Glossary
of Terms
A
AC Adapter
Alternating Current Adapter; when plugged to AC Power
(usually 117VAC/60Hz in the United States) it produces
12VDC, 24VAC or others. "UL Listed" and "Regulated"
recommended. It is also called Power Transformer.
AC Power
Alternating Current Power. In the United States, the standard
AC Power is single-phase 117VAC/60Hz and is provided from
power outlets in the house. 24V AC power can be produced
from an AC Adapter.
AGC (Automatic Gain Control)
Automatically adjusts the video quality in low light condition.
Alarm Sensor
Like Video Motion Detector, detects changes of motion
to produce an alarm.
ALC (Automatic Light Control)
Allows the auto-iris circuitry to either take bright spots
more into consideration (peak), bringing out detail in
bright areas, or less into consideration (average) bringing
out detail in shadows. Select this mode when an auto-iris
lens is used.
Algorithm
A procedure or formula for solving a problem.
Analogue (Analog)
Continuously variable numerical values such as voltage,
current, etc. camera produces analogue video signals.)
Angle of View
The scene angle that a video camera lens can show on the
monitor, like Diagonal Angle, Horizontal Angle and Vertical
Angle, usually described in degree.
ANSI
American National Standards Institute. This organization
is responsible for approving U.S. standards in many areas,
including computers and communications.
Aperture
The light gathering area of a lens, controlled by the
iris.
ARP
Address Resolution Protocol; for mapping an IP address
to a physical machine address.
ASCII
American (National) Standard Code for Information Interchange.
A standard character-to-number encoding widely used in
the computer industry.
ASIS
American Society for Industrial Security.
Aspect Ratio
The ratio of the vertical to the horizontal image size;
3:4 is the NTSC standard.
Aspherical Lens
A lens designed with a non spherical shape so that it
passes more lights or decreases barrel distortion on wide
angle lenses.
Attenuation
A decrease or loss in a signal, usually measured in decibels.
Auto-focus Lens
Automatically adjusts the lens focus from surrounding
scene and keeps a moving object in focus.
Automatic Gain Control (AGC)
Automatically adjusts the video quality in low light condition.
Automatic Iris (Auto-iris)
A diaphragm device in the lens that adjusts to light level
changes. The iris diaphragm opens or closes the aperture
to control the amount of lights coming through the lens.
Automatic Level Control (ALC)
Allows the auto-iris circuitry to either take bright spots
more into consideration (peak), bringing out detail in
bright areas, or less into consideration (average) bringing
out detail in shadows.
Auto Terminating
Automatically select the correct termination depending
on whether the video output is connected.
Auto White Balance (AWB)
Automatically adjusts a color camera's color to maintain
white areas.
B
Bandwidth
The capacity of the transmission medium stated in bits
per second or as a frequency. Or, the amount of data that
can be transmitted in a fixed amount of time. For digital
devices, the bandwidth is usually expressed in bits per
second(bps) or bytes per second. For analog devices, the
bandwidth is expressed in cycles per second, or Hertz
(Hz).
Back Light Compensation (BLC)
Electronically compensates for high background lighting
to give detail which would normally be silhouetted.
Baud
A unit of measurement that denotes the number of bits
that can be transmitted per second. For example, if a
modem is rated at 9600 baud it is capable of transmitting
data at a rate of 9600 bits per second.
Bifocal Lens
A lens system that has two different focal length lenses
and images two identical or different scenes onto a single
camera sensor. The two captured scenes appear as a split
image on the monitor.
Binary
A numbering system with only two values: 0 (zero) and
1 (one).
Bit
Abbreviated with small "b". Binary Digit. The
smallest unit of data in a computer.
Blanking
The process whereby the beam in a CRT is cut off during
the retrace period.
BLC (Back Light Compensation)
Electronically compensates for high background lighting
to give detail that would normally be silhouetted.
BNC
Bayonet Neil-Concelman or British Naval Connector. A connector
widely used in the CCTV industry, usually for coaxial
cable. Easy to install and reliable with little video
signal loss. Pictures of BNC Connectors
bps
Bits Per Second is the unit used for measuring line speed,
the number of information units transmitted per second.
Brightness Control
The manual bias control on a cathode ray tube or other
display device that controls the average brightness and
the contrast of a picture.
Browser
An application program that provides a way to look at
and interact with all the information on the World Wide
Web. Netscape and Microsoft Internet Explorer are the
two browsers that vast majority uses.
Byte
Abbreviated with capital "B". A unit of data
that is eight bits long and is used by most computers
to represent a character such as a letter, number or symbol.
C
C-Mount
An industry standard for lens mounting. C-Mount is 1-inch
diameter with 32 threads per inch. A C-Mount lens needs
C-ring when it is mounted at a CS-Mount camera.
C-MOS
Complementary - Metal Oxide Semiconductor. A video image
sensor chip that produces much lower quality picture than
CCD chip.
Camera Format
Video camera's CCD chips format; 2/3", 1/3",
1/4", etc.
CATV
Cable Access Television.
CCD
Charge Coupled Device. A video image sensor chip.
CCIR
International Radio Consultative Committee; has made the
technical recommendation for the European 625 line standard
for video signals.
CCTMA
Closed Circuit Television Manufacturers Association.
CCTV
Closed Circuit Television. It does not broadcast TV signals
but transmits them over a closed circuit through electrically
conducting cable or wireless transmitter and receiver.
CCTV Camera
A part of the CCTV system that captures the video pictures.
CCTV Monitor
A part of the CCTV system that receives the video pictures
from a CCTV camera and displays them.
Coaxial Cable
A cable that can carry a wide range of frequencies with
very low signal loss. It consists of a metallic shield
with a single wire placed along the center of a shield
and isolated from the shield by an insulator.
Color Saturation
The degree of mixture of a color and white. High saturation
means little or no white.
Composite Video Signal
A combined signals in a television transmission. The picture
signal, blanking signal, and vertical/horizontal synchronizing
signals are all combined.
CRT
Cathode Ray Tube. The vacuum tube part of a monitor or
television.
CS-Mount
An industry standard for lens mounting. CS-Mount is 1
inch diameter with 32 threads per inch. A C-Mount lens
needs C-ring when it is mounted at a CS-Mount camera.
D
Date/Time Generator
Installed between a CCTV camera and a monitor, it generates
the information of Date, Time and camera ID.
DC Power
Direct Current Power; can be derived from an AC adapter
or from a battery. Among DC voltages of 6, 9, 12, 24,
28, 12VDC is most common in the CCTV industry.
Decibel (dB)
The power or voltage ratio of two signals.
DIP switches
Dual Interface Poll switches usually allow you to change
the configuration of a circuit board to suit your application.
DMZ
Detection of Motion Zone
DHCP
Dynamic Host Configuration Protocol; lets network administrators
manage centrally and automate the assignment of IP addresses
in an organization's network.
DIN
Multi-wire cable with DIN connectors at both ends. Usually
has 5 or 6 inner wires. Different diameter and configuration
from maker to maker. Pictures of DIN connectors DIN Cable...
Distortion
A general term when the object is not shown exactly as
is.
DNS
1)Domain Name System. A general purpose distributed, replicated,
data query service. Its principal use is the lookup of
host IP addresses based on host names. 2)Domain Name Server.
A computer that converts host names, such as www.pelikancam.com
to its corresponding IP Address, such as 67.100.253.111
DRAM
Dynamic Random Access Memory. Most common RAM (Random
Access Memory) for PC.
DSL
Digital Subscriber Line. A technology for bringing higher-bandwidth
information to homes and businesses over ordinary copper
telephone lines.
DVR
Digital Video Recorder; records video pictures digitally.
Dwell Time
The length of time a switcher displays one camera before
sequencing to the next.
E
EIA
Electronic Industries Association. American standard for
B/W camera system.
ELC (Electronic Light Control)
Compensates for moderate light changes in indoor applications
without the use of auto iris lenses. Select this mode
when a fixed iris lens or manual iris lens is used.
Electronic Shutter
Compensates for moderate light changes in indoor
applications without the use of auto iris lenses.
EMI
Electro-Magnetic Interference.
Ethernet
The most widely installed Local Area Network (LAN) technology.
Specified in a standard IEEE802.3.10/100 BASE-T, the most
commonly installed Ethernet system, provides transmission
speed up to 100 megabits per second.
Extranet
A private network. It uses the Internet Protocol to securely
share part of a business information with suppliers, vendors
or others.
F
FCC
Federal Communications Commission; controls also wireless
camera system as one of the commercial broadcasting systems.
FFL
Fixed Focal Length Lens
Fiber-Optic Cable
One of the video transmission ways, being used for a long
distance transmission up to miles.
Field
One video frame is composed of two fields; one field consists
of the odd numbered lines in the frame and the other field
consists of the even numbered lines.
Field Frequency
The number of fields per second.
Field Of View
FOV. The width, height or diameter of a scene to be monitored.
Usually determined by the focal length of a lens, the
sensor format and the distance to the objects.
Firewall
A set of programs that protects the resources of a private
network from outside users.
FL
Focal Length. The distance from the center of a lens (or,
the secondary principal point, if it has) to the focal
point (sensor). The longer the focal length, the narrower
is the angle of view.
