Module to sharpen FIR filters
Reference: Hamming, Sect 6.6
H'(z) = 3 * H(z)^2 - s * H(z)^3 = H(z)^2 * (3 - 2 * H(z))
Procedure:
Filter the signal once with H(z)
Double this
Subtract this from 3x
Filter this twice by H(z) or once by H(z)^2