ESTIMATING AND INTERPRETING THE INSTANTANEOUS FREQUENCY OF A SIGNAL .2. ALGORITHMS AND APPLICATIONS

This paper, which addresses the important issue of estimating the instantaneous frequency (IF) of a signal, is a sequel to the paper which appears in this issue, and dealt with the concepts relating to the IF. In this paper the concept of IF is extended to be able to cope with discrete time signals. The specific problem explored is that of estimating the IF of frequency modulated (FM) discrete-time signals imbedded in Gaussian noise. There are many well established methods for estimating the IF-these methods include differentiation of the phase and smoothing thereof, adaptive frequency estimation techniques such as the phase locked loop (PLL), and extraction of the peak from time-varying spectral representations. More recently methods based on a modeling of the signal phase as a polynomial have been introduced. All of these methods are reviewed, and their performances are compared on both simulated and real data. Guidelines are given as to which estimation method should be used for a given signal class and signal-to-noise ratio (SNR).