Flange-back Adjusting Ring
Some models of CCTV cameras have built-in Flange-back
Adjusting Ring, which adjusts the back-focal distance
or picture focus. A C-Ring (5mm spacer ring) is not required
when a C-Mount lens is to be mounted to a camera that
has built-in Flange-back Adjusting Ring.
Flash Memory
Or flash RAM (Random Access Memory). A type of constantly
powered nonvolatile memory that can be erased and reprogrammed
in units of memory called blocks.
f-number (f-stop)
Optical or lens speed. Smaller f-number means faster lens.
Focal Length
FL. The distance from the center of a lens (or, the secondary
principal point, if it has) to the focal point (sensor).
The longer the focal length, the narrower is the angle
of view.
FOV
Field of View. The width, height or diameter of a scene
to be monitored. Usually determined by the focal length
of a lens, the sensor format and the distance to the objects.
Frame
A whole video image; is composed of two interlaced fields.
A CCD chip produces 30 frames per second at NTSC system
and 25 frames at PAL.
Frame Frequency
The number of frames per second. The frame frequency is
half the field frequency.
FTP
File Transfer Protocol. A way to exchange files between
computers on the Internet
G
Gamma
Degree of contrast in a video picture between output magnitude
and input magnitude. GB
Gigabyte.
Genlock
A device that adjusts the frequency of internal sync to
an external data.
Ghost
A shadowy or weak image in the received picture, offset
to either the right or to the left of the primary image.
H
HTML
Hyper Text Markup Language. A set of codes inserted
in a file intended for display on a World Wide Web browser
page.
HUB
As a network product, a hub may include a group of modem
cards for dial-in users, a gateway card for connections
to a Local Area Network (LAN), and a connection to a line.
Hz (Hertz)
Cycles per second.
I
ICMP
Internet Control Message Protocol. A message control and
error-reporting protocol.
Impedance
Electrical characteristic of a system or component, expressed
in ohms. CCTV industry has standardized 75-ohm impedance.
Infrared (IR) Light
Invisible light beyond the 750 nanometers(red end of the
visible lights).
INT
Internal sync mode that sets to internal 2:1 interlace.
Intranet
A private network. It may consist of many LAN and/or WAN.
IP
Internet Protocol. A set of rules to send and receive
messages at the Internet address level.
Iris
An adjustable opto-mechanical aperture built into a camera
that controls the amount of lights coming through the
lens.
ISDN
Integrated Service Digital Network. A set of standard
for digital transmission over ordinary telephone copper
wire.
J
JPEG
Joint Photographic Experts Group. A graphic image file or
a image compression algorithm.
K
KB
Kilobyte
Kbps
Kilobits per second. A measure of bandwidth.
L
LAN
Local Area Network. A group of computers and associated
devices that share a common communications line.
LED
Light Emitting Diode.
Lens Mount
The area where a lens is mounted. There are two types;
C- or CS-Mount.
Lens Speed
Optical speed, expressed by f-number. Smaller f-number
means faster lens.
Linux
An UNIX-like operating system. Very efficient and fast-performing
system.
LL
Line Lock mode
LNB (Low Noise Block Converter)
The part of satellite dish that hangs off of the arm and
looks like a flashlight. It is what captures the digital
signal from the satellite.
Lux
Lumens per Square Meter; unit of illumination amount.
M
MATV
Multiple Access Television. The method of distributing
TV signals by broadcasting them through the air.
MB
Megabyte
Mbps
Megabits per second. A measure of bandwidth.
Mini-DIN
Multi-wire cable with Mini-DIN connectors at both ends.
Usually has 4 inner wires. Pictures of
Mini-DIN connectors
Monochrome Signal
Black and White signal.
MOD (Minimum Object Distance)
The closest distance a lens will be able to focus upon
an object. Wider angle (shorter focal length) lenses generally
have a smaller MOD than larger focal length (narrower
angle) lenses.
MOS
Metal-oxide Semiconductor. One of video image chips like
CCD, but it produces lower quality video.
Motorized Lens
A camera lens equipped with small electric motor that
enables focusing lens, opening or closing the iris diaphragm,
or changing the focal length.
MPEG
Moving Picture Experts Group. A standard for a digital
video & audio compression.
Multiplexer (MUX)
Combines two or more video/audio signals into one channel.
Usually accepts 10 or 16 video inputs and displays them
in various formats.
N
Network
A series of points or connection points interconnected
by communication paths.
Noise
Undesired signals that corrupt the original video signals
and may reduce he image quality.
NTSC
National Television System Committee; formulates standards
for American color television system. NTSC system has
525 horizontal scan lines and 30 frames per second.
O
Optical Speed
Lens speed, expressed by f-number. Smaller f-number means
faster lens.
