Question

____ is used to reduce inter-symbol interference.

(a) Root raised cosine filter

(b) Sinc filter

(c) Root raised sinc filter

(d) Cosine filter

I had been asked this question in a national level competition.

This intriguing question comes from Techniques in section Cognitive Techniques of Cognitive Radio

Answer 1

Right answer is (a) Root raised cosine filter

To elaborate: The raised cosine filter is an implementation of Nyquist low pass filter. It is used for pulse shaping and to minimise inter-symbol interference. It derives its name from the frequency spectrum which resembles a cosine function.