A computer implemented physical signal analysis method includes four basic
steps and the associated presentation techniques of the results. The first
step is a computer implemented Empirical Mode Decomposition that extracts
a collection of Intrinsic Mode Functions (IMF) from nonlinear,
nonstationary physical signals. The decomposition is based on the direct
extraction of the energy associated with various intrinsic time scales in
the physical signal. Expressed in the IMF's, they have well-behaved
Hilbert Transforms from which instantaneous frequencies can be calculated.
The second step is the Hilbert Transform which produces a Hilbert
Spectrum. Thus, the invention can localize any event on the time as well
as the frequency axis. The decomposition can also be viewed as an
expansion of the data in terms of the IMF's. Then, these IMF's, based on
and derived from the data, can serve as the basis of that expansion. The
local energy and the instantaneous frequency derived from the IMF's
through the Hilbert transform give a full energy-frequency-time
distribution of the data which is designated as the Hilbert Spectrum. The
third step filters the physical signal by combining a subset of the IMFs.
In the fourth step, a curve may be fitted to the filtered signal which may
not have been possible with the original, unfiltered signal.
