Time-varying spectral estimation using the instantaneous power spectrum (IPS)

The spectral content of time-varying signals is examined using a modified version of the instantaneous power spectrum (IPS). The short duration periodogram and the pseudo Wigner-Ville distribution (PWD) have been used extensively to display the time-varying spectral information. A disadvantage of the periodogram is its inherently poor resolution, due to the requirement of matching the resolution width to the spectral dynamics of the signal. Potential problems associated with PWD are spectral cross terms and an inability to resolve spectral components at the endpoints of the analysis segment. A modified version of IPS is shown to be less sensitive to these types of problems. In addition, IPS can work with real-valued signals sampled at the traditional Nyquist rate