A Zoom Algorithm for Spectral Correlation Density Estimation

A new spectral correlation density (SCD) estimator is proposed. It exploits the chirp zeta transform algorithm in a modified version of the strip spectral correlation analyzer (SSCA) and is referred to as zoom SSCA. It provides an estimate of the SCD in the desired cycle- and spectral-frequency rectangular region without computing the SCD in the whole domain. The cycle- and spectral-frequency analysis intervals can be independently selected and the cycle- and spectralfrequency resolution is constant in the whole analysis region. As an example of application, the cyclic spectral analysis of a covert weak communication signal in the presence of strong noise and interference is carried out.