HIGH-RESOLUTION FREQUENCY-WAVENUMBER SPECTRA

The method of high-resolution spectral analysis has been applied to one- and two-dimensional wavenumber spectra. In this method a prediction operator is used to extend the length of the spatial correlation functions in order to obtain higher resolution of the resulting spectra in wavenumber space. It is most useful in the case of small arrays, where the spatial correlation functions are too short to give adequate resolution for the ordinary frequency- wavenumber spectra. A theoretical description of the method, its procedures, and its relation to ordinary wavenumber spectra is given. In particular, an analytical expression is derived for the resolution and the response of the process in the case of an input plane wave, where the high-resolution method is averaged over all reference sensors. Disadvantages of the high-resolution method are discussed, in particular an unrecoverable distortion of the true amplitude spectrum.