Question

Explain the concept of modulation and its need in long distance communication. What is difference
between amplitude modulation and frequency modulation?

Answer 1

Answer on Question #53682-Physics-Optics

Explain the concept of modulation and its need in long distance communication. What is difference between amplitude modulation and frequency modulation?

Answer

When audio signals are transmitted over thousands of kilometers through radio transmission, the audio frequencies that lie within the frequency range of 15 Hertz to 20 Kilohertz have very small signal power and thus cannot be transmitted via antenna for communication purposes. The radiation of electrical energy is only possible at frequencies above 20 Kilohertz. The main advantage of high frequency signals is that they can be transmitted over very long distances by dissipating very small power. Thus, the audio signals must be sent along with the high frequency signals for communication. This can be done by superimposing electrical audio signals on a high frequency wave called the carrier wave. The carrier wave is generated from radio-frequency oscillators and is undamped in nature. Thus, when the audio-frequency signal is superimposed on a carrier wave, the resulting wave gets all the characteristics of the audio signal. The method of superimposing an audio signal over the carrier wave is called **modulation**.

After modulation is done, the resulting wave can be given to the antenna and the signal can be transmitted over a long distance.

Comparison chart (difference between amplitude modulation and frequency modulation)

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