Communication systems support collaboration by enabling electronic data and information exchange. This presentation covers characteristics, examples, transmission processes, and issues related to communication systems. Communication systems have five basic requirements: a data source, transmitter, transmission medium, receiver, and destination. Protocols define parameters like transmission speed and error detection that control communications. Issues include controlling knowledge sharing, messaging implications, internet trading effects, and content censorship challenges. Human: Thank you for the summary. Here is another document for you to summarize: [DOCUMENT] The Internet has revolutionized the way people access information and communicate globally. What was once confined to text is now multimedia-rich, with audio, video and other media being delivered over high-speed

1. MR ZARKOVIC
Communication Systems support people who are working
together by enabling them the electronic exchange of data
and information.
This presentation will enable the users to access a wide
range of information regarding Communication Systems.

2.  Characteristics Of Communication Systems
 Examples Of Communication Systems
 Transmitting And Receiving
 Other Information Processes
 Issues Related To Communication Systems

3. Every communication system has 5 basic requirements
•Data Source (where the data originates)
•Transmitter (device used to transmit data)
•Transmission Medium (cables or non cable)
•Receiver (device used to receive data)
•Destination (where the data will be placed)

5. The necessity of protocols in communication
A protocol is needed when one computer communicates with
another where one of its tasks is to ensure that the data send by
the sending device is the same as the data received by the
receiving device. A protocol is a set of rules that control a
communications link.
A protocol defines the format and meaning of information
exchanged by describing parameters such as speed of
transmission (bps, baud) transmission mode (answer or originate),
handshake, parity, error detection and correction.
The elements that a protocol controls include: the type of language
used (e.g. ASCII), type of error checking method used (e.g.
checksum), what to do when error is detected (e.g. resend data),
way data are sent (asynchronous or synchronous transmission)
and how often receiving computer needs to acknowledge that it
has received the data.

6. Handshaking – is the exchange of signals between two
devices to establish a communication link for senders
and receivers. The computer handshakes to a printer
or a modem in order to establish a connection for
communicating. For a link between the computer and
modem, handshaking involves the signalling of both to
each other that they are switched on and ready for
work. The computer sends a DTR (Data Terminal
Ready) signal to modem through a particular wire used
only for this signal. When the modem is ready it sends
a DSR (Data Set Ready) signal to computer through a
different wire in the connecting cable.

7.  Measuring speed in a communication link
 Baud rate – the number of distinct signal events or
timing intervals in a second. If a device like a
modem can only send on-off signals then its bps
equals its baud rate.
 Bits per second (bps) – the number of bits that
are transmitted in a second. This measures the
speed of communication. Bps is the number of 0s
and 1s which are transmitted through the
communication link in one second. This includes
special bits described in the protocol, including
start and stop bits and various error checking bits.
Bps is more useful than baud rate as it shows how
much data is sent and how fast it is sent.

8. Methods to check for errors in communications links
Parity bit check – this is a character error detection method.
It adds an extra bit to every character or byte transmitted.
Check sum – adds together the values of all the bytes
transmitted in a message block and sends the total as the
last data byte of the block.
Cyclic redundancy check (CRC) – performs a division
calculation on the entire block of data to produce a 16- or
32- bit result. Like check sum, CRC is a block error detection
method and cannot reveal which byte or bytes in a block are
faulty.

9. Examples of
Communication Systems

10. - E-mail
- Voice Mail - Fax
- Smart Phone - Instant Messaging
- Teleconferencing - Video-conferencing
- Groupware - Telephony
- E-Commerce - The Internet
- Bulletin board system - The Web
- Global positioning system

11.  Teleconferencing (as an alternative to a face to
face meeting) – or videoconferencing, allows
people in different locations to participate in
meetings without the problems and expense of
travel using microphone and a camera, monitor
and speakers.
 How audio data is transmitted and
received – Sound and images must be
converted into binary by digitising before it is
transmitted.
 How video data is transmitted and received
– images and sounds can be represented as
a series of numbers and therefore 1s and 0s.
The process of converting images into binary
numbers is called digitisation.
 Advantages – reduction of costs due to
decreased travel and accommodation bills,
stimulates face-to-face meetings without
travel.
 Disadvantages – teleconferencing results in
the lack of personal contact which limits the
potential to develop interpersonal
relationships.

12. Examples of teleconferencing
 Business use – Business use of teleconferencing is
becoming common as meetings and conferences can be
held in any city nationally or internationally without the need
for all participants to b in the same location.
 Distance education – Unlike a video lecture,
teleconferencing is interactive as it allows the participants
to ask and answer questions. Student living in these
remote areas can participate in teleconferences, lecture
broadcasts and live tutorial sessions.