Optical Axis
Optical centerline that passes through the center of a
lens or mirror, etc.
P
PAL
Phase Alternating Line system. A color television system
used in Europe, Australia, parts of Africa and the Middle
East. It has 625 horizontal scan lines and 25 frames per
second.
Pan and Tilt
A Camera mounting device that allows movement in both
side ways and up or down.
Pan
Rotating or scanning a camera side ways to view an area
in a horizontal direction.
Peak-To-Peak
The amplitude difference between the most positive and
the most negative excursions of a signal.
Picture Element (Pixel)
Photo sensor site in an image sensor like CCD chip; converts
the input light image to an electronic signal.
Pinhole Lens
A lens with a relatively small front opening so it can
be used in covert application.
Pixel
Picture Element. Photo sensor site in a image sensor like
CCD chip <http://www.cctvconsult.com/pages/ccd.htm>
; converts the input light image to an electronic signal.
PPP
Point-to-Point Protocol. For communications between two
computers using a serial interface.
PPPoE
Point-to-Point Protocol over Ethernet.
Presets
The pre-positioning of pan, tilt and zoom cameras by the
use of potentiometers in the moving parts of the camera
head. These allow the control equipment to store and move
to a set reference point when the controller dictates
or when an alarm exists.
Protocol
A special set of rules (in information technology).
PSTN
Public Switched Telephone Network.
Q
Quad Splitter
Combines up to 4 video inputs into one channel and displays
them on one monitor screen split into 4.
R
RAM
Random Access Memory. The place in a computer where the
operating system, application programs, and data in current
use are kept temporarily so that they can be quickly reached
by the computer's processor.
RARP
Reverse Address Resolution Protocol. For host machines
that don't know their IP address.
RCA
The Radio Corporation of America; conveniently used to
describe phono jack and plug, one of the audio/video connectors.
Resolution
Expressed by TV lines or pixels, it indicates the quality
level of video images.
RF
Radio Frequency.
RG59/U Cable
One of coaxial cables suitable for video transmission
in CCTV system.
Router
A device on the Internet that determines the next network
point to which a data should be forwarded.
RS-232 Port
A communication port with 15 pins.
S
SECAM
Sequential Couleur A'Memorie, a color television system
used in France, Russia and other countries that do not
use either the NTSC or PAL system. It has 625 horizontal
scan lines and 25 frames per second.
Sequential Switcher
Video Switcher. A device that allows the video signals
from multiple cameras to be displayed on a monitor, or
recorded on a VCR one at a time in sequence.
Server
A computer program that provides services to other computer
programs in the same or other computers. Or, the computer
that a server program runs.
Signal-to-Noise(S/N) Ratio
The ratio between the television signal and the noise;
expressed in decibel(dB). The higher the number the better.
SMTP
Simple Mail Transfer Protocol. TCP/IP used in sending
and receiving e-mail.
Switcher
Sequential Switcher or Video Switcher. A device that allows
the video signals from multiple cameras to be displayed
on a monitor, or recorded on a VCR one at a time in sequence.
SVHS (Super Video Home System)
Super VHS; a higher quality extension of the VHS home
videotape format.
S-Video
Transmits luminance and color portions separately, using
multiple wires, thus avoiding the color encoding process
and its inevitable loss of picture quality.
T
TCP
Transmission Control Protocol. A set of rules to exchange
messages with other Internet points at the information
packet level.
TCP/IP
Transmission Control Protocol / Internet Protocol. The
basic communication language or protocol of the Internet.
Time/Date Generator
Installed between a CCTV camera and a monitor, it generates
the information of Date, Time and camera ID.
Time Lapse VCR
A video recorder that can be set to record continuously
over long period of time. This can be anything from two
hours to 960 hours.
V
VHS
Victor Home System; used by most VCRs as the recording
medium.
Video Band
The frequency band used to transmit a composite video
signal.
Videocassette Recorder (VCR)
A device that accepts signals from a video camera/microphone
and records video/audio on magnetic tape in a cassette.
The VCR can play back recorded video/audio on a television
set or CCTV monitor.
Video Switcher
Switcher or Sequential Switcher. A device that allows
the video signals from multiple cameras to be displayed
on a monitor, or recorded on a VCR one at a time in sequence.
W
WAN
Wide Area Network.
Wavelet
A mathematical function useful in digital signal processing
and image compression. In the Internet communications,
wavelet has been used to compress images to a greater
extent than is generally possible with other methods such
as JPEG or MPEG.
Web Camera (or Web Camera Server)
A CCTV Camera with built-in web server computer.
Web Server
The computer program (housed in a computer) that serves
requested HTML pages or files.
Z
Zoom Lens
A lens of continuously variable focal length.
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