Spectrum manipulation for improved resolution

A novel approach to improving the frequency resolution of parametric power spectrum estimation for signals with rational spectra is discussed. Specifically, the effect of errors in the calculated autocorrelation values is considered. Analysis and numerical simulation reveal that the error sensitivity becomes acute when the poles are closely spaced, demonstrating one of the difficulties encountered when high-resolution spectrum estimates are required. To remedy this problem, two modified spectrum-estimation procedures are proposed. The first applies to situations where discrete-time techniques are used to estimate the spectra of continuous-time processes. It involves selecting the autocorrelation function sampling period to separate the poles. The second procedure involves desampling an autocorrelation sequence to separate closely spaced poles artificially. Numerical examples verify improved resolution for both procedures