This tool calculates the **modulation index**, which quantifies how much a carrier wave is modulated by the input signal in either **AM** (Amplitude Modulation) or **FM** (Frequency Modulation).

Amplitude Modulation (AM)

The modulation index $m$ is given by: $$m=\frac{A_m}{A_c}$$ Where $A_m$ is the peak amplitude of the modulating signal and $A_c$ is the carrier amplitude.

• m < 1: Undermodulated
• m = 1: 100% modulation (ideal)
• m > 1: Overmodulated — distortion likely

Frequency Modulation (FM)

The FM modulation index $\beta$ is: $$\beta =\frac{\mathrm{\Delta }f}{f_m}$$ Where:

• $\mathrm{\Delta }f$: Frequency deviation (Hz)
• $f_m$: Modulating frequency (Hz)

A higher index means more bandwidth. Narrowband FM (β < 1), wideband FM (β > 1).

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