1st Year NotesComputer class 11th

1st year Computer Chapter 3 Data communications

1st year Computer Chapter 3 Data communications Question an Answer

Shorts and Simple Question an Answer

Q1. What is data communication?

Ans.Data communication is the process of electronically transferring data from one place to another, facilitated by transmission media and communication devices.

Q2. What are the basic elements of data communication?

Ans. The fundamental components of data communication include sending and receiving devices, communication devices, and the transmission medium.

Q3. What is communication media in data communication?

Ans. Communication media, also known as communication channels, are the paths through which data is transmitted. Examples include telephone lines, twisted pair wires, coaxial cables, fiber optic cables, microwave, and satellites.

Q4. What are the two main types of communication media?

Ans. Communication media are categorized into two main types: physical transmission media (bounded media) and wireless transmission media (unbounded media).

Q5. Can you explain physical transmission media with examples?

Ans. Physical transmission media involve directly connecting communication devices with physical media. Examples include twisted pair wires (used in LAN), coaxial cables (used by cable TV and telephone companies), and fiber optics (used by telephone companies, ISPs, and cable TV operators).

Q6. Describe wireless transmission media and provide examples?

Ans.Wireless transmission media allow communication devices to exchange data through the air or space, using radio signals, microwave signals, and infrared signals. Examples include microwave transmission (utilizing high-frequency radio waves), communication satellites (space stations sending and receiving data), and mobile communication (radio-based networks for mobile computers).

Q7. What is modulation in data communication?

Ans.Modulation is the process of converting digital signals into analog form to facilitate data transmission. It combines data or message signals with carrier waves or signals, allowing information to be transmitted through space as electromagnetic waves.

Q8. What are three basic methods of modulation, and how do they work?

Ans. Three fundamental modulation methods are:

  1. Amplitude Modulation (AM): Modifies the carrier wave’s amplitude to represent binary digits 1 (presence of the carrier wave) and 0 (absence of the carrier wave). Commonly used in AM radio broadcasts.
  2. Frequency Modulation (FM): Alters the carrier wave’s frequency to represent binary digits 0 (original carrier frequency) and 1 (higher frequency). Commonly used in radio transmissions.
  3. Phase Modulation (PM): Varies the phase of the carrier wave to represent binary digits 1 and 0, similar to frequency modulation.

Q9. What are the basic elements of a data communication system?

Ans. The fundamental elements of a data communication system include:

  1. Sender/Transmitter (e.g., computer or telephone)
  2. Message (data or information to be transmitted)
  3. Medium or Communication Channel (path for data transmission, e.g., telephone line or fiber optics)
  4. Receiver (e.g., computer, telephone, or printer)
  5. Encoder and Decoder (used to convert signals between different forms)

Q10. How do asynchronous and synchronous transmissions differ?

Ans. Asynchronous Transmission:

  • Data is sent character by character.
  • Data is not stored before transmitting.
  • May have gaps between transmitted characters.
  • Uses start and stop bits to control information transmission. Synchronous Transmission:
  • Data is transmitted block by block or word by word.
  • Data is stored before transmission.
  • No gaps between transmitted characters.
  • Relies on clock signals for information transmission control.

Q11. What’s the difference between Narrow Band and Broad Band in data communication?

Ans.Narrow Band:

  • Low-speed transmission, typically 40 to 300 bps or baud.
  • Used for low-speed teletypewriter communication and similar devices. Broad Band:
  • High-speed transmission, capable of rates around 56,000 bps or baud.
  • Utilized when significant amounts of data need to be transmitted at high speeds.

Q12. What is meant by Simplex and Half-Duplex modes of communication?

Ans. Simplex Mode:

  • Data flows in only one direction; unidirectional.
  • Devices can either send or receive data but not both simultaneously.
  • An example is traditional television broadcasting. Half-Duplex Mode:
  • Data can flow in both directions but not simultaneously.
  • Devices can send or receive data but not at the same time.
  • Internet surfing, where users send requests and receive web pages one at a time, is an example of half-duplex communication.

Q12. Why is Fiber Optic cable used for communication?

Ans.Fiber Optic cable is chosen for communication because it offers high-speed data transmission (usually 1Gbps to 2Gbps) and is not affected by electromagnetic interference. Its optical properties, like refraction, enable the transmission of data as light waves. Many telephone and cable TV companies employ fiber optic cables for communication, making it a preferred choice for modern communication systems.

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