HSC Science (Computer Science) 12th Board ExamMaharashtra State Board

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Write a short note on MODEM. - HSC Science (Computer Science) 12th Board Exam - Computer Science 2

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Write a short note on MODEM.


(1) Computers store digital data, while telephone lines can only transfer analog data. If a computer is to be connected to internet through telephone, then it must convert digital data to analog data before transmitting the computer signals.
(2) Converting one signal form to antoher form is called modulation and reconverting it to original form is called as demodulation.
(3) Modem is modulator/demoduator. Modem is used to connect computer to internet. Modems convert digital data to analog data and vice-a-versa.
(4) They have two advantages:
      (a) Modem allows higher speed of transmission on any given analog line.
      (b) Modem reduce effect of noise and distortion.
(5) The function of modem is described by following figure.

(6) Modems are classified into two categories according to transmission method.
      (a) Asynchronous modems.
      (b) Synchronous modems
 (a) Asynchronous modems
      (i) In asynchronous modems, transmission dock is not used for synchronisation. Instead it uses, bit synchronisation.
      (ii) Here each frame begins with a start bit that enables the receiving device to adjust to the timing of transmitted signal.
      (iii) Messages are kept short.
      (iv) It is used to transmit character data.
      (v) Asynchronous transmission is simple, inexpensive technology. It is used for PC to PC communication.
 (b) Synchronous modems
      (i) Synchronous modes uses clocks on transmitting and receiving devices

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 2015-2016 (March) (with solutions)
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 2016-2017 (March) (with solutions)
Question 3.1.3 | 3.00 marks
Solution Write a short note on MODEM. Concept: Networking Technology.
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