Unit 3 Data Communication Assignment 2

MCQ’s

Sr Question A B C D
1 Process of transfer data electrically Data Data sender Data Data
from one place to another is called processing communication sequencing
2 All of the following are element of data Sender receiver Medium Voltage
communication system except
3 Physical path that connects the source Encoder Decoder Communication Self –testing
and receive is known as channel
4 The electromagnetic or light waves Information Signal Sender Frequency
representing data are called
5 The music and speech are the example Image Video Numeric Audio
of following data
6 Which of the following is a 4-bit ASCII BCD EBCDIC Unicode
coding scheme?
7 BCD stands for Byte coded Base coded Binary coded Bi code
decimal decimal decimal decimal
8 BCD code is a bit code 2 bit 4 bit 6 bit 8 bit
9 ASCII code is bit code 3 4 6 8
10 How many characters ASCII 7-bit can 128 256 1024 32
represent?
11 EBCDIC is a bit code 4 6 7 8
12 A telephone is the example of Simplex Half duplex Full duplex None of these
mode
13 Which of the following is the fastest Half duplex Full duplex Simplex None of these
communication mode
14 Analog signal is measured in Volt Hertz Watts Digits
15 Which of the following transmit voice Twisted pair Coaxial Fiber optic cable Microwave
and data through air as high-frequency cables
radio waves
16 Which of the following features is Speed Self –testing Transmission All of these
provided with a modem? rate
17 Example of numeric data 5.2 6.4 5567 All of these
18 Digital signals are commonly called are Broadband Base band Narrowband Frequency
19 A type of communication that sends Isochronous Synchronous Asynchronous Monochrono
data using flow control to synchronize transmission transmission transmission us
data between sender and receiver transmission
20 All of the following are guided Twisted pair Fiber optic Coaxial cables Microwave
communication media except cable

SHORT QUESTIONS
1. Define data communication?
Data communication is exchange of data between two devices through a transmission media. It is the process
of transferring data electronically from one place to another.
2. List different elements or components of data communication?
The five component of data communication are:
 Message
 Sender
 Receiver
Unit 3 Data Communication Assignment 2

 Communication channel
 Encoder and decoder
3. Define receiver?
Receiver is a device that receives message or data. It is also called sink or destination. It can be workstation,
tv or mobile phone etc.
4. Different between encoder and decoder?
Encoder Decoder
An encoder is a device that converts A decoder is a device that converts encode
digital signals into a form which can pass signals receives from a transmission medium
through a transmission medium or or channel into digital from which is
channel. understandable by receiver.
5. What is signal?
A system as referred to in communication systems, signal processing, and electrical engineering “is a function
that conveys information about the behavior or attributes of some phenomenon or term”. Electromagnetic or
light waves that represent data is called signals.
6. Define analog signal and its characteristics?
An analog signal is a continuous electrical signal in wave from that varies or charges in time. This is called
carrier wave. It measure in volts. EX: sound waves.
Characteristics:
The characteristics are frequency and amplitude.
 The number of time a wave repeats during a given time period is called frequency.
 The height of wave within a given time period is called amplitude.
7. Define digital signal?
Digital signals are in non-continuous or discrete form. They consist of plus with discrete levels or values.
Digital signals are faster. It is a sequence of voltage represented in binary form.
8. How data represented inside the computer?
Data is represented inside the computer by means of binary numbers. Computer works with binary numbers.
Binary numbers means 0 or 1. The data inside the computer is represented as electrical plus.
9. What is meant by encoding of data?
Computer works only with binary numbers or digits. It stores all type of data in the form of binary digits. The
data, numeric or non-numeric must be converted to binary form before it is store inside the computer by using
different coding schemes or methods.
10. What is UNICODE?
Unicode stands for Universal Code. It is a 16-bit code and can represent up to 65,356 symbols and characters.
As it can represent more character than any other code, it is used to represent characters of languages such as
Urdu, Japanese, Chinese, Arabic, etc. It can represent the characters of all major languages of the world. It is
started to replace ASCII at all levels.
11. Define data transmission or data communication modes?
It communication modes refers to the ‘number of elementary units of data that can be simultaneously
translated by the communications channel’. The way in which data is transmission from one place to another
is called data transmission mode or the direction of flow of data between two communicating devices is called
Data Communication Mode.
12. Define half duplex mode and full duplex?
Half duplex Full duplex
In Half-Duplex mode, data can be Full duplex mode, data is transmitted in
transmitted in both direction but only in both directions at the same time. Full
one direction at a time. Data is sent and duplex mode is faster than half duple,
received in turns. A device with half- because time is not wasted in charging the
duplex mode can send and receive data but direction of data flow. EX: Telephone
not at the same time. system. Full-duplex transmission can be
Unit 3 Data Communication Assignment 2

