This document discusses different types of analog-to-analog modulation techniques used in analog transmission including amplitude modulation, frequency modulation, and phase modulation. Amplitude modulation varies the amplitude of the carrier signal based on the modulating signal. Frequency modulation varies the frequency of the carrier signal based on the modulating signal. Phase modulation only changes the phase of the carrier signal which manifests as a frequency change. The document provides equations to calculate the bandwidth requirements for each modulation technique based on the bandwidth of the modulating signal.