Improved instantaneous frequency estimation using an adaptive short-time Fourier transform

Instantaneous frequency estimation (IFE) arises in a variety of important a pplications, including FM demodulation. We present here a new time-frequenc y representation (TFR)-based approach to IFE based on an:adaptive short-tim e Fourier transform (ASTFT). This TFR leads naturally to a type of short-te rm ML estimator of the IE To further improve the performance, we apply a mu ltistate hidden Markov model (HMM)-based post-estimation tracker. The end r esult is up to a 16-dB reduction in the threshold SNR over the frequency di scriminator (FD) and an 8-dB improvement over phase-locked loop (PLL) for a Rayleigh fading channel.