Outcome 1: data Communications

nullpitNetworking and Communications

Oct 23, 2013 (3 years and 11 months ago)

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Lesson 1


Point to Slide

Information and Communication Technology


Outcome 1:

Understand the main elements in a

data

C
ommunications

system.

Signaling


In telephony, signaling is the exchange of information between involved points in the network that
sets up, controls, and terminates each telephone call.




Signals


In electronics, a signal is an electric current used to convey data from one place to another. The
simplest form of signal is a direct current (DC) that is switched on and off; this is the

principle by
which the early telegraph worked. More complex signals consist of an alternating
-
current (AC) or
electromagnetic carrier that contains one or more data streams. Data is superimposed on a carrier
current or wave by means of a process called mo
dulation. Signal modulation can be done in either of
two main ways: analog and digital. In recent years, digital modulation has been getting more
common, while analog modulation methods have been used less and less. There are still plenty of
analog signals

around, however, and they will probably never become totally extinct. Except for DC
signals, all signal carriers have a definable frequency or frequencies. Signals also have a property
called wavelength, which is inversely proportional to the frequency.


Ex Of ADSL Layout


Medium


A medium is a third
-
party or element through which a message is communicated. In information
technology, a medium can be a physical transmission medium such as optical fiber.



Outcome 2:

Describe
hardware

and
software

used

i
n data communications

File Transfer


File transfer is the movement of one or more files from one location to another. A collection of
electronically
-
stored files can be moved by physically moving the electronic storage medium, such as
a computer diskette, hard disk, or compact disk from one p
lace to another or by sending the files
over a telecommunications medium. On the Internet, the File Transfer Protocol (FTP) is a common
way to transfer a single file or a relatively small number of files from one computer to another. For
larger file transf
ers (a single large file or a large collection of files), file compression and aggregation
into a single archive is commonly used. (E.g. A zip file) Electronic Data Interchange (EDI) is a popular
protocol for transferring files in a routine manner between

businesses.

From Wikipedia, the free encyclopedia

Electronic Data Interchange

(
EDI
) refers to the structured transmission of data between
organizations by electronic means. It is more than mere
E
-
mail
; for instance, organizations
might replace
bills of lading

and even
checks

with appropriate EDI messages. It also refers
specifically to a family of
standards
, including the
X12

series. However, EDI also exhibits its
pre
-
Internet roots, and the standards tend to focus on
ASCII
(American Standard Code for
Information Interchange)
-
formatted single messages rather than

the whole sequence of
conditions and exchanges that make up an inter
-
organization business process.



Outcome 3:

Describe
computer networks

and

specify interconnection devices.

Network


In information technology, a network is a series of points or node i
nterconnected by communication
paths. Networks can interconnect with other networks and can contain other networks. The most
common topology or general configurations of networks include the bus,
star
, and token ring
topologies. Networks can also be characterized in terms of spatial distance as local area networks
(LAN), metropolitan area networks (MAN), and wide area networks (WAN).

You can use Power Point


Network Topologies

ISO
-
OSI Layer Model


OS
I (Open Systems Interconnection) is a standard description or "reference model" for how
messages should be transmitted between any two points in a telecommunication network. Its
purpose is to guide product implementers so that their products will consisten
tly work with other
products. The reference model defines seven layers of functions that take place at each end of a
communication. Although OSI is not always strictly adhered to in terms of keeping related functions
together in a well
-
defined layer, many
if not most products involved in telecommunication make an
attempt to describe themselves in relation to the OSI model. It is also valuable as a single reference
view of communication that furnishes everyone a common ground for education and discussion.




Outcome 4:

Demonstrate an ability to
search, access

and retrieve remote information
.

&

Outcome 5:

Demonstrate an ability to
create info

t
hat can be accessed remotely.


