Define depth of modulation as applied to a modulated wave.

Depth of modulation refers to the ratio of the amplitude of the modulating signal to the amplitude of the carrier signal in a modulated wave. It is a measure of how much the amplitude of the carrier signal is varied by the modulating signal. A higher depth of modulation indicates a greater variation in the amplitude of the carrier signal, resulting in a more pronounced modulation effect.

Depth of Modulation

In a modulated wave, the depth of modulation is a measure of the degree to which the carrier wave's amplitude, frequency, or phase is varied by the modulating signal.

Mathematical Definition:

For a carrier wave of amplitude A and modulating wave of amplitude m, the depth of modulation (D) is defined as:

```
D = (m / A) x 100%
```

Types of Depth of Modulation:

- Amplitude Modulation (AM): Variation of carrier amplitude by the modulating signal.
- Frequency Modulation (FM): Variation of carrier frequency by the modulating signal.
- Phase Modulation (PM): Variation of carrier phase by the modulating signal.

Values of Depth of Modulation:

- 0% Depth of Modulation: No modulation, carrier wave is unchanged.
- 100% Depth of Modulation: Maximum possible variation in carrier wave.
- Overmodulation: Depth of modulation exceeding 100%, resulting in distortion of the modulated wave.

Significance of Depth of Modulation:

- Determines the amount of information encoded in the modulated wave.
- Affects the signal-to-noise ratio (SNR) of the modulated wave.
- Controls the bandwidth required for transmission.
- Higher depth of modulation typically leads to higher SNR and wider bandwidth.