Research On The Implementation Technologies Of EMD Method Based On DSP

The implementation technology of HMD method based on DSP is researched in this paper.Traditional non-stationary data processing methods have some disadvantages. Short-time Fourier transform relies on the traditional Fourier spectral analysis, so it is limited to the assumption of the data to be piecewise stationary. The shortcoming of Wigner-Ville is the severe cross terms as indicated by the existence of negative power for some frequency ranges. So far one of the best available methods to process non-stationary data is wavelet analysis. However it has many problems. Empirical Mode Decomposition method (EMD) is a new method for analysing nonlinear and non-stationary data, with which any complicated data set can be decomposed into a finite and often small number of Intrinsic Mode Functions (IMF) that admit well-behaved Hilbert transforms. Thus the energy-frequency-time distribution of the signal is constructed. This method developed by Huang et al is implemented through HHT (Hilbert-Huang Transform) toolbox.Because domestic and oversea research on EMD method at present is mainly focused on software, implementation of EMD method based on DSP and PCI is discussed in the paper. It has following advantages:1) It's convenient to sample and analyze on-line signal through implementing EMD method by hardware, especially in some situations requiring realtime processing and quasi-realtime processing;2) It's easy to show DSP's high-speed and high-efficiency as using its powerful signal processing ability to implement EMD method;3) Rapid data transmission and other high performance of PCI local bus can be fully used.According to the realizing procedure of EMD method and features of DSP and PCI, technologies of developing a signal acquisition/processing card and implementing EMD method is discussed. The paper has fulfill following jobs:1. Implementation of PCI interface of this card. Data is transmitted to system memory directly with PCI local bus, which solves the realtime transmission and storage of data and also provides convenience for signal realtime processing.2. Implementation of data acquisition with high speed and synchronization. The data is stored in on-chip RAM of DSP.3. EMD method is implemented by DSP. A simple mirror-extension method is taken to sovle the end extending issue in EMD method. And data in on-chip RAM is processed by the approach, and each IMF is transmitted to PC.4. The application on PC serves as the implementation of storage and display of IMF results.The paper provides some experiences for future research on EMD implementation by hardware.