Pre-emphasis in FM system is done to

Options

A. compress modulating signal
B. expand modulating signal
C. amplify lower frequency component of the modulating signal
D. amplify higher frequency component of the modulating signal

Explanation

**Step-by-step Solution:**

1. **Understanding Pre-emphasis in FM Systems:**
Pre-emphasis in Frequency Modulation (FM) systems is a technique used to improve the signal-to-noise ratio for higher frequency components of the modulating signal.

2. **Identifying the Purpose of Pre-emphasis:**
The main purpose of pre-emphasis is to amplify the higher frequency components of the modulating signal before transmission. This is essential because higher frequency signals are more susceptible to noise and attenuation during transmission.

3. **Analyzing the Options:**
- **Option a: Compress modulating signal** - This is incorrect because pre-emphasis does not compress the signal; it modifies the amplitude of certain frequencies.
- **Option b: Expand modulating signal** - This is also incorrect as pre-emphasis does not expand the signal in a general sense.
- **Option c: Amplify lower frequency component of the modulating signal** - This is incorrect because the focus of pre-emphasis is on the higher frequency components, not the lower ones.
- **Option d: Amplify higher frequency component of the modulating signal** - This is the correct option as it aligns with the purpose of pre-emphasis.

4. **Conclusion:**
Therefore, the correct answer is **d. Amplify higher frequency component of the modulating signal**. This amplification helps in reducing the effects of noise and attenuation that higher frequency signals experience during transmission.

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