Communication Engineering Basics

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Questions and Answers

What is the primary purpose of modulation in communication engineering?

To decode data at the receiver end

To convert information into a signal for transmission (correct)

To reduce noise in received signals

To increase the frequency of signals

Which of the following is NOT considered a part of general communication systems?

Data storage unit (correct)

Receiver

Transmitter

Transmission medium

What are some common problems encountered by communication channels?

Compression and encryption

Attenuation and distortion (correct)

Analog and digital conversion

Interference and modulation

Which type of communication channel is classified as wireline?

Twisted Pair (D) Signup and view all the answers

What limitation often constrains the amount of data transmitted over communication channels?

Power and bandwidth constraints (B) Signup and view all the answers

In what frequency range can electromagnetic waves be selected for information transfer?

Radio frequencies up to optical range (B) Signup and view all the answers

Which of the following communication systems is used for navigation?

Satellite Communications & GPS (A) Signup and view all the answers

What does the receiver in a communication system do?

Converts the transmitted signal back into original information (D) Signup and view all the answers

Which type of communication medium provides the highest bandwidth?

Optical Fiber (C) Signup and view all the answers

What is the primary application of coaxial cable in communication?

Cable TV and Broadband (A) Signup and view all the answers

Which message type represents information using discrete values?

Digital Messages (B) Signup and view all the answers

What factor primarily influences indoor wireless channels?

Furniture and Walls (C) Signup and view all the answers

Which communication medium has a low installation cost?

Copper Wires (B) Signup and view all the answers

Which frequency band is typically used for traditional wireless communication?

Radio Frequency (B) Signup and view all the answers

Which type of cable is primarily used for high-speed data communications?

Optical Fiber (A) Signup and view all the answers

What characteristic of waveguides makes them difficult to install?

Size and Complexity (B) Signup and view all the answers

What is the primary advantage of using optical fiber cable over other types of wireline channels?

Higher bandwidth and lower signal attenuation (A) Signup and view all the answers

Which wireline channel type is considered the oldest and most common?

Copper Wire (B) Signup and view all the answers

What is a key limitation of copper wire as a wireline channel?

Limited bandwidth of several hundred kilohertz (A) Signup and view all the answers

What type of wireline channel uses a hollow metal tube to transmit microwaves?

Waveguide (A) Signup and view all the answers

Which wireline channel type was first used commercially in the 1940s for connecting telephone exchanges?

Coaxial Cable (B) Signup and view all the answers

What is the main disadvantage of waveguides compared to other wireline channels?

Higher cost and difficulty of installation (C) Signup and view all the answers

What year did Corning Glass Works announce the development of optical fiber?

1970s (B) Signup and view all the answers

Which wireline channel was first used for television signal transmission in the 1950s?

Coaxial Cable (D) Signup and view all the answers

What is the primary purpose of carrier modulation?

To allow the message signal to be transmitted more efficiently over a communication channel (A) Signup and view all the answers

Which of the following modulation techniques is classified as digital modulation?

Phase Shift Keying (PSK) (A) Signup and view all the answers

What analogy is used to describe the role of the carrier signal in modulation?

A stone wrapped in paper to be thrown (A) Signup and view all the answers

In the sinusoidal function representing a carrier signal, what does the variable 𝜙 represent?

Phase of the signal (B) Signup and view all the answers

What challenge does modulation help overcome regarding antenna size?

The impractically large antenna for low-frequency signals (C) Signup and view all the answers

Which type of modulation uses digital signals?

Frequency Shift Keying (FSK) (C) Signup and view all the answers

Why is modulating a low-frequency signal advantageous for transmission?

It shifts the signal to a more manageable frequency for transmission. (A) Signup and view all the answers

What frequency range is typically concentrated in a speech signal?

100 to 3000 Hz (A) Signup and view all the answers

What is the primary function of a digital modulator?

To convert discrete symbols into an analog waveform for transmission (B) Signup and view all the answers

In binary modulation, what does each binary digit correspond to?

One waveform only (D) Signup and view all the answers

What role does the communication channel play in digital communication?

It filters, attenuates, and distorts the transmitted signal (B) Signup and view all the answers

What is the main goal of a digital demodulator?

To produce decisions on transmitted symbols from received analog waveforms (B) Signup and view all the answers

What does the channel decoder aim to produce?

An estimate of the original information symbols (A) Signup and view all the answers

Why is digital technology preferred over analog technology in communication systems?

Digital systems can accurately recover information from noisy signals (A) Signup and view all the answers

What function do regenerative repeaters serve in a digital system?

They detect incoming pulses and retransmit new ones to mitigate noise (A) Signup and view all the answers

What challenges do analog signals face compared to digital signals at the receiver end?

