Question

A pre-emphasis circuit provides extra noise-immunity by________.

• A. Boosting the bass frequencies
• B. Amplifying the higher audio frequencies
• C. Pre-amplifying the whole audio band
• D. Converting PM to FM

Hint:

Pre-emphasis boosts high-frequency components before FM modulation to improve SNR against noise.

Answer 1

The Correct Option is B

Pre-emphasis is a technique used in FM transmission to combat high-frequency noise. The idea is simple:
- Noise tends to affect higher frequencies more than lower ones.
- So, the high-frequency components of the message signal are amplified before transmission (this is "pre-emphasis").
- At the receiver side, a de-emphasis filter attenuates the high frequencies proportionally, thereby restoring the original signal and reducing high-frequency noise.
This technique improves signal-to-noise ratio (SNR) for high frequencies, making FM more robust.