Question

What is the use of pre-emphasis?

(a) to increase the signal to noise ratio for higher audio frequencies

(b) to allow stereo audio to be carried by FM stations

(c) to increase the signal to noise ratio for all audio frequencies

(d) to increase the signal to noise ratio for lower audio frequencies

I had been asked this question in class test.

This question is from Non Linear Device in section Side Band Techniques of Analog Communications

Answer 1

The correct choice is (d) to increase the signal to noise ratio for lower audio frequencies

The best I can explain: Pre-emphasis is applied in communication systems to improve signal strength before transmission. It refers to boosting the amplitudes of the weak modulating voltages for high audio frequencies. It is also helpful in increasing S/N ratio but for lower audio frequencies only.