undermodulation

Undermodulation is a phenomenon that occurs in analog communication systems, particularly in amplitude modulation (AM) and frequency modulation (FM) systems. It refers to the condition where the modulation index is less than 1, meaning the modulation depth is not sufficient to fully utilize the available modulation range. In AM systems, undermodulation results in a distorted waveform, where the carrier amplitude does not reach its maximum or minimum limits. This can lead to a reduction in the signal's dynamic range and an increase in distortion, making the audio signal less clear and more susceptible to noise. In FM systems, undermodulation can cause a reduction in the signal's bandwidth and an increase in the noise floor, resulting in a less clear and more distorted audio signal. To avoid undermodulation, the modulation index should be carefully adjusted to ensure that the modulation depth is sufficient to fully utilize the available modulation range. This can be achieved by adjusting the modulation index or the modulation depth, depending on the specific system and application.