Low SNR approximation to phase PDF for PSK signals

For the original article see ibid., vol. 30, no. 16, p. 1279-80 (1994). In the afore-mentioned paper the authors, P.C. Sapiano et al., derived a Fourier series expansion of the probability density function of the signal phase in the presence of AWGN. The commenter shows how Fourier series coefficients may be obtained directly from this expansion. In reply, the authors agree with this but maintain that their alternative route for deriving the Fourier series coefficients, based on series expansions of special functions, is still valid. However, they consider that this does not detract from the main thrust of their argument which was based on the low SNR approximation of a multilevel PSK phase PDF and an efficient method for generating the Fourier series coefficients