Variable linear phase digital filters

Graduation date: 1984Linear phase variable filters that are obtained with a frequency transformation of the form cos(ω) = P(cos(W)) were analyzed, where P is a finite degree polynomial, ω is the prototype frequency and W is the transformed filter frequency. A new transformation of third order is proposed. The new variable filter is not as efficient as first and second order transformations, but has a wider range of variation that allows continuous variation of the cutoff frequency over about 60% of the frequency range