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Page of 11 ZOOM OTHER PROBLEMS SAVE FOR FINAL EXAM 7. (8 pts) Individuals with c

ID: 2292763 • Letter: P

Question

Page of 11 ZOOM OTHER PROBLEMS SAVE FOR FINAL EXAM 7. (8 pts) Individuals with chronic spinal 8 Extension cord injury often exhibit multi-joint reflex E activity that is known as extensor spasm The figure on the right shows a time-3 series and power spectrum plot of ankle 50 torque measurements as the hip is articulated using a sinusoidal motion at 0.2 Hz (flexion and extension). (From Steldt and Schmit (2004) J Neurophys) o 20 2 10 0.5 20 40 Time (s) Frequency (Hz) a. Based on the plots above, indicate whether the data is periodic. Provide an explanation for your choice in each case b. Name two signal processing approaches that you could take to characterize the spectral characteristics of the signal over time

Explanation / Answer

A) Torque Vs Time graph is periodic between 20 to 40

Explanation :

In periodic signal "Signal repeats same pattern after equal interval of time", The time required to complete one cycle is called "Time Period" of the signal.

In given graph signal repeating itself between 20 to 40 .

(B)

If we look at the signal Torque Vs Time .. "Signal is partially periodic between 20 to 40" spectrum can be charactrize between 20 to 40 using "Fourier Series Expansion".

But overall signal is aperiodic : Fourier tranform will be an appropriate signal processing tool for spectrum analysis.

Signal extracted from limbs and body parts called EMG signal and having high degree of fluctation . There some effecient techniques to characterize spectrals characteristics are as follows

1. STFT (Short time Fourier Transform)

2.  Hilbert-Huang transformation

3. Wavelet transformation methods