Upload
saraahghori
View
223
Download
0
Embed Size (px)
Citation preview
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 1/27
The distance over which data moves within a
computer may vary from a few thousandths of
an inch, as is the case within a single IC chip,
to as much as several feet along the backplaneof the main circuit board. Over such small
distances, digital data may be transmitted as
direct, two-level electrical signals over simple
copper conductors. Except for the fastest
computers, circuit designers are not very
concerned about the shape of the conductor or the analog characteristics of signal
transmission.
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 2/27
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 3/27
�To allow computers with different disk
OS, languages, and cabling to share
resources.
�I would define data communication asthe transfer of information between two
points, either via an analogue (sine wave)
electrical signal. or digital (binary ) signal
via electrical pulses or optically via light
pulses�Data communication is transmission of
digital data through communication
systems . This has the objective of
sending any documents or books at
highest speeds and lowest cost.
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 4/27
Before the advent of computer networks that were based upon some type of telecommunications system, communication
between calculation machines and early computers was performed by human users by carrying instructions between them.
Many of the social behaviors seen in today's Internet were demonstrably present in the nineteenth century and arguably in
even earlier networks using visual signals.
�In September 1940 George Stibitz used a teletype machine to send instructions for a problem set from his Model at
Dartmouth College to his Complex Number Calculator in New York and received results back by the same means.
Linking output systems like teletypes to computers was an interest at the Advanced Research Projects Agency (ARPA)
when, in 1962, J.C.R. Licklider was hired and developed a working group he called the "Intergalactic Network", a
precursor to the ARPANET.
�In 1964, researchers at Dartmouth developed the Dartmouth Time Sharing System for distributed users of large computer
systems. The same year, at Massachusetts Institute of Technology, a research group supported by General Electric and
Bell Labs used a computer to route and manage telephone connections.
�Throughout the 1960s Leonard Kleinrock , Paul Baran and Donald Davies independently conceptualized and developed
network systems which used packets that could be used in a network between computer systems.
�1965 Thomas Merrill and Lawrence G. Roberts created the first wide area network (WAN).
�The first widely used telephone switch that used true computer control was introduced by Western Electric in 1965.
�In 1969 the University of California at Los Angeles, the Stanford Research Institute, University of California at Santa
Barbara, and the University of Utah were connected as the beginning of the ARPANET network using 50 kbit/s circuits.
�Commercial services using X.25 were deployed in 1972, and later used as an underlying infrastructure for expanding
TCP/IP networks.
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 5/27
Data Flow Diagram Symbols:
There are some symbols that are used in the drawing of business process diagrams (data flow diagrams). These
are now explained, together with the rules that apply to
them.
Flow diagrams in general are usually designed using
simple symbols such as a rectangle, an oval or a circle
depicting a processes, data stored or an external entity,
and arrows are generally used to depict the data flow
from one step to another.
ADFD usually comprises of four components. These
four components can be represented by four simple
symbols. These symbols can be explained in detail as
follows: External entities (source/destination of data) are
represented by squares; Processes (input-processing-
output) are represented by rectangles with rounded
corners; Data Flows (physical or electronic data) are
represented by arrows; and finally, Data Stores (physical
or electronic like XML files) are represented by open-
ended rectangles.
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 6/27
Data flow diagrams present the logical
flow of information through a system in
graphical or pictorial form. Data flow
diagrams have only four symbols, which
makes useful for communication between
analysts and users. Data flow diagrams
(DFDs) show the data used and provided
by processes within a system. DFDs make
use of four basic symbols.Create structured analysis, information
flow, process-oriented, data-oriented, and
data process diagrams as well as data
flowcharts.
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 7/27
A communications channel is a pathway over which information can
be conveyed. It may be defined by a physical wire that connectscommunicating devices, or by a radio, laser, or other radiated energy
source that has no obvious physical presence. Information sent
through a communications channel has a source from which the
information originates, and a destination to which the information is
delivered. Although information originates from a single source, there
may be more than one destination, depending upon how many receivestations are linked to the channel and how much energy the
transmitted signal possesses.
In a digital communications channel, the information is represented
by individual data bits, which may be encapsulated into multibit
message units. A byte, which consists of eight bits, is an example of amessage unit that may be conveyed through a digital communications
channel. A collection of bytes may itself be grouped into a frame or
other higher-level message unit. Such multiple levels of encapsulation
facilitate the handling of messages in a complex data communications
network
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 8/27
INTERNET:
The Internet is a global system of interconnected
computer networks that use the standard Internet Protocol
Suite (TCP/IP) to serve billions of users worldwide. It is a
network of networks that consists of millions of private,
public, academic, business, and government networks, of
local to global scope, that are linked by a broad array of
electronic, wireless and optical networking technologies.
The Internet carries a vast range of information resourcesand services, such as the inter-linked hypertext documents
of the World Wide Web (WWW) and the infrastructure to
support electronic mail.
Most traditional communications media including
telephone, music, film, and television are reshaped or
redefined by the Internet, giving birth to new services such
as Voice over Internet Protocol (VoIP) and IPTV.
