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Net 222: Communications and networks fundamentals ( Practical Part)

This tutorial covers the basics of data and computer communications networks, including twisted-pair copper wire, shielded and unshielded twisted pair, and optical fiber cable. It also discusses the use of modulation schemes for transmitting voice signals through radio.

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Net 222: Communications and networks fundamentals ( Practical Part)

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  1. Net 222: Communications and networks fundamentals (Practical Part) Tutorial 3: Chapter 4 Data &computer communications Networks and Communication Department

  2. Chapter 4 page 135 (Data & computer communications) • Review questions: • 4.1 • 4.3 • 4.4 • Problems: • 4.7 Networks and Communication Department

  3. Question • 4.1. Why are the wires twisted in twisted-pair copper wire? Networks and Communication Department

  4. Answer • The twisting of the individual pairs reduces electromagnetic interference. For example, it reduces crosstalk between wire pairs bundled into a cable. Networks and Communication Department

  5. Question • 4.3. What is the difference between unshielded twisted pair and shielded twisted pair? Networks and Communication Department

  6. Answer • Unshielded twisted pair (UTP) is ordinary telephone wire, with no form of electromagnetic shielding around the wire. Shielded twisted pair (STP) surrounds the wire with a metallic braid or sheathing that reduces interference. Networks and Communication Department

  7. Question • 4.4. Describe the components of optical fiber cable. Networks and Communication Department

  8. Answer • Optical fiber consists of a column of glass or plastic surrounded by an opaque outer jacket. The glass or plastic itself consists of two concentric columns. The inner column called the core has a higher index of refraction than the outer column called the cladding. Networks and Communication Department

  9. Answer(Cont.) • 4.7 The audio power of the human voice is concentrated at about 300 Hz. Antennas of the appropriate size for this frequency are impracticably large, so that to send voice by radio the voice signal must be used to modulate a higher (carrier) frequency for which the natural antenna size is smaller. • a. What is the length of an antenna one-half wavelength long for sending radio at 300 Hz? • b. An alternative is to use a modulation scheme, as described in Chapter 5, for transmitting the voice signal by modulating a carrier frequency, so that the bandwidth of the signal is a narrow band centered on the carrier frequency. Suppose we would like a half-wave antenna to have a length of 1 meter. What carrier frequency would we use? Networks and Communication Department

  10. Question Networks and Communication Department

  11. The End Any Questions ? Networks and Communication Department

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