Thesis - Instituto de Telecomunicações

80 CHAPTER 4. SIGNAL PROCESSING AND FEATURE EXTRACTIONto the first and second order signal derivative zeros, expressed in equation (4.26) - at evenlyspaced intervals. Also, we evaluate the ability of the proposed method to address situationsof overlapping and small amplitude events.Figure 4.6: EDA signal segment and corresponding detected events using the proposedmodel. The vertical dashed lines mark the t 0 instant of each detected event. The detectedevents are depicted aligned with 0. The bottom plot depicts the a scaled view of the detectedevents.Figure 4.6 illustrates the obtained results, showing 25 seconds of acquired EDA signal(continuous upper line); the SCR events, detected by the application of our proposed modeland method, are also presented at the bottom of the figure, immediately following the detectedonset times t o , indicated by vertical dashed lines. From this figure, it is apparent theability of the proposed method to correctly detect and extract overlapping events. Detailedobservation of the first two marked events, amplified in the bottom plot of the figure, showsthe ability to detect subtle, small amplitude events, superimposed in a decreasing zone ofa stronger SCR event. Significant events can be selected by applying some threshold over