The speed of half-duplex mode is slow. made possible by special device called
Example: Multiplexers
Internet surfing Example:
Walkie talkie Telephone system
13. What do you know about parallel data transmission and series data transmission?
PARALELLEL DATA Serial DATA TRANSMISSION
TRANSMISSION
In telecommunication and computer Transmitting data one bit at a time is called
science, parallel communication is method serial data transmission. Bits of data flows
of conveying multiply binary digits (bit) continuously i.e. one bit after the other
simultaneously. Parallel data transmission through a communication medium or
occurs when several bits of a data item are channel. Telephone lines use this method
transmitted simultaneously each along its of data transmission.
on separate channel. Example:
Example: Communication between keyboard and
Communication between Computer and computer.
printer
14. Different between asynchronous and synchronous transmission?
Asynchronous Synchronous
In this type of transmission of data is sent In this type of transmission, a clock is used
using flow control rather than a clock to to control the timing of bits being sent.
synchronize data between the source and It is more efficient
destination. There are no gap between characters being
It is less efficient transmitted.
There are gap between characters being Example:
transmitted Typing characters through keyboard
Example:
Video conferencing

15. Differentiate between baseband and broadband?

Baseband Broadband
It is a communication technique in which It is technique of transmitting a large
digital signals are placed onto the amount of data, voice and video over long
transmission line without change in distance s simultaneously by modulation
modulation. each signal onto a different frequency.
16. Name commonly used guided media or bounded media?
Commonly used guided media include coaxial cables, twisted pair wires, and fiber optic cables.
17. Write down the main advantages or disadvantages of fiber optic cable?
Advantages Disadvantages
It can carry more signals. It provides fast A major disadvantage of fiber optic cable
data transmission. It is less affected by is its high cost. It is also difficult to install,
external electromagnetic waves and maintain and it cannot carry signals over
provides better security of signals. great distance.
18. Define satellite communication?
Communication satellite is a space station. It receive microwave signal from earth stations, amplifies or
increases the signals and retransmits them back to earth. It is established in space about 23,300 miles above
the earth
19. List three features of modem?
Modems can be characterized by the following features or properties:
 Transmission rate: It indicates how many bits per second a modem is capable of transmitting or receiving.
Unit 3 Data Communication Assignment 2

 Speed: it is the rate at which a modem can send data. Modem speeds are 300 bps to 56kbps.
 Self-testing: it can test the digital connection with computer and also test analog connection with remote
modem.
 Voice over data: it also provides the facility of voice conversation while data is being transmitted.
 Error control: it has the feature of controlling errors for transmitting data.
20. What is modulation?
The process of conversion (or encoding) of digital signals into analog form for transmission is called
Modulation. It is done for transmission of data over telephone lines. Computer store, process and transmit
data in digital form. Modem is an example of a device that does modulation. Since a modern transmits data
using telephone lines, so data is converted from digital to analog form.
21. What External modem?
External Modem is attached to the system unit as an external device through telephone line. This modem is
connected to computer using serial cable to COM1 or COM2 port. It needs external power supply or
electricity. It is easy to maintain and use.
22. Define mobile communication?
Mobile communication is talking, texting, sending or receiving images files or data
over the wireless network.
An example of mobile communication is chatting on cell phone with your friends.
23. Give two examples of analog data?
i. The sound waves that you mouth produces when you speak are analogue- the waves vary in a smooth
way. These waves are converted into an electrical signal by a microphone.
ii. Analogue data use values that change very smoothly. ”A good example of this is an analogue clock.

LONG QUESTION
1. Define data communication also explain component of data communication.
2. Explain guided media and unguided media.
3. Define encoding of data also explain its types.
4. Explain modes of data transmission.
5. Briefly describe the types of data transmission.