Relationships involving third moments and bispectra of a harmonic process

Relationships between third moments of a harmonic random process and its bispectrum are presented. The skewness and asymmetry (with respect to a vertical axis) of the process and its derivative can be obtained by integrating the real, imaginary, and frequency-scaled real and imaginary parts of the bispectrum, respectively. Triads of Fourier coefficients containing a high-frequency component can contribute substantially to the third moments of the derivative of the process.