Axis 0213-004 Datasheet download pdf (Page 24)

AXIS 292 - Glossary of Terms

Glossary of Terms

ActiveX - A standard that enables software components to interact with

one another in a networked environment, regardless of the language(s)

used to create them. Web browsers may come into contact with ActiveX

controls, ActiveX documents, and ActiveX scripts. ActiveX controls are

often downloaded and installed automatically as required.

AF (Autofocus) - A system by which the camera lens automatically

ocuses on a selected part of the subject.

Angle - The field of view, relative to a standard lens in a 35mm still

came

ra, expressed in degrees, e.g. 30°. For practical purposes, this is the

area that a lens can cover, where the angle of view is determined by the

focal length of the lens. A wide-angle lens has a short focal length and

covers a wider angle of view than standard or telephoto lenses, which

have longer focal lengths.

ARP (Address Resolution Protocol)

- This protocol is used to associate

an IP address to a hardware MAC address. A request is broadcast on the

local network to discover the MAC address for an IP address.

ARTPEC (Axis Real Time Picture Enco

der) - This chip is used for image

compression.

ASIC (Application Specific Integra

ted Circuit) - A circuit designed for a

specific application, as opposed to a general purpose circuit, such as a

microprocessor.

Aspect ratio - A ratio of width to height in images. A common aspect

ratio used

for television screens and computer monitors is 4:3.

High-definition television (HDTV) uses an aspect ratio of 9:16.

Autoiris (or DC-Iris) - This special type of iris is electrically controlled

by th

e camera, to automatically regulate the amount of light allowed to

enter.

AVI (Audio Video Interleave) - A video format that supports

simultaneous p

layback of audio and video.

Bitmap - A bitmap is a data file representing a rectangular grid of pixels.

It de

fines a display space and color for each pixel (or "bit") in the display

space. This type of image is known as a "raster graphic." GIFs and JPEGs

are examples of image file types that contain bitmaps.

Because a bitmap uses this fixed raster method, it cannot easily be

rescale

d without losing definition. Conversely, a vector graphic image

uses geometrical shapes to represent the image, and can thus be quickly

rescaled.

Bit rate - The bit rate (in kbit/s or Mbit/s) is often referred to as speed,

but ac

tually defines the number of bits/time unit and not distance/time

unit.

Bluetooth - Bluetooth is an open standard for wireless transmission of

voice

and data between mobile devices (PCs, handheld computers,

telephones and printers).

Bonjour - Also known as zero-configuration networking, Bonjour

enab

les devices to automatically discover each other on a network,

without having to enter IP addresses or configure DNS servers. Bonjour is

a trademark of Apple Computer, Inc.

BOOTP (Bootstrap Protocol) - A protocol that can automatically

configure a ne

twork device (give it an IP address). BOOTP is the basis for

the Dynamic Host Configuration Protocol (DHCP).

Broadband - In network engineering terms, this describes transmission

methods where two or more signals s

hare the same carrier. In more

popular terminology, broadband is taken to mean high-speed data

transmission.

CCD (Charged Coupled Device) - This light-sensitive image device used

many digital cameras is a large integrated circuit that contains

hundreds of thousands of photo-sites (pixels) that convert light energy

into electronic signals. Its size is measured diagonally and can be 1/4",

1/3", 1/2" or 2/3".

CGI (Common Gateway Interface) - A specification for communication

betw

een a web server and other (CGI) programs. For example, a HTML

page that contains a form might use a CGI program to process the form

data once it is submitted.

CIF (Common Intermediate Format) - CIF refers to the analog video

resolutions

352x288 pixels (PAL) and 352x240 pixels (NTSC). See also

Resolution.

Client/Server - Client/server describes the relationship between two

mputer programs in which one program, the client, makes a service

request from another program, the server, which fulfils the request.

Typically, multiple client programs share the services of a common server

program. A web browser is a client program that requests services (the

sending of web pages or files) from a web server.

CMOS (Complementary Metal Oxide Semiconductor) - A CMOS is a

wid

ely used type of semiconductor that uses both negative and positive

circuits. Since only one of the circuit types is on at any given time, CMOS

chips require less power than chips using just one type of transistor.

CMOS image sensors also allow processing circuits to be included on the

same chip, an advantage not possible with CCD sensors, which are also

much more expensive to produce.

Coaxial cable - Coaxial cable is the standard means of transmitting

ana

log video in a CCTV system. Coaxial is also used by cable companies

to distribute television in residential buildings.

Codec - In communications engineering, a codec is usually a

der/decoder. Codecs are used in integrated circuits or chips that convert

e.g. analog video and audio signals into a digital format for transmission.

The codec also converts received digital signals back into analog format.

A codec uses analog-to-digital conversion and digital-to-analog

conversion in the same chip.

Codec can also mean compression/decomp

ression, in which case it is

generally taken to mean an algorithm or computer program for reducing

the size of large files and programs.

Composite video - A type of video signal in which the red, blue and

gree

n signals (sometimes audio signals too) are mixed together.

Compression - See Im

age Compression.

Contrast - Defines the degree of difference between the lightest and

darkest parts of an image

or video stream.

Control unit - If a CCTV system has more than one camera, there must be

a way

to control each video signal going to the VCR and the monitor.

There are three basic types of Video Control Unit; Multiplexer, Switch and

Quad.

DC-Iris - This special type of iris is electrically c

ontrolled by the camera,

to automatically regulate the amount of light allowed to enter.

Decoder - See vi

deo decoder.

De-interlacing - See in

terlacing.

DHCP (Dynamic Host Configuration Protocol) - DHCP is a protocol that

lets netw

ork administrators automate and centrally manage the

assignment of Internet Protocol (IP) addresses to network devices in a

network.

DHCP uses the concept of a "lease" or amount of time that a given IP

add

ress will be valid for a computer. The lease time can vary, depending

on how long a user is likely to require the network connection at a

particular location.

DHCP also supports static addresses for e.g. computers running web

serve

rs, which need a permanent IP address.

DNS (Domain Name System) - DNS is used to locate and translate

Internet doma

in names into IP (Internet Protocol) addresses. A domain

name is a meaningful and easy-to-remember name for an Internet

address. For example the domain name www.example.com is much easier

to remember than 192.0.34.166. The translation tables for domain names

are contained in Domain name servers.

Domain Server - Domains can also be used by organizations who wish

to cen

tralize the management of their (Windows) computers. Each user

within a domain has an account that usually allows them to log in to and

use any computer in the domain, although restrictions may also apply.

The domain server is the server that authenticates the users on the

network.

Duplex - See full-duplex.

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Axis 0213-004 Datasheet Page 24

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