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Modulation and Demodulation-1 Study Notes for Electronics and Communication

By BYJU'S Exam Prep

Updated on: September 25th, 2023

In this article, Candidates can find study notes on Modulation and Demodulation-I consists of topics such as Introduction to Communication, Amplitude Modulation and Demodulation, Voltage, Current and Frequency Relations.

In this article, Candidates can find study notes on Modulation and Demodulation-I consists of topics such as Introduction to Communication, Amplitude Modulation and Demodulation, Voltage, Current and Frequency Relations.

1. COMMUNICATION

  • Communication is a process by which information is exchanged between individuals through a common system of symbols
  • It is a technique for expressing ideas effectively
  • It is a system of routes for moving troops, supplies, and vehicles
  • Communication is the transfer of information from one point in space and time to another point.

Block diagram of a communication system:

1

  • Transmitter: couples the message onto the channel using high-frequency signals
  • Receiver:  restores the signal to its original form
  • Channel: the medium used for transmission of signals
  • Modulation: the process of shifting the frequency spectrum of a message signal to a frequency range in which more efficient transmission can be achieved
  • Demodulation: the process of shifting the frequency spectrum back to the original baseband frequency range and reconstructing the original form, if necessary

 

2. Modulation:

  • Modulation may be defined as the process by which some characteristics of a signal called carrier is varied in accordance with the instantaneous value of another signal called modulating the signal.
  • The carrier frequency is greater than the modulating frequency. The signal resulting from the process of modulation is called the modulating signal.
  • Types of Modulation: When the carrier wave is continuous in nature, the modulation process is known as Continuous Wave (CW) modulation or analog modulation. 
    1. Amplitude Modulation
    2. Angle Modulation

Amplitude Modulation:

  • A system of modulation in which the envelope of the transmitted wave contains a component similar to the waveform of the signal to be transmitted.
  • The envelope of the modulated carrier has the same shape as the message waveform, achieved by adding the translated message that is appropriately proportional to the unmodulated carrier.
  • Amplitude modulation may be defined as a system in which the maximum amplitude of the carrier wave is made proportional to the instantaneous value (amplitude) of the modulating or baseband signal.
  • Let c(t) = Vc cos ωct, and m(t) = Vm sin ωmt. Then the amplitude modulated signal is

Modulation and Demodulation-1 Study Notes for Electronics and Communication

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