Pulse Amplitude Modulation (PAM):
- In PAM, the amplitude of the carrier signal is varied in proportion to the digital data being transmitted. The amplitude levels represent the different binary values (0s and 1s).
- PAM uses multiple amplitude levels to represent binary information. Each amplitude level corresponds to a specific bit pattern.
- The receiver measures the amplitude of the received signal and decodes the corresponding binary data.
Pulse Width Modulation (PWM):
- In PWM, the width (duration) of the carrier signal pulses is varied in proportion to the digital data being transmitted. Longer pulses represent 1s, while shorter pulses represent 0s.
- PWM utilizes the varying pulse widths to encode binary information. The width of each pulse determines the bit value: a longer pulse represents a 1, and a shorter pulse represents a 0.
- The receiver measures the width of the received pulses and decodes the corresponding binary data.
Comparison:
- Both PAM and PWM are modulation techniques used in digital communication to transmit binary data.
- In PAM, the information is encoded in the amplitude of the pulses, while in PWM, the information is encoded in the width (duration) of the pulses.
- PAM requires multiple amplitude levels for representation, while PWM uses pulse widths for representation.
- PWM is more commonly used in applications where power efficiency is important, such as controlling the speed of motors or the brightness of LEDs. This is because it can provide variable voltage output while controlling power dissipation more efficiently.
- PAM, on the other hand, is commonly used in analog communication where a continuous range of amplitudes is needed, such as in audio or video signals.
These modulation techniques allow for the efficient transmission of digital data by converting it into analog signals suitable for different transmission media, such as copper wires or wireless channels.