The main difference between AM and FM radio waves lies in how the sound signal is encoded onto the carrier wave.
1. Amplitude Modulation (AM):
- In AM, the amplitude (strength) of the radio wave is varied to carry the sound information.
- The frequency of the wave remains constant.
- AM is more affected by noise and interference because noise typically affects amplitude.
- It uses lower frequencies (typically 535 to 1605 kHz), allowing it to travel longer distances, especially at night.
- AM radio has lower sound quality compared to FM.
2. Frequency Modulation (FM):
- In FM, the frequency of the radio wave is varied to transmit sound.
- The amplitude remains constant.
- FM is less affected by noise, making it clearer and more stable.
- It uses higher frequencies (usually 88 to 108 MHz), which limits its range but improves sound quality.
- FM radio offers better audio fidelity, especially for music.