Axis Q1755 Bedienungsanleitung PDF herunterladen (Seite 47)

AXIS Q1755 - Glossary of Terms

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

translate Internet domain 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

organ

izations who wish to centralize 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.

Ethernet - Ethernet is the most widely installed local area

netw

ork technology. An Ethernet LAN typically uses

special grades of twisted pair wires. The most commonly

installed Ethernet systems are 10BASE-T and

100BASE-T10, which provide transmission speeds up to 10

Mbps and 100 Mbps respectively.

ETRAX (Ethernet Token Ring AXIS) - Axis' own

micr

oprocessor.

Factory default settings - These are the settings that

origina

lly applied for a device when it was first delivered

from the factory. If it should become necessary to reset a

device to its factory default settings, this will, for many

devices, completely reset any settings that were changed

by the user.

Firewall - A firewall works as a barrier between networks,

e.g

. between a Local Area Network and the Internet. The

firewall ensures that only authorized users are allowed to

access the one network from the other. A firewall can be

software running on a computer, or it can be a standalone

hardware device.

Focal length - Measured in millimeters, the focal length of

a cam

era lens determines the width of the horizontal field

of view, which in turn is measured in degrees.

FTP (File Transfer Protocol) - An application protocol that

uses

the TCP/IP protocols. It is used to exchange files

between computers/devices on networks.

Frame - A frame is a complete video image. In the 2:1

interla

ced scanning format of the RS-170 and CCIR

formats, a frame is made up of two separate fields of 262.5

or 312.5 lines interlaced at 60 or 50 Hz to form a complete

frame, which appears at 30 or 25 Hz. In video cameras with

a progressive scan, each frame is scanned line-by-line and

not interlaced; most are also displayed at 30 and 25 Hz.

Frame rate - The frame rate used to describe the frequency

at which

a video stream is updated is measured in frames

per second (fps). A higher frame rate is advantageous when

there is movement in the video stream, as it maintains

image quality throughout.

Full-duplex - Transmission of data in two directions

simultaneo

usly. In an audio system this would describe e.g.

a telephone systems. Half-duplex also provides

bi-directional communication, but only in one direction at

a time, as in a walkie-talkie system. See also Simplex.

Gain - Gain is the amplification factor and the extent to

which an

analog amplifier boosts the strength of a signal.

Amplification factors are usually expressed in terms of

power. The decibel (dB) is the most common way of

quantifying the gain of an amplifier.

Gateway - A gateway is a point in a network that acts as

an entry point to another network. In

a corporate network

for example, a computer server acting as a gateway often

also acts as a proxy server and a firewall server. A gateway

is often associated with both a router, which knows where

to direct a given packet of data that arrives at the gateway,

and a switch, which furnishes the actual path in and out of

the gateway for a given packet.

GIF (Graphics Interchange Format) - GIF is one of the most

com

mon file formats used for images in web pages. There

are two versions of the format, 87a and 89a. Version 89a

supports animations, i.e. a short sequence of images within

a single GIF file. A GIF89a can also be specified for

interlaced presentation.

GOV (Group Of VOPs) - A group of VOPs is the basic unit

an H.264 video stream. The GOV contains different

types and numbers of VOPs (I-VOPs, P-VOPs) as

determined by the GOV length and GOV structure. See also

VOP.

GOV length - The GOV length determines the number of

imag

es (VOPs) in the GOV structure. See also GOV and

VOP.

GOV structure - The GOV structure describes the

com

position of an H.264 video stream, as regards the type

of images (I-VOPs or P-VOPs) included in the stream, and

their internal order. See also GOV and VOP.

H.264 - A standard for video compression, also known as

MPEG-4 Part 10.

Half-duplex - See Full-duplex.

HDTV - High-definition television, high resolution digital

vide

HTML (Hypertext Markup Language) - HTML is the set of

"mark

up" symbols or codes inserted in a file intended for

display in web browser. The markup tells the browser how

to display the page's words and images for the user.

HTTP (Hypertext Transfer Protocol) - HTTP is the set of

rules for e

xchanging files (text, graphic images, sound,

video, and other multimedia files) on the web. The HTTP

protocol runs on top of the TCP/IP suite of protocols.

Hub - A (network) hub is used to connect multiple devices

the network. The hub transmits all data to all devices

connected to it, whereas a switch will only transmit the

data to the device it is specifically intended for.

IEEE 802.11 - A family of standards for wireless LANs. The

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