The discrete polynomial transform (DPT) has been introduced recently a
s a computationally efficient algorithm for estimating the phase param
eters of constant-amplitude polynomial phase signals. In this correspo
ndence, we present a modification of the DPT, which improves the estim
ation accuracy. We show by a perturbation analysis that the mean-squar
ed error of the estimates is reduced when the order of the polynomial
is three or greater.