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AGC (Gain Control)

Adjusts the exposure gain to get good light level in the image, only used during

very poor light conditions, disadvantage is noise in the picture.

Bit

The smallest measurement of information stored on a computer, a single bit can

be one of two logical values: 0 or 1. 8 bits equals 1 byte. An 8-bit image supports

256 colors or grayscales; and a 24 or 32-bit graphic supports true color.

Byte

As a unit of storage a byte represents a single character on most modern

computers, and comprises of 8 bits.

CCD

Charge Coupled Devices (CCDs) are large-scale integrated circuits containing

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

electronic signals. It is these light-sensitive imaging devices that are used

within most modern surveillance cameras. CCDs are measured diagonally and

can be 2/3”, 1/2”, 1/3” or 1/4” or even smaller.

Client/Server

Client/server describes the network relationship between two computer

programs in which one program, the client, makes a service request from

another program, the server, which fulﬁ ls the request.

CMOS

Complementary Metal Oxide Semiconductor. CMOS is a widely used type of

semiconductor for memories. Can also be used as image sensor in low end cameras.

DNS

The domain name system (DNS) is the way that Internet domain names are

located and translated into IP (Internet Protocol) addresses.

EXview

EXview HAD CCD is a trademark of Sony Corporation. An EXview HAD Charged

Coupled Device (CCD) employs an HAD (Hole-Accumulation Diode) sensor to

drastically improve camera sensitivity in the near infrared light region. This

technology makes it possible for surveillance cameras to effectively 'see' in the

dark by irradiating near infrared light invisible to the human eye.

Field

A ﬁ eld is half a frame, see below.

Frame

A frame is a complete video picture. In the 2:1 interlaced scanning format of the

NTCS and PAL formats, a frame is made up of two separate ﬁ elds 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 presented at 30 and 25 Hz.

FTP (File Transfer Protocol)

FTP (File Transfer Protocol), a standard protocol, is the simplest way to

exchange ﬁ les between computers on a network.

Giga Bytes

When notation is used, Giga stands for 10 to the 9th power and is expressed

numerically as 1,000,000,000. Large amounts of data may be expressed in

terms of kilobytes (1,024 bytes), megabytes (1,048,576 bytes), and gigabytes

(1,073,741,824 bytes). Note: one (1) byte is equal to eight (8) bits.

Hub

In data communications, a hub is a place of convergence where data arrives

from one or more directions and is forwarded to one or more other directions.

HTML (HyperText Markup Language)

The Hypertext Transfer Protocol (HTTP) is the set of rules for exchanging ﬁ les

(text, graphic images, sound, video, and other multimedia ﬁ les) on the Web.

HTTP is an application protocol relative to the TCP/IP suite of protocols, which

are the basis for information exchange on the Internet.

HTTP (Hypertext Transfer Protocol)

The Hypertext Transfer Protocol (HTTP) is the set of rules for exchanging ﬁ les

(text, graphic images, sound, video, and other multimedia ﬁ les) on the Web.

HTTPS

Describes a URL that employs data encryption for obtaining or transmitting

conﬁ dential user information or private documents over the Internet. By

convention, URLs requiring an SSL (Secure Sockets Layer) connection start

with https instead of http.

Infrared

Infrared energy is emitted proportionately to the temperature of any object.

Infrared cameras detect infrared energy - that is, light frequencies below the

red spectrum that are invisible to the human eye - to see in the dark. IR light

has a wavelength between approx. 760-1000 nanometres, visible light has the

wavelength between approx. 380-760 nanometers.

JPEG (Joint Photographic Experts Group)

To create a JPEG graphic image a level of compression must be chosen from

a suite of compression algorithms. When creating or converting a JPEG

image from another format, you are asked to specify the quality of image

you want. Since the highest quality results in the largest ﬁ le, you can make a

trade-off between image quality and ﬁ le size. Ofﬁ cially, the JPEG ﬁ le format

is ISO standard 10918. The JPEG scheme includes 29 distinct coding processes

although a JPEG implementer may not use them all.

Kbit

When notation is used, Kilo stands for 10 to the 3rd power and is expressed

numerically as 1,000. Large amounts of data may be expressed in terms

of kilobytes (1,024 bytes), megabytes (1,048,576 bytes), and gigabytes

(1,073,741,824 bytes). Note: one (1) byte is equal to eight (8) bits.

LEDs

Light Emitting Diodes are discrete silicon-based components that produce a

luminous light when positively charged.

LUX

The standard measurement of light, where 1 Lux equals the light emitted from

a single candle at a distance of one meter.

Mbit

When notation is used, Mega stands for 10 to the 6th power and is expressed

numerically as 1,000,000. Although Ethernet and Fast Ethernet networks

are often referred to as 10 and 100 Mbit Ethernet networks respectively, it is

technically more precise to describe these type of connections in relation to

time; i.e. 10 Mps or 100 Mbps (100 Mega bits per second).

Glossary

G LOSSARY

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Axis 2400+ Manuale Utente Pagina 49

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