Raised-cosine filter
The raised-cosine filter is a filter frequently used for pulse-shaping in digital modulation due to its ability to minimise intersymbol interference (ISI). Its name stems from the fact that the non-zero portion of the frequency spectrum of its simplest form ( β = 1 {\displaystyle \beta =1} ) is a cosine function, 'raised' up to sit above the f {\displaystyle f} (horizontal) axis.