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Convert FIR Type I lowpass to FIR Type 1 lowpass with inverse bandwidth


g = firlp2lp(b)


g = firlp2lp(b) transforms the Type I lowpass FIR filter b with zero-phase response Hr(w) to a Type I lowpass FIR filter g with zero-phase response [1 - Hr(π-w)].

When b is a narrowband filter, g will be a wideband filter and vice versa. The passband and stopband ripples of g will be equal to the stopband and passband ripples of b.


Overlay the original narrowband lowpass and the resulting wideband lowpass

b = firgr(36,[0 .2 .25 1],[1 1 0 0],[1 5]);
hold on
h = firlp2lp(b);


Saramaki, T, Finite Impulse Response Filter Design, Handbook for Digital Signal Processing. S.K. Mitra and J.F. Kaiser Eds. Wiley-Interscience, N.Y., 1993, Chapter 4.

See Also


Introduced in R2011a

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