AM, FM and Signal Modulation

Source- This post on AM, FM and Signal Modulation is based on the article “AM, FM and Signal Modulation” published in Indian Express on 16th September 2024.

Why in News?

AM (Amplitude Modulation) and FM (Frequency Modulation) are two fundamental techniques used in electronic communication to transmit information over radio waves.

What is Amplitude Modulation (AM)?

In AM, the amplitude of the carrier wave is varied in accordance with the information signal being transmitted. This means that as the amplitude of the input signal changes, the amplitude of the carrier wave also changes proportionally. The frequency and phase of the carrier wave remain constant during this process.

AM is typically used for broadcasting over long distances due to its ability to travel further. However, it is more susceptible to noise and interference, which can degrade sound quality.

Key Characteristics of AM-

Carrier Wave- Amplitude varies; frequency and phase remain constant.
Sound Quality- Generally lower than FM; more susceptible to static and noise.
Frequency Range- Typically operates between 535 to 1705 kHz.
Distance- Can cover larger distances due to lower frequencies.

What is Frequency Modulation (FM)?

FM involves varying the frequency of the carrier wave according to the information signal. In this method, while the amplitude remains constant, the frequency changes in relation to the amplitude of the input signal.

This technique allows FM signals to provide better sound quality and greater resistance to noise compared to AM signals. FM is widely used for music and voice broadcasting because it can transmit a wider bandwidth of audio signals.

Key Characteristics of FM-

Carrier Wave- Frequency varies; amplitude and phase remain constant.
Sound Quality- Higher than AM; less susceptible to noise.
Frequency Range- Typically operates between 88 to 108 MHz.
Distance- Generally covers shorter distances than AM but offers superior sound fidelity.

What is Signal Modulation?

Signal modulation is a technique used in telecommunications where a carrier wave’s characteristics– such as amplitude, frequency, or phase– are altered in accordance with a modulating signal (the information being sent). This modulation allows for effective transmission of audio, video, or data signals over various media.

Types of Modulation

Amplitude Modulation (AM): Varies amplitude.
Frequency Modulation (FM): Varies frequency.
Phase Modulation (PM): Varies phase; often used in conjunction with FM.

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