Unit-X: Communication System
Part A: 30 Multiple Choice Questions (MCQs) with Answers
Which of the following is not a component of a communication system?
a) Transmitter
b) Receiver
c) Amplifier
d) Transmission medium
Answer:
c) Amplifier
The function of a transmitter is to:
a) Receive signals
b) Decode the message
c) Send the message signal
d) Modulate the wave only
Answer:
c) Send the message signal
Which one of the following signals has the highest bandwidth?
a) Speech signal
b) TV signal
c) Radio signal
d) Telephonic signal
Answer:
b) TV signal
Bandwidth of speech signal is approximately:
a) 3 kHz
b) 20 kHz
c) 200 Hz
d) 1 MHz
Answer:
a) 3 kHz
Which wave propagates through the ionosphere and reflects back to Earth?
a) Ground wave
b) Space wave
c) Sky wave
d) Surface wave
Answer:
c) Sky wave
Which wave is used in satellite communication?
a) Sky wave
b) Ground wave
c) Space wave
d) Surface wave
Answer:
c) Space wave
Modulation is necessary because:
a) It reduces noise
b) It helps in multiplexing
c) Low-frequency signals can't travel long distances
d) All of the above
Answer:
d) All of the above
In amplitude modulation (AM), which parameter of carrier wave is varied?
a) Frequency
b) Amplitude
c) Phase
d) Speed
Answer:
b) Amplitude
In frequency modulation (FM), which parameter is varied?
a) Frequency
b) Amplitude
c) Phase
d) None
Answer:
a) Frequency
Which has better noise immunity?
a) Amplitude modulation
b) Frequency modulation
c) Phase modulation
d) Pulse modulation
Answer:
b) Frequency modulation
Which modulation technique is used in commercial FM radio?
a) AM
b) PM
c) FM
d) PCM
Answer:
c) FM
What is the frequency range for voice signals?
a) 20 Hz to 20 kHz
b) 3 Hz to 3000 Hz
c) 100 kHz to 1 MHz
d) 200 kHz to 2 MHz
Answer:
b) 3 Hz to 3000 Hz
Which of the following uses ground wave propagation?
a) FM radio
b) AM radio
c) Satellite TV
d) Internet
Answer:
b) AM radio
What is the main advantage of FM over AM?
a) Lower cost
b) Simpler circuit
c) Better noise immunity
d) High power consumption
Answer:
c) Better noise immunity
What is the function of a transponder in satellite communication?
a) Receive signal only
b) Transmit signal only
c) Receive and retransmit signal
d) Decode signal
Answer:
c) Receive and retransmit signal
Which of the following is a geostationary satellite used for?
a) Weather forecast
b) Communication
c) Navigation
d) Both a and b
Answer:
d) Both a and b
Which frequency range is used in mobile communication?
a) VHF
b) UHF
c) SHF
d) ELF
Answer:
b) UHF
Which wave is not used for long distance communication?
a) Sky wave
b) Space wave
c) Ground wave
d) Microwave
Answer:
c) Ground wave
Which of the following is a digital signal?
a) Sine wave
b) Square wave
c) Triangular wave
d) Cosine wave
Answer:
b) Square wave
Which technology uses GPS?
a) Mobile phones
b) Smartwatches
c) Cars
d) All of the above
Answer:
d) All of the above
Which component of a communication system converts signals into suitable form for transmission?
a) Receiver
b) Transmitter
c) Antenna
d) Transducer
Answer:
b) Transmitter
Which wave propagation is most suitable for satellite communication?
a) Ground wave
b) Sky wave
c) Space wave
d) None
Answer:
c) Space wave
Which of these signals can travel longer distances without much attenuation?
a) Low-frequency signals
b) High-frequency signals
c) Ultrasonic waves
d) None
Answer:
b) High-frequency signals
Which one is not a transmission medium?
a) Coaxial cable
b) Optical fibre
c) Air
d) Diode
Answer:
d) Diode
In internet communication, what kind of signal is used?
a) Analog
b) Digital
c) Frequency modulated
d) Amplitude modulated
Answer:
b) Digital
Which communication uses binary data transmission?
a) Analog communication
b) Digital communication
c) Amplitude modulation
d) Frequency modulation
Answer:
b) Digital communication
Which one of the following is used to convert electrical signals into electromagnetic waves?
a) Transmitter
b) Receiver
c) Antenna
d) Decoder
Answer:
c) Antenna
The part of the electromagnetic spectrum used in satellite communication is:
a) X-ray
b) Visible light
c) Microwaves
d) UV rays
Answer:
c) Microwaves
Which of the following helps GPS determine your location?
a) Radar
b) Satellites
c)
Fiber
optics
d) Microwave tower
Answer:
b) Satellites
Which type of modulation is preferred for music transmission?
a) AM
b) FM
c) PM
d) PCM
Answer:
b) FM
Part B: 30 Short Answer Questions with Answers
Name the basic elements of a communication system.
Answer:
Transmitter, transmission medium, and receiver.
What is the need for modulation?
Answer:
To reduce antenna size, increase range, avoid mixing of signals, and allow effective transmission.
What is the frequency range of speech signals?
Answer:
Approximately 300 Hz to 3.4 kHz.
Define bandwidth.
Answer:
Bandwidth is the difference between the highest and lowest frequencies of a signal.
What is the typical bandwidth for a TV signal?
Answer:
Around 6
MHz.
Define ground wave propagation.
Answer:
Propagation of radio waves along the surface of Earth.
What is sky wave propagation?
Answer:
Propagation of radio waves reflected by the ionosphere.
What is space wave propagation?
Answer:
Propagation of waves directly from transmitter to receiver through atmosphere.
Define amplitude modulation.
Answer:
A process in which the amplitude of carrier wave is varied in accordance with the message signal.
Define frequency modulation.
Answer:
A process in which the frequency of the carrier wave is varied according to the modulating signal.
Why is FM preferred over AM?
Answer:
Because FM has better noise immunity and provides better sound quality.
What is a transponder?
Answer:
A device that receives a signal, amplifies it, and retransmits it at a different frequency.
What is GPS used for?
Answer:
For navigation and accurate location tracking.
What is the bandwidth of digital data signals?
Answer:
Depends on data rate, generally very high.
What are
analog
and digital signals?
Answer:
Analog signals vary
continuously,
digital signals have discrete levels.
Name two common applications of satellite communication.
Answer:
Television broadcasting and internet connectivity.
Why is modulation index important?
Answer:
It determines the extent of modulation and affects signal quality and bandwidth.
What is the use of an antenna?
Answer:
It transmits and receives electromagnetic signals.
Which wave is used in microwave communication?
Answer:
Space wave.
Name two frequency bands used in mobile communication.
Answer:
900 MHz and 1800
MHz.
What is the basic difference between AM and FM?
Answer:
AM varies amplitude, FM varies frequency of the carrier wave.
What is the range of UHF band?
Answer:
300 MHz to 3 GHz.
What is meant by line-of-sight communication?
Answer:
Communication where transmitter and receiver are in direct visual path.
What is multiplexing?
Answer:
A technique to send multiple signals over a single communication channel.
What are the uses of microwaves?
Answer:
In satellite communication, radar, and mobile phones.
What do you mean by digital communication?
Answer:
Communication using digital signals (binary format).
What is the advantage of digital signals?
Answer:
Better noise immunity, easier to process and store.
Why do we use repeaters in communication?
Answer:
To amplify and retransmit signals to cover long distances.
What is internet?
Answer:
A global network of computers enabling communication and data exchange.
How does GPS work?
Answer:
It works by calculating position using signals from at least four satellites.
