Easy Notes Of Data Communication and Computer Network unit-1 @Computer Diploma

Description

Unit I: Fundamentals of Data Communication and Computer Network

1.1 Process of Data Communication and its Components

Data communication is the exchange of data between two devices via some form of transmission medium.

The five fundamental components of a data communication system are:

1. Message: The information (data) to be communicated.

2. Transmitter (Sender): The device that sends the data message. It often converts the message into a format suitable for transmission.

3. Receiver: The device that receives the message. It converts the message back into a usable format.

4. Medium (Transmission Medium): The physical path through which the message travels from the transmitter to the receiver (e.g., copper wire, fiber optic cable, air).

5. Protocol: A set of rules that governs data communication. It dictates how the data is sent and received.

1.2 Protocols, Standards, and Rates

📝 Protocols and Standards

• Protocols: A protocol is a formal set of rules, conventions, and data formats that dictate how computers exchange information. Example: TCP/IP, HTTP.

• Standards: Agreed-upon rules providing guidelines to ensure data communication equipment and software from different manufacturers can work together. They are essential for creating and maintaining an open and competitive market.

• Standard Organizations: Bodies responsible for creating and approving these communication standards (e.g., IEEE – Institute of Electrical and Electronics Engineers, ISO – International Organization for Standardization, ITU-T – International Telecommunication Union-Telecommunication Standardization Sector).

📊 Data Rates

• Bandwidth: The range of frequencies a channel can pass. In digital terms, it often refers to the maximum data rate a path can handle, typically measured in bits per second (bps).

• Data Transmission Rate (Bit Rate): The number of bits transmitted per second, measured in bits per second (bps). This is the ultimate measure of how fast data is actually transferred.

• Baud Rate (Symbol Rate): The number of signal units (or symbols) transmitted per second. A signal unit can represent one or more bits. In the simplest case, 1 baud = 1 bps, but in complex modulation schemes, 1 baud can carry multiple bits.

  • Relationship: $Bit\ Rate = Baud\ Rate \times (\text{Number of bits per signal unit})$

1.3 Modes of Communication

The mode of communication refers to the direction of signal flow between two linked devices.

1.4 Analog Signal and Digital Signal, Analog and Digital Transmission

🌊 Analog vs. 🔢 Digital Signals

• • Analog Signal: A continuous, time-varying signal that takes on any value within a range. It is characterized by its amplitude, frequency, and phase. (e.g., human voice, traditional telephone lines).

  • Digital Signal: A discrete signal that has only a finite number of defined values, typically represented by two states (1 and 0). (e.g., computer data).

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🔄 Analog and Digital Transmission Conversion

The process of moving data across a medium often requires conversion:

• Digital-to-Analog Conversion (DAC): Necessary to send digital data (from a computer) over an analog communication link (like a telephone line).

  • Process: Modulation (techniques like ASK, FSK, PSK).

  • Device: Modem (Modulator/Demodulator).

• Analog-to-Digital Conversion (ADC): Necessary to convert an analog signal (like a voice call) into digital data for transmission over a digital network.

  • Process: Digitization (techniques like Pulse Code Modulation – PCM).

  • Device: Codec (Coder/Decoder).

1.5 Fundamental Of Computer Network

• Definition: A computer network is a system of interconnected independent computers that are able to share hardware and software resources and information.

• Need of Computer Network: To facilitate resource sharing, enhance communication, enable centralized management, and improve data access reliability.

• Applications: Email, World Wide Web (WWW), e-commerce, video conferencing, collaborative work (Google Docs, Slack), remote access.

• Network Benefits:

  • Resource Sharing: Sharing printers, scanners, and storage devices.

  • Communication: Fast and inexpensive inter-user communication (email, chat).

  • Cost Reduction: Centralizing expensive software/hardware.

  • Reliability: Files can be duplicated on multiple machines for backup.

1.6 Classification Of Network (Based on Scale)

Networks are classified primarily by their geographical coverage: