard Interface) - A hardware bus interface
that enables a single expansion board in the computer to be connected
to up to 7 or 15 peripheral devices (hard disk, CDROM, scanner, etc).
SDN (Software Day/Night) - Colour Mono with no fixed IR cut filter.
SECAM (Systeme Electronique Couleur Avec Memoire. See CCIR) -
Colour TV system used in France.
Sens-Up - This feature is programmable and slows down the shutter
speed in monochrome mode for brighter pictures in extremely low light
levels.
Sensitivity - A camera’s ability to reproduce a given scene with a given
amount of light. Usually expressed in lux.
Serial Transmission - Method of data transmission in which the bits of
a data character are transmitted sequentially over a single channel.
Server - In general, a server is a computer programme that provides
services to other computer programmes in the same or other
computers.
Shutter - An electronic circuit available on many CCD cameras. Allowing
the light gathering period (1/50th of a second) of the camera to be
stopped prematurely (as little as 100,000 of a second).
SIA (Security Industry Association) - Also describes a signalling protocol.
Single-Mode Fibre - An optical fibre that supports only one mode of
light propagation above the cut off wavelength. The core diameters are
usually between 5 and 10 micrometres.
Smear - An unwanted side effect of vertical charge transfer in a CCD
chip. It shows as vertical white (or sometimes red) stripes in parts of the
image where there are very bright highlights. In some modern chip sets
smear is minimised to almost undetectable levels.
SMTP (Simple Mail Transfer Protocol) - SMTP is used for sending and
receiving e-mail.
S/N Ratio (Signal to Noise Ratio) - Measure of noise levels of a video
signal; the higher the number the better.
Spot Filter - A small insert used in a lens to increase the F-stop range
of the lens.
SSAIB - Security Systems and Alarm Inspection Board.
Switch - A switch is a network device that connects network segments
together, and which selects a path for sending a unit of data to its next
destination.
Swivel Mount - Used on a tower or bracket to enable the housing to be
pointed at any angle, vertically or horizontally.
Sync (Synchronisation Pulses) - Pulses generated, normally by the
camera, to tell other pieces of equipment when a picture (field sync) or
one line of a picture (line sync) is to start.
TCP/IP - TCP is used along with the Internet Protocol (IP) to transmit
data as packets between computers over the network.
TDN - True Day/Night colour monochrome operation with switching IR
cut filter.
Tearing - A term used to describe a picture condition in which groups of
horizontal lines are displaced in an irregular manner.
Telnet - Telnet is a simple method with which to access another network
device, e.g. a computer.
Terminated (75Ohm terminated) - Video input of a piece of CCTV
equipment, wired to be the last in a particular video line.
Telemetry - A system utilising ‘control code’ transmitters and receivers.
These use the video cable or a simple twisted pair cable to send their
information.
TFT (Thin Film Translator) - A type of flat screen display.
Token Ring - A network-access mechanism and ring topology in which a
supervisory frame or token is passed from station to station as a poll for
network transmission (IEEE 802.5 standard).
Triplex™ - Feature that gives you the ability to simultaneously view
both playback and live cameras within the same multi-screen, while still
encoding.
TVL (Television Lines - Resolution) - The maximum number of changes
between light and dark on a picture across 3/4 of the width dictates the
resolution of a CCTV product, measured in TVL.
Twisted Pair - A cable, often screened, that consists of two conductors
twisted together along their length.
UDP (User Datagram Protocol) - UDP is a communications protocol that
offers limited service for exchanging data in a network that uses the
Internet Protocol (IP).
Unicast - Communication between a single sender and a single receiver
over a network.
UNIX - An operating system originally designed by AT&T for multi-users
applications. Other versions include AIX, XENIX and LINUX.
Unterminated (Hi-Z) - Video input of a piece of CCTV equipment, wired
so as to allow the video signal to be fed to further equipment. Does not
necessarily include extra sockets for the extra coaxial cables.
Update Rate - The number of pictures (fields) per second recorded by
timelapse VCRs/Multiplexers or HDRs.
UPS (Uninterruptible Power Supply) - These are power supplies used
in the majority of high security systems, whose purpose is to back-up
the system when the mains power fails. The duration of this depends
on the size of the UPS, usually expressed in output VA (or kVA), and
the hold up time expected from fully charged batteries. There are two
common types, “off line” and “on line”. Off line uses a switch to change
from mains to battery operation, thus there can be a short break in the
output. On-line UPSs are a type where the converter is always working;
hence there is no switch over break at the output.
URL (Uniform Resource Locator) - An “address” on the network.
URN (Unique Reference Number) - As issued for each security system
by the Police.
USB (Universal Serial Bus) - A plug-and-play interface between a
computer and peripheral devices (scanners, printers etc).
USB 2.0 - Also referred to as Hi-Speed USB, USB 2.0 is an external
bus that supports data rates up to 480Mbps. USB 2.0 is an extension
of USB 1.1. USB 2.0 is fully compatible with USB 1.1 and uses the same
cables and connectors. Hewlett-Packard, Intel, Lucent, Microsoft, NEC
and Philips jointly led the initiative to develop a higher data transfer rate
than the 1.1 specification to meet the bandwidth demands of developing
technologies. The USB 2.0 specification was released in April 2000.