Most Important Communication Systems Exam Questions with Answers
FAQs on Communication Systems Practice Paper for Students
1. What are the main types of modulation used in communication systems?
Modulation in communication systems can be broadly classified into analog and digital types. The main types include:
- Amplitude Modulation (AM): Varies the amplitude of the carrier signal.
- Frequency Modulation (FM): Changes the frequency of the carrier wave.
- Phase Modulation (PM): Alters the phase of the carrier wave.
- Pulse Code Modulation (PCM): Used in digital communication for signal conversion and transmission.
2. What is a communication channel?
A communication channel is a medium that transmits information from a sender to a receiver.
- It can be wired (optical fibers, coaxial cables, twisted pair) or wireless (radio, microwave, satellite).
- Channel choice affects the speed, bandwidth, and quality of communication.
3. What is the difference between analog and digital signals in communication systems?
Analog signals are continuous-time signals that vary smoothly, whereas digital signals have discrete levels or values.
- Analog signals: Vary continuously (example: voice signals).
- Digital signals: Represented by binary values (0s and 1s).
- Digital systems offer better noise immunity and are widely used in current communication systems.
4. Explain the need for modulation in communication systems.
Modulation is essential to efficiently transmit signals over large distances.
- It increases the range of transmission.
- Reduces the effect of noise and interference.
- Allows multiplexing (multiple signals over a channel).
- Matches the frequency of message signals to be suitable for transmission.
5. What is bandwidth in communication systems?
Bandwidth is the range of frequencies a communication channel can transmit.
- It is measured in Hertz (Hz).
- Higher bandwidth enables faster data transfer rates.
- Examples: Voice calls (3 kHz), TV broadcast (6 MHz).
6. Distinguish between simplex, half-duplex, and full-duplex communication modes.
The three basic transmission modes in communication systems are:
- Simplex: Unidirectional communication (e.g., TV broadcast).
- Half-duplex: Two-way communication, but not simultaneously (e.g., walkie-talkies).
- Full-duplex: Two-way simultaneous communication (e.g., telephone).
7. What are the essential elements of a communication system?
A basic communication system consists of three major elements:
- Transmitter: Converts information into a signal suitable for transmission.
- Channel: Medium used for transmission.
- Receiver: Converts received signals back into usable information.
8. What is meant by attenuation in communication systems?
Attenuation is the loss of signal strength as it travels through a communication channel.
- Expressed in decibels (dB).
- Caused by distance, interference, and obstructions.
- It is a critical factor affecting signal quality in communication networks.
9. How does noise affect communication systems?
Noise is any unwanted signal that interferes with the transmitted message.
- It reduces signal-to-noise ratio (SNR).
- Causes errors in data reception.
- Common sources: thermal, atmospheric, and man-made noise.
10. What are the advantages of digital communication over analog communication?
Digital communication offers several key advantages over analog, making it widely used today:
- Higher noise immunity.
- Easy encryption and error correction.
- Efficient multiplexing and storage.
- More reliable and secure transmission.






















