With the aid of illustration explain the difference between pulse amplitude modulation (PAM) and pulse width modulation (PWM)

Pulse Amplitude Modulation (PAM)

- Modulates the amplitude of a rectangular pulse signal.
- The amplitude of the pulses varies in proportion to the amplitude of the input signal.
- More amplitude levels can provide higher precision, but also result in a wider signal bandwidth.

Pulse Width Modulation (PWM)

- Modulates the width of a rectangular pulse signal.
- The duration of the pulses varies in proportion to the amplitude of the input signal.
- The repetition rate (frequency) of the pulses remains constant.
- PWM is often used in power electronics and control systems due to its efficiency and low noise.

Comparison:

| Feature | PAM | PWM |
|---|---|---|
| Amplitude variation | Yes | No |
| Pulse width variation | No | Yes |
| Bandwidth | Wider for higher precision | Narrower |
| Efficiency | Lower | Higher |
| Noise | Higher | Lower |
| Applications | Audio and data transmission | Power electronics, control systems |

Illustration:

[Image of PAM and PWM signals]

PAM:

- The input signal is a sine wave.
- The PAM signal has rectangular pulses with varying amplitudes that follow the sine wave.

PWM:

- The input signal is a square wave.
- The PWM signal has rectangular pulses with constant amplitude, but varying widths that follow the square wave.