Through extracting the local mean value curve of nonlinear and non-stationary data

any complicated data set can be adaptively decomposed into a finite number of Intrinsic Mode Functions (IMFs) which have physical meaning and can be expressed in a kind of joint energy-frequency-time distribution form by the HHT (Hilbert-Huang Transform)

a typical realization of the Local Wave Analysis (LWA)

so a meaningful instantaneous frequency can be obtained.The method has some good features compared to the other methods

such as having better joint time-frequency resolution than Wavelet analysis

and without cross terms that exist in Wigner-Ville distribution analysis.Therefore

it is especially powerful for analysis of non-stationary and nonlinear signals.In this paper

the mathematic expressions of IMFs and the limit of frequency resolution of the HHT are discussed further

and a new principle and method of adaptive frequency multiresolution analysis is put forward for developing the theory of the LWA.