Choi-Williams time-frequency analysis of forearm flexors Mechanomyogram acquired from a laser diode sensor based probe

Abstract

The aim of this paper is to show how time-frequency plane can be used to directly read the frequency contents of forearm flexors muscles vibrations actually called MMG signals (Mechanomyogram). The MMG signals under scope are acquired from a laser diode sensor based probe connected to precise interface acquisition cards and the acquired signals are put into the memory of a PC for further analysis. The time-frequency technique used is the Choi-Williams energy distribution which belongs to the well reputed Cohen's class and satisfies many very useful properties especially in its 3D version. With this technique a good compromise between time and frequency resolution can be found. The 3D spectrograms displayed from the data acquired from few normal subjects and patients with specific muscle disorders are compared. This analysis method revealed an efficient localization of the MMG most significant frequencies.