Which of the following modulation index produces noise?

Options

A. 0.5
B. 0.8
C. 1.2
D. 0.7

Answer

To determine which modulation index produces noise, we first need to understand the concept of modulation index in communication systems.

### Step-by-Step Solution:

1. **Understanding Modulation Index**:
- The modulation index (m) is defined as the ratio of the amplitude of the modulating signal (A_m) to the amplitude of the carrier signal (A_c).
- Mathematically, it is expressed as:
\[ m = \frac{A_m}{A_c} \]

2. **Types of Modulation**:
- There are various types of modulation such as Amplitude Modulation (AM), Frequency Modulation (FM), and Phase Modulation (PM).
- Each type of modulation has its own characteristics and behavior in the presence of noise.

3. **Noise in Communication Systems**:
- Noise refers to any unwanted signal that interferes with the transmission and reception of the desired signal.
- Different modulation schemes have different levels of susceptibility to noise.

4. **Effect of Modulation Index on Noise**:
- In Amplitude Modulation (AM), a higher modulation index can lead to distortion and increased susceptibility to noise.
- In Frequency Modulation (FM), the modulation index can also affect the noise performance, but FM is generally more resistant to noise compared to AM.

5. **Conclusion**:
- A modulation index that is too high in AM can produce noise due to over-modulation, leading to distortion.
- Therefore, it can be concluded that a higher modulation index in AM is more likely to produce noise.

### Final Answer:
The modulation index that produces noise is typically a higher modulation index in Amplitude Modulation (AM).

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