Data Communication Concepts: An Overview, Slides of Information Technology

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Data Communication Concepts

Meraj Alam

Understanding the concept of transferring data

between devices

Introduction to Data Communication

Data communication is the process of sending or receiving electronic or digital data between two or more devices over a communication channel, like cables, optical fibers, or wireless media

Components of Data Communication:

● Message: The actual information (e.g., text, images, audio, video) to be transmitted. ● Sender: The device that originates and sends the message. ● Receiver: The device that receives the message. ● Transmission Medium: The physical path, such as cables or radio waves, over which the message travels. ● Protocol: A set of rules that govern how data is communicated, ensuring that all devices involved can understand and interpret the exchange.

Modes of data transmission

Data transmission can occur in three primary modes, defining the direction of data flow:

● Simplex: Unidirectional communication where data flows in only one direction. Examples include a keyboard sending data to a computer or a radio broadcast.

● Half-duplex: Bidirectional communication where devices can both send and receive data, but not at the same time. A walkie-talkie is a classic example.

● Full-duplex: Bidirectional communication where devices can send and receive data simultaneously. A telephone call is a common example.

Types of transmission media

The communication channel can be either guided or unguided:

● Guided (Wired) Media: Physical connections that guide data signals. ○ Twisted-Pair Cable: Two insulated copper wires twisted together to reduce interference. Used in telephone lines and older LANs.

○ Coaxial Cable: A central copper conductor surrounded by an insulating layer and a metallic shield. Commonly used for cable television.

○ Fiber-Optic Cable: Transmits data as pulses of light through a glass or plastic fiber. Offers high bandwidth over long distances.

Data Representation: Analog vs Digital

Analog data is a continuous stream of information that perfectly mirrors the real-world phenomenon it represents, without any gaps or breaks. It is described by smooth, continuous waveforms

Characteristics:

● Continuous values: Can take on any value within a given range. For example, a thermometer with mercury shows a continuous rise in temperature. ● Direct representation: An analog signal is a direct electrical representation of a physical quantity, such as sound pressure or light intensity. ● Lower quality: With each duplication or transmission, analog signals degrade slightly and are more susceptible to noise and interference, which can distort the signal.

Examples: Sound waves, Cassette tapes, Analog clocks, Traditional thermometers

Digital Data Representation

Digital data represents information using discrete, distinct, and finite values, typically in a binary format (1s and 0s).

Characteristics:

○ Discrete values: Data is represented by a limited set of specific values. In computing, this is a sequence of 1s (on) and 0s (off). ○ Encoded representation: The digital signal is an approximation of the original data. For example, a curve is represented by a series of small, discrete steps. ○ Higher quality: Digital signals are more resistant to noise. With signal regeneration, data can be copied and transmitted over long distances without quality loss. ○ Efficient: Digital data can be easily encrypted, compressed, stored, and manipulated.

Examples: Computer data, Compact discs (CDs), Digital clocks

Performance Measures: Data Transfer & Bandwidth

Bit rate: The amount of data transmitted from a source to a destination in a specified period of time

Bandwidth: The maximum volume of data that can be sent over a network connection in a given amount of time.

Throughput: The actual amount of data successfully transferred over a network in a specific period of time.

Latency: The delay that data experiences as it travels from a source to a destination, measured in milliseconds (ms).

Questions?