Newspaper, book and other print publishing are adaptingto Web site technology, or are reshaped into blogging and
web feeds. The Internet has enabled or accelerated new
forms of human interactions through instant messaging,
Internet forums, and social networking. Online shopping
has boomed both for major retail outlets and small artisans
and traders. Business-to-business and financial services on
the Internet affect supply chains across entire industries
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 9/27
WIRELESSIn telecommunications, wireless communication may
be used to transfer information over short distances (a
few meters as in television remote control) or long
distances (thousands or millions of kilometers for radio
communications). The term is often shortened to
"wireless". It encompasses various types of fixed,
mobile, and portable two-way radios, cellular
telephones, personal digital assistants (PDAs), and
wireless networking. Other examples of wireless
technology include GPS units, garage door openers and
or garage doors, wireless computer mice, keyboards
and headsets, satellite television and cordless
telephones
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 10/27
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 11/27
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 12/27
The interactive Communication And Distance Education (CADE) system operates in a live satellite, teleconferencing, or
streaming video broadcast environment. CADE facilitates one-way video, two-way audio and data communication. It can be
used for such diverse interactive applications as:
y Distance Learning & Training
y Corporate Communication
y New product/process introduction
y Internal marketing surveys with immediate results
Meetings that don¶t require expensive and time-consuming travel
Improving the ³touch´ with remote locationsVendor sponsored presentationsInviting customers to local sites for special presentationsExtracting hidden "knowledge assets" andFacilitating knowledge transferCADE provides live data, text, web, and audio interaction between the Instructor and or Presenterand the remote participants located throughout the country or the world.Audio - Participant's can speak over an internet connectionData - Collect answers to multiple-choice, true/false, yes/no, numeric questionsRecorded Audio - Record audio questions for topic expertsText - Live chat between Presenter and a site or groups of sitesVideo - View streaming video in lieu of satellite broadcastWeb Pages - Synchronized delivery of web pages to learnersThe CADE system also supports off-Line applications. Not everything happens during a livebroadcast so the CADE
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 13/27
Yes, there are vast differences. But the biggest difference by far
is that there is less face-to-face communication. It's either
(cell)phone, E-mail or Festoon. No matter which alternative,
face-to-face communication has an extra dimension: facial
expression.
When I am on the phone I like to imagine what the other party
really thinks. I can listen to his tone of voice, try to understand
the pauses and try to figure out what he/she is really saying.
That is why counseling over the internet is only second best
In the past there was communication devices that we now do
not have. In the past there were such things as smoke signals,
telegraphs, carrier pigeons, animal sounds and early
telephones. plus letters. In the present we have cell phones,
telephones, email addresses, fax machines, and more. so that's
the differences of the communication system in the past and
today the presents of the 21st centuries.Today the internet is more high powered and is used alot for
doing research and finding information.In the past the internet
wasn't able to do alot of these things
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 14/27
Near Field Communication (NFC) does seem to be one of the more interesting trends for this year,
where it will see action on the mobile platform soon as well. NFC is also making its way into the US
and Europe markets via a range of channels, and you can add BMW to the list of supporters with its
NFC key of the future. BMW researchers are hoping to link the vehicle¶s key to its navigation and
entertainment system, letting you for example, reserve a hotel room for your anniversary or
purchase coach tickets right from the comfort of your ultimate driving machine. Currently however,all of this remains in the R&D phase and will most likely see implementation in the next generation of
ConnectedDrive if all goes well.
³Welcome to the worlds most influential media forum´, said HSH Prince Albert II of Monaco at the
beginning of the Monaco Media Forum 2010. Indeed the event is not only inspirational, but is also
bringing together the a very influential group of people in the media business. During the almost
three days, I met founders, entrepreneurs, investors but also executives of the big media
companies. Here are some key trends reflected in my video interviews«.
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 15/27
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 16/27
Current trends in technical communications
The rise of embedded user assistance
Many technical writers are developing usability skills and
leveraging them to help improve the product interface. Help
is being delivered within the interface itself. Drop-down lists
of topics related to an interface component, hint text below
a GUI field, and other such embedded user assistance
models allow users to get help without leaving the
application interface.Traditional help lives as a separate application, and
requires users to learn to navigate the help interface.
However, embedded help is less removed from the product
and is less disruptive to the overall workflow.
Currently there are few embedded user assistance tools
available, but I believe this will be a promising area of
growth for tool developers in the near future.
Developer cooperation is also a potential stumbling block
since most writers have no control over the productinterface. Technical communicators need to build positive
relationships with developers and show them the benefits
of implementing embedded help.
Increased reliance on multimedia
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 17/27
T he Future of Wireless Data Communication:
The wireless data communication (WDC) services are penetrating the market increasingly faster in
recent years. The two main alternative WDC technologies are the wireless LAN and the mobile Internetservice. There is our previous research[1] about the services. These services show many differences in
their quality attributes, such as the device, quality of communication, data transmission speed, pricing
system and so on. Consumers¶ choice between these two alternatives will be determined by their
preferences over different quality attributes and in turn, will have a powerful impact on the evolution of
WDC services and related technologies in the future.