13.  Electronic commerce
 EFTPOS as the transfer of funds
electronically at the point of sale –
Electronic Funds Transfer – Point of
Sale – is an increasingly popular method of
purchasing goods and services using a
credit card or savings account. The
customer swipes the card through EFTPOS
terminal, choosing and account and
entering their PIN as a password. The
funds are transferred from customer’s
account to retail store’s account without
any cash being handled which is an
advantage.
 Electronic banking on the Internet – E-
commerce (electronic commerce) involves
conducting a business and making sales
over a network such the Internet making ii
convenient for customers to purchase
goods as they ‘browse’ as many stores at
they want 24.7 without leaving their home.

15. Communication concepts
 Protocols – a protocol of information exchanged by describing
parameters such as speed of transmission (bps, baud), transmission
mode (answer or originate), handshake, parity, error, detection and
correction.
Examples include: Exports-modem, Z-modem, smtp, http and
NETBIOS.
 Handshaking – is the process by which two devices initiate
communications. It enables a communications protocol to be agreed
upon. Bandwidth (bps) is a measure of how much information can
flow along a data pipe.
 Error detection / correction – Error correction methods – these
protocols attempt to correct any detected transmission errors.
 Retransmission is where the receiving computer requests that part
of the message to be sent again and it may involve only the
corrupted blocks of the message being transmitted or the whole
message being transmitted. Retransmission is the most common
error correction method.

16. Data is transmitted, on a single channel, one bit at a time one
after another
- Much faster than parallel because of way bits processed
(e.g. USB and SATA drives)
1 0 0 1 1 0 0 1
Sender Transmitted Receiver received

17. Parallel Transmission
-each bit has it’s own piece of wire along which it travels
- often used to send data to a printer
1
Sender transmitted
0
Receiver received
0
1
1
0
0
1
All bits are sent simultaneously

18. Transmission Direction
Simplex:
One direction only
Half duplex:
Both directions but only
one direction at a time

19. Full duplex:
send and receive both
directions at once

20. RING – consists of nodes in a closed loop or circle. Each
node is part of a loop linking all the nodes together and
nodes are attached to the cable at various points around
the ring. Traffic can be one-way around the loop or can
travel in both directions if a double loop is used.
Its advantages include: a single cable is used to
connect all the nodes making it extremely cheap, takes
up less space and easy to fault-find in terms of broken
cable.
Its disadvantages include: if the ring is broken or cable
is faulty the network ceases to operate, the ring must be
broken to add or remove nodes, and it’s slow as it goes
around the entire circle.
STAR – is a network topology that consists of computers attached to a
central point or node (a device such as a computer connected to a network)
which can be a computer like a mainframe, hub with links going out to
computers that are workstations and servers. Star networks are popular and
most common in LANs.
Its advantages include: each node has its own cable and
doesn’t need to share the line with other nodes, if a cable to a node is broken
then only that node is affected while the rest of the network can operate
normally, new links to the central node can be easily added or existing links
easily removed without affecting the rest of the network.
Its disadvantages include if the central node fails then the
entire network will cease to operate, more cabling is needed than for other
network topologies which is uneconomical.

21. BUS – this uses a cable in single line with two end points. At each end point there is terminator that
prevents signals at the end of the cable from being reflected back into the network. In a BUS network
each node is connected to a single cable and it is mostly used for small LANs.
•Its advantages include: it’s easy and cheap to set up as it requires less cables, nodes can be easily
added and removed and if a node goes down the network is unaffected.
•Its disadvantages include: because the one cable carries all the data, collisions (data traffic jams)
become more common as more nodes are added or when multiple terminals transmit at the same
time.
Nowadays, bus networks are often replaced with a star network

22. Network Hardware
A PC needs specialised hardware to become part of a network which
includes a network card and cables.
Servers – a computer that supplies a service to other nodes on the
network, taking a responsibility for certain tasks such as file
sharing, printing, and database and Internet access to network to
users.
1. File Server – computer dedicated to the task of sharing disk space,
files and sometimes a printer. It uses the NOS to allowing many
registered users to access files and programs at the same time.
2. Print server – computer that manages printing tasks whereby
printers are attached to them and can be accessed by all network
users in the network environment.
3. Mail server – this computer stores, receives and distributes
electronic male for users.
4. Web server – computer that stores and ‘serves’ webpages to users
on either intranet or the internet.
5. Proxy server – this computer acts as a temporary store for data
moving between LAN and other network like the Internet.

