Page 65 - DCAP207_NETWORKS_DCAP406_COMPUTER_NETWORKS

Computer Networks/Networks

Notes Downlink Frequency: It is the frequency used to transmit the signal from satellite to earth
station.
Local Loop: Two sets of wires create a duplex connection between the subscriber’s premises and
the CO over which an analog electrical signal is passed.
Microwave Radio: It is a form of radio transmission that uses ultra-high frequencies.
PSTN: It may be referred as a public communication system that provides local, extended local
and long distance telephone service to the subscribers.
Radio: A technique where data is transmitted using radio waves and therefore energy travels
through the air rather than copper or glass.
Trunk Line: It refers to the high-speed digital connection between telephone and CO in the
PSTN.

Uplink Frequency: It is the frequency used to transmit signal from earth station to satellite.
Very Low Frequency: It uses electromagnetic radiation generated in the low frequency band of
3-30 kHz.

4.8 Review Questions

1. Describe how satellite communication is different from radio broadcast?
2. Write down any two advantages and disadvantages of using satellite communication.
3. How do cells in mobile communication ensure a low probability of call droppings?

4. How is the microwave signal strengthened to its maximize value to increase the distance
of transmission at acceptable levels?

Answers: Self Assessment

1. 5 2. 4
3. 1 4. 3

5. 2 6. c =
7. Multipath fading 8. Ground stations
9. To avoid interference 10. Trunk
11. Cell site 12. 16-24 Km

13. Satellite

4.9 Further Readings

Books Andrew S. Tanenbaum, Computer Networks, Prentice Hall
Behrouz A. Forouzan and Sophia Chung Fegan, Data Communications and
Networking, McGraw-Hill Companies

Rajneesh Agrawal and Bharat Bhushan Tiwari, Computer Networks and Internet,
Vikas Publication

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