IT438 Communication Systems Quiz

Course Information

• Course Title: Information Technology
• Course Number: IT438
• Instructor: Kamal Hamza, PhD
• Semester: Fall 2024-2025
• Materials Acknowledgment: The presentation includes figures and text from Data Communications and Networks by W. Stallings

Introduction

• Communication: The process of exchanging information between a source and a destination.
• Communication also refers to sending, receiving, and processing information from one point to another.

Communication Systems Components

• Components of any communication system include a transmitter, receiver, and communication channel.
• The transmitter formats the information for transmission over the channel.
• The source is the origin of data or information.
• The information source generates and transmits messages
  • Messages can be voice, pictures or computer keyboard input
  • Non-electrical signals need converting to electrical signals via a transducer

Communication System Components (Cont.)

• Source encoder/decoder: The source encoder converts the source's signal into a digital format to remove redundancy and efficiently represent the original signal using the least possible bits.
• The source encoder/decoder converts analog signals to digital formats and compresses data like audio (MP3) or any other type.
• Channel encoder/decoder: The channel encoder maps the digital signal to another to minimize noise. It adds redundancy to detect and fix errors during transmission through noisy channels
• Modulator: Improves signal transmission through channels by modifying signal parameters (amplitude, phase, frequency).

Examples of Guided Communication Channels

• Twisted pair (e.g., telephone wires) — twisted wires together inside cables
• Coaxial cable
• Optical fiber (e.g., fiber optic cables)—light signals.

Examples of Unguided Communication Channels

• Radio waves
• Microwaves
• Satellites
• Infrared

Why Different Types of Communication Systems?

• Factors influencing communication type choice:
  • Communication channel nature
  • Application nature (e.g., mobile apps require wireless)
  • Required signal quality
  • Cost

Problems that Face Communication Systems

• Noise: Unwanted signals from the environment.
• Interference: Superposition of multiple signals.
  • Interference could also be a malfunctioning system.
• Jamming: Intentional obstruction of the signal's quality

Problems that Face Communication Systems (Cont.)

• Problems illustrated by diagrams of pulse degradation of signals as they travel over longer distances.
• Signal degradation and regeneration

Data versus Signal

• Data refers to the information itself (e.g., speech, text, images) that the application generates.
• A signal is how the data is represented during transmission in the communication system.
• A speech signal in a microphone is different from the data (what you are saying).

Types of Data and Signals

• Possible combinations of data and signals (e.g., analog data with analog signal)
• This depends on the application nature
  • Analog data, Analog signal (Traditional telephone)
  • Analog data, Digital signal (VoIP, Digital music streaming)
  • Digital data, Analog signal (Modems, Optical Fiber Networks)
  • Digital data, Digital signal (Ethernet, Wi-fi, Modern computer networks)

Signal Representation in Time Domain

• Signals can be either continuous or discrete (quantized).
• Continuous: Signal intensity smoothly changes over time
• Examples would be a sine wave
• Discrete: Signal intensity remains constant for a period of time then changes to another constant level.
  • Examples would be a square wave
• Various signal shapes including sine waves, square waves, etc

Signal Representation in Time Domain (Cont.)

• Sine waves:
  • Amplitude—the maximum value of the wave.
  • Frequency—the number of cycles per second (Hz).
  • Period—the time it takes for one cycle.
  • Phase—the starting position of the wave.
  • Mathematical equations to define Sine waves: s(t) = A sin (2π ft+ $).

Test your knowledge on the key components of communication systems. This quiz covers topics such as transmitters, receivers, and channels based on the course materials from Data Communications and Networks. Prepare to assess your understanding of how information is exchanged and processed.