Root-raised-cosine filter

This helps in constraining the occupied bandwidth of the waveform without introducing intersymbol interference (ISI).

: or: To have minimum ISI (Intersymbol interference), the overall response of transmit filter, channel response and receive filter has to satisfy Nyquist ISI criterion.

The RRC filter is characterised by two values; β, the roll-off factor, and Ts the reciprocal of the symbol-rate.

The impulse response of such a filter can be given as[citation needed]: though there are other forms as well.

Unlike the raised-cosine filter, the impulse response is not zero at the intervals of ±Ts.

The impulse response of a root-raised cosine filter multiplied by T s , for three values of β : 1.0 (blue), 0.5 (red) and 0 (green).