Question

State the reasons why a square root raised cosine filter is used at the transmitter and another square root raised cosine filter is used as a matched filter as the receiver.

Answer 1

square root raised cosine filter is frequenctly used filter as transmitter of digital communication and also as matched filter at receiver. We use this because to reduce the effect of intersymbol interference.Intersymbol interference is a signal or distortion occurs because of interference of one symbol with other symbols. And this interference makes the communication unreliable.

And by using two square root raise cosine filters at transmitter and receiver gives the output as raised cosine filter. we can check this easily with frequency response of system.

And the overall raised cosine filter characterstics will help us to make the system satisfies the nyquist criterion.

Nyquist criteria is related to bandwidth limitations. where the overall bandwidth of channel should be 2 times of maximum frequency component of input.

So the main reasons are

> To make communication more reliable

>To decrese the intersymbol interference

>To satisty the basic communication channel bandwidth related nyquist criteria.