  In this paper, we propose a new method to estimate instantaneous frequency
using a combined approach based on the discrete linear chirp transform (DLCT)
and the Wigner distribution (WD). The DLCT locally represents a signal as a
superposition of linear chirps while the WD provides maximum energy
concentration along the instantaneous frequency in the time-frequency domain
for each of the chirps. The developed approach takes advantage of the
separation of the linear chirps given by the DLCT, and that for each of them,
the WD provides an ideal representation. Combining the WD of the linear chirp
components, we obtain a time-frequency representation free of cross-terms that
clearly displays the instantaneous frequency. Applying this procedure locally,
we obtain an instantaneous frequency estimate of a non-stationary
multicomponent signal. The proposed method is illustrated by simulation. The
results indicate the method is efficient for the instantaneous frequency
estimation of multicomponent signals embedded in noise, even in cases of low
signal to noise ratio.
