ICT L6 ON COMPUTER NETWORK AND DATA COMMUNICATION
WEEK BEGINNING 23RD TO 27TH MARCH 2020
MR TUMBU
King David Comprehensive college Computer Networks & Data Communication
PREPARED BY TUMBU BARTHOLOMEW ELAD 1 | P a g e
CLASS: LOWER SIXTH
SUBJECT: ICT
DURATION: 2Hr
1. Benefits and Limitations Of Computer Networks 1.1. Benefits a. File sharing Networks allow files located on one system to be accessed remotely. In an organization, this saves employees from the hassle of carrying a storage device each time data has to be transported from one system to another. Furthermore, if files are stored on a server and all of its clients share that storage capacity, then it becomes easier to make a file available to multiple users.
b. Resource Sharing Networks allow resources like modems, printers and scanners to be shared amongst multiple users.
c. Communication Computer networks have improved the way people communicate. People all over the world can communicate and collaborate in a matter of minutes thanks to networks. In organizations, computer networks serve as the backbone of daily communication
d. Save costs Shared resources mean reduction in hardware costs. Shared files mean reduction in memory requirements which indirectly means reduction in file storage expenses.
e. Increased Storage Capacity A stand alone computer might fall short of storage memory, but when many computers are on a network, the memory of different computers can be used in such a case. One can also design a storage server on the network in order to have a huge storage capacity.
f. Teleworking Teleworking is the act of working from home and communicating with the office through the use of telecommunication equipment. This is possible because of networks. Working from home enables organizations to save cost of renting large offices, save money on furniture and IT equipment and pay their employees only when they are jobs or projects to do. On the other hand, employees have flexible working hours, they can attend to household chores and they save money on transport.
g. Teleconferencing Conferences can be held with participants found at different locations. This enables organizations to save travelling cost for employees. This is as a result of computer networks.
King David Comprehensive college Computer Networks & Data Communication
PREPARED BY TUMBU BARTHOLOMEW ELAD 2 | P a g e
1.2. Limitations a. Security concerns If a computer is a standalone computer, physical access becomes necessary for any kind of data theft. However, if a computer is on a network, a hacker can get unauthorized access by using different tools.
b. Malware attacks Computers connected to a network are susceptible to malware attacks. If one system gets infected by a virus, there is a possible for the other systems getting infected too.
c. Backup Issues On a network with distributed resources, it becomes difficult to backup data for security purposes.
I. Data Communication Data communication refers to the exchange of data between two devices via some form of communication channel. In data communication the following basic terms are frequently used: o Data: a collection of facts in raw form that becomes information after processing. o Signal: an electric or electromagnetic encoding of data. o Signaling: propagation of signals across a communication channel. o Transmission: sending of data from one place to another by means of signals.
1. Basic Elements Of a Communication System There are five basic components in a communication system. • Data Source: creates data for transmission • Transmitter: encodes data for transmission • Communication channel: connecting medium between communicating devices • Receiver: decodes transmitted data back to original • Destination: the final destination of the transmission
Example: John calls Peter on phone. The data source is John, the transmitter is John’s phone, the communication channel is the telephone cable or microwave, the receiver is Peter’s phone and the destination is Peter.
2. Data Transmission Concepts 2.1. Analog and Digital Signals Data is transmitted from one point to another by means of electrical signalsthat may be in analog or digital form.
a. Analog Signals An analog signal is one in which information is represented as a continuous variation of some physical property or quantity. Analog signals are continuous waves that carry information by varying the frequency or amplitude of the wave. ✓ When the amplitude of the signal is varied the technique is called amplitude modulation (AM)
King David Comprehensive college Computer Networks & Data Communication
PREPARED BY TUMBU BARTHOLOMEW ELAD 3 | P a g e
✓ When the frequency of the signals is varied, the technique is called frequency modulation (FM). Human speech is an example of an analog signal. Telephone lines use analog signals because they were originally designed for speech.
b. Digital Signals A digital signal is one in which information is represented as a sequence of binary values 0 and 1.These two values represent two conditions, on or off,corresponding to two known levels of voltage or current. Digital signals do not continuously vary as analog signals. Signals are transmitted within the computer as digital signals. Systems that use digital technology are known as baseband systems.
