Define the following as related to communication system: Modulation Phase modulation Percent modulation Modulation index

Modulation: The process of varying a carrier wave's characteristics (amplitude, frequency, or phase) in accordance with the information signal to be transmitted.

Phase Modulation (PM): A type of modulation where the phase of the carrier wave is varied in proportion to the amplitude of the information signal.

Percent Modulation:
- For Amplitude Modulation (AM): The ratio of the maximum amplitude change of the carrier wave to its unmodulated amplitude.
- For PM: The ratio of the maximum phase deviation of the carrier wave to the unmodulated phase angle.

Modulation Index (m): A dimensionless parameter that quantifies the degree of modulation.
- For AM: m = ΔA / A, where ΔA is the amplitude change and A is the unmodulated amplitude.
- For PM: m = Δφ / Φ, where Δφ is the phase deviation and Φ is the unmodulated phase angle.