Higher order spectral estimation techniques have been applied to the backscattered signals received from the troposphere and lower stratosphere by the Gadanki mesosphere-stratosphere-troposphere (MST) radar. These techniques allow identification of signals that have non-Gaussian probability distribution. To understand these processes and their effect on estimation of the atmospheric parameters, power spectrum, and bispectrum analyses have been performed on the signals received in both vertical and off-vertical directions. The results show that the backscattered echoes received in the vertical direction are significantly non-Gaussian, while those received in the off-vertical direction are inferred to have predominant Gaussian component. It is demonstrated that the bispectral analysis technique has capability for estimating the vertical wind component with greater accuracy than that derived from the commonly employed fast Fourier transform based power spectral technique.