Modulatsiooninäitaja

Modulatsiooninäitaja, often translated as modulation index or modulation depth, is a dimensionless quantity used to describe the extent of variation in a signal that is being modulated. In amplitude modulation (AM), it quantifies the ratio of the amplitude of the modulating signal to the amplitude of the carrier wave. A modulation index of 1 (or 100%) signifies that the carrier wave's amplitude varies from zero to twice its original amplitude. Exceeding a modulation index of 1 in AM leads to overmodulation, where the carrier signal is completely suppressed for portions of the modulating cycle, resulting in distortion and inefficient transmission.

In frequency modulation (FM), the modulation index is defined as the ratio of the frequency deviation to the frequency of the modulating signal. A higher modulation index in FM means a wider range of frequencies is occupied by the modulated signal. The concept of modulation index is crucial for understanding the characteristics of modulated signals, including bandwidth requirements, signal-to-noise ratio, and the potential for distortion. It provides a standardized way to compare the degree of modulation across different signals and modulation schemes.