In this study, we analyze consumers¶ valuation of quality attributes in the wireless LAN and mobile
Internet services. Consumer choice is crucial to the success in the WDC-related businesses since the
WDC market is growing very fast and competition among the WDC service providers will become quite
intensive. Methodologically we employ conjoint analysis, which makes the respondents rate hypotheticalservice alternatives featuring various combinations of quality attributes. By estimating consumers¶
willingness to pay for the attributes of the WDC services based upon surveyed stated preference data
from the conjoint experiment, we predict the evolution of the WDC services and related technologies
along various quality dimensions compared with the result of previous research[1] using redesigned
questionnaire. Based on the estimation results, we draw policy implications for the national- and
company-level R&D strategy.
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 18/27
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 19/27
Data Communication Applications
Agenda
Application CategoryEvolutionApplicationsInternet, Intranet, & ExtranetConsiderationsApplication Category
Human-machine interactionPerson-to-personPerson-to-machine or machine-to-personMachine-to-machine
Type of informationVoice or dataStructured or unstructuredStatic image or dynamic image
TimelinessOn-lineReal-time
Store-and forwardBatch
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 20/27
EvolutionTelegraphAdministrative message switchingComputers
TelegraphMorse CodeDots and dashesSlow
No error correctionMessage Switching SystemsEquipment: teletypewriters
Types: torn tape message systemPoint-to-pointMultipoint lineCollision, polling, address, and protocolControl or master station and subordinate or slave
stationComputers
BenefitsInquiryFile updating
TimesharingOther applications (TPS, MIS, DSS, EX, EC)
TypesCentralizedDistributedClient-server
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 21/27
Applications - IAirline reservation system
American airline: Sabre systemUnited airline: Apollo reservationsystem
Automatic teller machineSwift: Society for WorldwideInterbank FinancialTelecommunication
Sales order entryPoint of saleUniversal product code
Applications - IIUnstructured data application
Electronic mail
Ownership of contentSimple mail transfer protocol(SMTP)
No foreign charactersNo executable filesLimited size
Multipurpose Internet mailextensions MIME
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 22/27
Applications - IIIImage application
Facsimile (FAX)
Simple for printed documentationTelevision
Purpose
SecurityInformationConference
Types
Freeze-frame & full-motion
One-way & two-wayInternet, Intranet, ExtranetInternet
Browser program
Netscape¶s NavigatorMicrosoft¶s Internet ExplorerUniform Resource Locator (URL)
World Wide Web (WWW)Hypertext transfer protocol (http)Internet service provider (ISP): tier 1, tier 2, tier 3
Intranet
ExtranetConsideration
Response timeUser expectation
consistency
SecurityPlanning for failures
Do nothing
Manual systemBack up computer & linesHot standby system
Disaster Recovery
Mutual aid pactCommercial service: Comdisco Disaster Recovery Services
Planning & testing regularly
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 23/27
Pros of Electronic Communication
The benefits of electronic communication is that people across the world can share televised pictures, conversations,
graphics, circuits and interactive softwares. The interaction between people residing in different geographical locations
have increased and have become promiscuous. The conversations are more visual and textual. This is helpful mainly for
hearing impaired people. With electronic communication, the recipient receives the message within a few seconds of the
sender sending it. The recipient can read the message anytime, anywhere according to his convenience.
The speed of conversation has increased and this has resulted in faster processing of important matters related to
business, finance, trade, etc. For example, you can instantly access the information present in your computer. As there
are no restrictions about time and place, people can sit at home and do their of fice work if the required resources are
available.This work arrangement is termed as telecommuting. The communicated messages can be stored permanently
or temporarily on disks or tapes for years or can even be printed and stored in files. The process of learning has become
simple and efficient as the information can be archived and retrieved according to the requirement. Since the
communication does not take place via hard copies, money spent for paper, printing and postal deliveries is saved. After
the mail is delivered to the receiver, it is placed safely in the hard disk of the receiver's computer. After the receiver
retrieves the mail, it is his responsibility to keep it safely
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 24/27
Cons of Electronic Communication
The main issue with electronic communication is security. Your computer can be
hacked and affected with computer virus. This can have an adverse effect on
the computer system and the network. The volume of transmitted data is large
and the transmission is fast. Hence, it becomes difficult for employers and
managers to absorb, process and understand it and provide proper feedbacks
to their employees. The speed with which the messages are transmitted often
changes the structure of the messages, which at times can be misinterpreted.
Electronic data can be duplicated identically without any proof of duplication.
These messages can also be modified. At times, people can intentionally send
malicious programs like viruses, worms and Trojans through emails, which is
difficult to detect.
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 25/27
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 26/27
8/7/2019 Dcs Final Ppts
http://slidepdf.com/reader/full/dcs-final-ppts 27/27