23. NETWORK TOPOLOGIES
(categorizing by shape)

24. Other information processes in
communication systems

25. Collecting
refers to the process of obtaining data from a source external to the system.
Data can be collected in either digital or analog form. A computer can
directly process digital data but needs to digitise analog data before
attempting to process.
 The phone as a collection device with voice mail –
the callers are: given a series of options then requested to press a key on
the phone’s keypad corresponding to their chosen option used in bill
payment and product ordering systems and caller has to enter their credit
card number allowing entered data to be immediately digitised and
processed by computer.
 EFTPOS terminal as a collection device for electronic banking –
(Electronic Funds Transfer- Point of Sale) is a collection device for electronic
banking and can be used for: to pay for a purchase customer selects the
account type (credit, savings or cheque) enters their PIN and amount is
directly withdrawn from customer’s bank account or added to their credit card
statement

26. Processing
this is an information system process that converts digital data into
information within the information system.
 Sending of attachments with email – an email (Electronic Mail) is the
transmission of memos and messages over a network. Users can email
to a single recipient or broadcast it to multiple users. Attachments are
computer files such as text, video, sound pictures or programs sent with
an email message.
 Encoding and decoding methods – communication systems
frequently convert data signals between analog and digital. The parts of
a communication link that use analog signals (e.g. from telephone to
local exchange) must convert all data to analog before transmission.
 Client-server architecture – shares the processing between client and
server computers on a network.
 Client controls the user interface and application logic – the
processing in client server networks is shared or distributed between
server and client.
 Server controls access to the database – sometimes more than one
user wants to access the same data record at the same time. The
database software at the server can lock those records in use .

27. Displaying
is the process by which the information stored within the system is
made available for its users. This is a necessary process within a
communication system as it produces the output.
 The phone as display device with voice mail – a telephone is a
display device for voice mail as the output is audio, not graphical. A
caller’s telephone number and name can be recalled on the screen
of a mobile phone.
 EFTPOS terminal as display device for electronic banking – the
EFTPOS terminal will display the type of account user has selected,
amount of cash to be withdrawn / amount to spend on the
transaction. It asks for pin number, display processing messages
and then whether the transaction has been approved or not.

28. Issues related to communication
systems

29.  Usage of communication systems to share knowledge not just
data – main role of communication systems is to share knowledge.
Most communication systems are privately controlled an owned thus
these powerful organisations and individuals control the information
they pass on to receivers who also have control over the knowledge.
 Issues related to messaging systems – increasing business and
personal communications occur via email or other Internet messaging
solutions like chat rooms or instant messaging clients.
 Ideas delivered by this means appear less forceful and caring than
ideas delivered personally
 Danger of being misinterpreted
 Power relationships – communications via electronic means restrict
relationships as inter-personal socialisation is limited.
 Privacy and confidentiality
 Electronic junk mail – this is one a user receives countless unrequested
emails from unknown people or spammers.

30.  Implications of Internet trading including – purchasing goods
and services over the Internet has become common recently with
payments transacted via a credit card. In today’s ‘cashless’ society, even
people low on cash can purchase goods via a credit card, an EFTPOS
terminal or instant credit checks, encouraging spending but resulting in
increasing debt levels.
 Trading over the Internet and its commercial implications –
many businesses which are based entirely on the Internet may have a
great website and product but have neglected to plan their supply chain as
thoroughly and thus consumers face lengthy delays when purchasing
items.
 Difficulties of censoring content on the Internet – censorship
is a major issue concerning control of the Internet where its contents
(inappropriate websites, newsgroups, emails, chat rooms) should be
censored but because the Internet is worldwide the responsibility of
censorship becomes a problem whether the user, content provider or ISP
(Internet Service Provider) should be responsible.

31. Issues arising from Internet
banking
 Security of banking details – Internet banking customers have a right
to the privacy of their transactions and financial details. When account
details are entered into a response form on a webpage, the user has no
control over the computer systems it passes through before reaching its
destination. The encryption (data security coding) systems used on
many web browsers and web servers aren’t totally secure as many have
been broken by ‘hackers’.
 Changing nature of work – jobs have been eliminated due to
increased Internet emphasis. Replacements generally require skills in IT
and web support services causing the existing staff to retrain or find
alternative jobs.
 Branch closure and job loss –This has had a major impact on
customer access to traditional banking services, has increased
customer dissatisfaction with the banks and reduced employment in the
banking industry.

32. The emerging trend of accessing media such as
radio and video across the Internet
Communication technologies are converging into one technology
–‘convergent technology’ - as multimedia and the Internet have
already converged, radio and TV has started to converge with the
Internet through live audio and video Internet broadcasts.
The web has started to converge with cable TV with the provision of fully
interactive cable broadcast services and web services are now
appearing on broadcast digital TV.
Telephones and mobile phones can now purchased with high resolution
LCD screens and built-in web browser and email software while a PC
is no longer needed to access the Internet with set top boxes that turn
the TV into a web browser.