Adaptive time-varying spectral analysis for multiple narrowband signals

An adaptive technique to compute the Fourier coefficients of a time-varying spectrum is presented. The algorithm performs a least squares decomposition of the signal onto a nonharmonic Fourier basis. The algorithm updates the spectral estimate on a sample by sample basis in the time domain. This technique produces a signal decomposition with very good localization in both time and frequency domains. The detection of tones spaced closer than expected by the uncertainty principle (super-resolution) is shown by computer simulation. Computational complexity issues of the new method are also discussed.<>