Search Engines


On the Internet, a search engine is a coordinated set of programs
that includes

a spider (also called a "crawler" or a "bot") that goes to every page or representative pages on every
Web site that wants to be searchable and reads it, using hypertext links on each page to discover
and read a site's other pages,

a

program that creates a huge index (sometimes called a "catalog") from the pages that have been
read

a program that receives your search request, compares it to the entries in the index, and returns
results to you

an

alternative to using a search engine is to explore a structured directory of topics. Yahoo, which
also lets you use its search engine, is the most widely
-
used directory on the Web. A number of Web
portal sites offer both the search engine and directory ap
proaches to finding information.

Web Sites


A Web site is a collection of Web files on a particular subject that includes a beginning file called a
homepage. A synonym and less frequently used term for Web site is "Web presence." That term
seems to bette
r express the idea that a site is not tied to specific geographic location, but is
"somewhere in cyberspace." However, "Web site" seems to be used much more frequently. You can
have multiple Web sites that cross
-
link to files on each others' sites. This si
mply means that you've
identified two starting places or home pages for all the files.









Outcome 6:

Design an
appropriate ICT solution

to a given business context


LAN


A local area network (LAN) is a group of computers and associated devices that s
hare a common
communications line and typically share the resources of a single processor or server within a small
geographic area (for example, within an office building). Usually, the server has applications and
data storage that are shared in common by
multiple computer users. A local area network may serve
as few as two or three users (for example, in a home network) or many as thousands of users (for
example, in an FDDI network).

The main local area network technologies are Ethernet, token ring, Arcne
t and FDDI (Fiber
Distributed Data Interface) Typically, a suite of application programs can be kept on the LAN server.
Users who need an application frequently can download it once and then run it from their local hard
disk. Users can order printing and
other services as needed through applications run on the LAN
server. A user can share files with others at the LAN server; read and write access is maintained by a
LAN administrator.


Telecommunications


Digital


Digital describes electronic technology th
at generates, stores, and processes data in terms of two
states: positive and non
-
positive. Positive is expressed or represented by the number 1 and non
-
positive by the number 0. Thus, data transmitted or stored with digital technology is expressed as a
st
ring of 0's and 1's. Each of these state digits is referred to as a bit (and a string of bits that a
computer can address individually as a group is a byte).

Prior to digital technology, electronic transmission was limited to analog technology, which conv
eys
data as electronic signals of varying frequency or amplitude that are added to carrier waves of a
given frequency. Broadcast and phone transmission has conventionally used analog technology.

Digital technology is primarily used with new physical commu
nications media, such as satellite and
fiber optic transmission. A modem is used to convert the digital information in your computer to
analog signals for your phone line and to convert analog phone signals to digital information for your
computer.





Data Communications


Digital
-
to
-
analog conversion


Digital
-
to
-
analog conversion

is a process in which signals having a few (usually two) defined levels or
states (digital) are converted into signals having a theoretically infinite number of states (analog)
. A
common example is the processing, by a
modem, of

computer data into audio
-
frequency (AF) tones
that can be transmitted over a twisted pair telephone line. The circuit that performs this function is a
digital
-
to
-
analog converter (DAC).

Basically, digita
l
-
to
-
analog conversion is the opposite of analog
-
to
-
digital conversion. In most cases,
if an analog
-
to
-
digital converter (ADC) is placed in a communications circuit after a DAC, the digital
signal output is identical to the digital signal input. Also, in m
ost instances when a DAC is placed after
an ADC, the analog signal output is identical to the analog signal input.

Binary digital impulses, all by themselves, appear as long strings of ones and zeros, and have no
apparent meaning to a human observer. But w
hen a DAC is used to decode the binary digital signals,
meaningful output appears. This might be a voice, a picture, a musical tune, or mechanical motion.


Digital Networks



Information is mostly analogue, only a few can exist in digital form.



All
Information can be changed to digital form at a significant loss.



Digital Information can never be changed back to the original analogue form, only an
approximation of it!