Analog signals can exhibit fine details that are crucial for recovery (D) Signup and view all the answers

What technique allows multiple signals to be transmitted simultaneously in the same area without interference?

Frequency division multiplexing (C) Signup and view all the answers

Which part of a digital communication system is responsible for converting an analog signal into binary digits?

A/D converter (A) Signup and view all the answers

What is the primary purpose of channel encoding in a digital communication system?

To introduce redundancy for error correction (C) Signup and view all the answers

What type of communication system primarily uses analog modulation techniques?

Analog communication system (A) Signup and view all the answers

In digital communication, what does the term 'code rate' refer to?

The ratio of the number of bits in a code word to the number of bits in the original message (C) Signup and view all the answers

What is a likely characteristic of an analog communication system compared to a digital system?

The transferred information can take on a continuum of values (B) Signup and view all the answers

What component is responsible for reversing signal modifications in the receiver of a digital communication system?

Decoder (C) Signup and view all the answers

Which of the following best describes the role of a source encoder in a digital communication system?

To eliminate unwanted redundancy in the information (A) Signup and view all the answers

Study Notes

Introduction to Communication Engineering

Communication is the transfer of data from a source to a destination across a channel.
This transfer aims for speed and efficiency, encompassing signals like audio, video, and digital data.
Information is often modulated onto an electromagnetic wave (EMW) acting as a carrier.
Multiple communication systems exist, including telegraph, telephony, cellular networks, wireless networks, audio/video broadcasting, satellite communication, and GPS, and optical communication.

General Communication System

A communication system consists of a transmitter, transmission channel, and receiver linked to a destination.
The transmitter takes information and converts it into a transmittable signal.
The receiver converts the received signal back into the original information.
The channel is the physical medium through which the signal travels.

Communication Channels

The channel carries the signal, but various issues can occur, like attenuation, distortion, and interference.
Problems like attenuation, amplitude and phase distortion, and multipath distortion affect the signal.
Practical limitations such as bandwidth and power limits constraint the amount of reliably transmitted data on a channel.
Wireless and wireline are two channel classifications.

Wireline Channels

Copper wire is a common and older wireline technology.
Coaxial cable offers higher bandwidth compared to copper wire, but installation is more complex.
Waveguides are used primarily for microwaves and offer very high bandwidth, but are also expensive and challenging to install.
Optical fiber cables transmit data via light and provide very high bandwidth over long distances with low signal attenuation, but are more costly and harder to install.

Wireless Channels

Wireless communication uses electromagnetic waves (EMWs) without physical cables.
Interference can occur due to simultaneous transmissions from different sources.
Wireless channels are classified based on frequency bands like radio frequency, microwaves, and optical frequency bands.

Message Signal

Message signals carry the information to be transmitted.
Analog messages are continuous signals (e.g., audio, video).
Digital messages are discrete signals (e.g., teletype machine output). Often represented as binary signals.

Carrier Modulation

It's the process where a message signal modulates a carrier signal, enhancing transmission by shifting frequency characteristics.
Analog modulation (amplitude, frequency, and phase modulation) techniques transform signals for efficient transmission.
Digital modulation (amplitude, frequency, and phase shift keying) are used to transmit digital data via carrier signals.

Why Modulation?

Ease of Transmission: Channels act as bandpass filters which filter the signal and allows it to transmit over the required frequency.
Ease of Radiation: Antennas are a fraction of the radiating signal’s wavelength, and modulation allows smaller antennas for practical use.
Transmission of Multiple Signals: Signals can be transmitted simultaneously using separate frequency sections.

Digital Communication System

Digital communication relays information using binary digits (bits).
A block diagram shows its basic elements: a source, encoder, modulator, channel, demodulator, decoder, and destination.
Digital modulation methods convert digital signals to analog signals suitable for transmission over a channel.

Why the World is Going Digital

Digital technology is replacing analog technology due to its high speed performance using digital circuits.
The nature of digital signals allows for high noise immunity and robustness during transmission.
Digital signals facilitate efficient data handling and processing. Signal regeneration can occur in repeaters to eliminate distortions and noise.

Electromagnetic Spectrum

Electromagnetic waves are categorized by their frequency, wavelength, and characteristics in an electromagnetic spectrum.
Different frequencies and wavelengths in the spectrum find diverse applications, from radio to optical frequencies.

Source Encoding

Source encoding efficiently represents information in binary form, eliminating redundancy for efficient data transmission.

Channel Encoding

Introducing controlled redundancy in signals through channel encoding helps the receiver compensate for channel imperfections (like noise and interference) during reception.

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Description

Test your knowledge on the foundational concepts of communication engineering. This quiz covers modulation, communication channels, and various transmission media, helping you understand their roles and limitations. Perfect for students and professionals alike!