What are the types of modulations

Analog Modulation: In analog modulation, a continuous analog message signal is used to vary a characteristic of a continuous analog carrier wave.

• Amplitude Modulation (AM): The amplitude of the carrier wave is varied in proportion to the instantaneous amplitude of the modulating signal.
• Frequency Modulation (FM): The frequency of the carrier wave is varied in proportion to the instantaneous amplitude of the modulating signal.
• Phase Modulation (PM): The phase of the carrier wave is varied in proportion to the instantaneous amplitude of the modulating signal.

Digital Modulation: In digital modulation, a digital bit stream (discrete message signal) is used to vary a characteristic of an analog carrier wave.

• Amplitude Shift Keying (ASK): The amplitude of the carrier wave is varied to represent binary data (e.g., one amplitude for '0' and another for '1').
• Frequency Shift Keying (FSK): The frequency of the carrier wave is varied to represent binary data (e.g., one frequency for '0' and another for '1').
• Phase Shift Keying (PSK): The phase of the carrier wave is varied to represent binary data (e.g., different phase shifts for '0' and '1').
• Pulse Code Modulation (PCM): An analog signal is sampled, quantized, and then encoded into a digital bit stream.