Serious end effect will be produced while the upper and lower envelope is constructed in the process of EMD. Similar extrema extension method was proposed to overcome the problem. Abscissa difference of adjacent extrema at both ends of data was considered as the shape characteristic, then the shape characteristic and average of extrema were used to extend signal. Both trend of extrema variation near boundary and rest of extrema were considered in similar extrema extension, while only the extrema near boundary was used to extend signal in current
SHEN Lu ZHOU Xiaojun ZHANG Zhigang ZHANG Wenbin.
A BOUNDARY-EXTENSION METHOD IN HILBERT-HUANG TRANSFORM[J]. Journal of Vibration and Shock, 2009, 28(8): 168-171