The main difference between AM (Amplitude Modulation) and FM (Frequency Modulation) lies in how they encode and transmit audio signals:
AM: In AM radio, the strength or amplitude of the carrier wave is varied in proportion to the waveform of the audio signal. This means that the amplitude of the radio wave changes to encode the sound information.
FM: In FM radio, the frequency of the carrier wave is varied according to the waveform of the audio signal. Instead of changing the amplitude, FM alters the frequency of the radio wave to encode sound information.
AM: AM signals are more susceptible to interference from atmospheric conditions, electrical appliances, and other radio stations. This can lead to static, noise, and distortion in the audio.
FM: FM signals are less susceptible to interference and noise compared to AM signals. This results in clearer audio quality, making FM preferable for music and high-fidelity audio transmission.
Bandwidth and Coverage
AM: AM signals have a wider bandwidth and can cover longer distances with less power. They are often used for broadcasting over long distances, especially at night when atmospheric conditions enhance their propagation.
FM: FM signals have a narrower bandwidth but provide better sound quality and are less affected by noise. They are commonly used for local radio stations due to their limited range.
AM: The modulation technique in AM involves varying the amplitude of the carrier wave. The audio signal is encoded by changing the height (amplitude) of the carrier wave.
FM: FM modulation involves varying the frequency of the carrier wave. The audio signal is encoded by changing the rate at which the carrier wave oscillates.
In summary, while both AM and FM are methods of transmitting radio signals, they differ in their modulation techniques, signal quality, susceptibility to interference, and coverage capabilities. FM signals generally offer better sound quality and are less prone to interference, making them suitable for music and high-fidelity audio transmission, while AM signals are better suited for long-distance broadcasting.