On development of Hilbert-Huang Transform data processing real-time system with 2D capabilities

Unlike other digital signal processing techniques such as the Fast Fourier Transform for one-dimensional (1D) and two-dimensional (2D) data (FFT1 and FFT2) that assume signal linearity and stationarity, the Hilbert-Huang Transform (HHT) utilizes relationships between arbitrary signal's local extrema to find the signal instantaneous spectral representation. This is done in two steps. Firstly, the Huang Empirical Mode Decomposition (EMD) is separating input signal of one variable s(t) into a finite set of narrow-band Intrinsic Mode Functions {IMF1(t), IMF2(t)... IMFk(t)} that add up to the signal s(t). The IMFs comprise the signal adaptive basis that is derived from the signal, as opposed to artificial basis imposed by the FFT or other heritage frequency analysis methods. Secondly, the HHT is applying the Hilbert Transform to each IMFi(t) signal constituents to obtain the corresponding analytical signal Si(t). From the analytical signal the HHT generates the Hilbert-Huang Spectrum. Namely, a single instantaneous frequency ωi(t) for signal Si(t) at each argument t is obtained for each of the k-Huang IMFs. This yields the Hilbert-Huang spectrum {ω(IMF1(t)), ω(IMF2(t))... ω(IMFk(t))} at each domain argument t for s(t) that was not obtainable otherwise. The HHT and its engineering implementation - the HHT Data Processing System (HHT-DPS) for 1D was developed at the NASA Goddard Space Flight Center (GSFC). The HHT-DPS is the reference system now used around the world. However, the state-of-the-art HHT-DPS works only for 1D data, as designed, and it is not a real-time system. This paper describes the development of the reference HHT Data Processing Real-Time System (HHTPS-RT) with 2D capabilities or HHT2 to process large images as the development goal. This paper describes the methodology of research and development of the new reference HHT2 Empirical Mode Decomposition for 2D (EMD2) system and its algorithms that require high capability computing. It provides this system prototype test results and also introduces the HHT2 spectrum concepts. It concludes with suggested areas for future research.