3. The processing of raw EMG involves filtering, rectification and further filtering to obtain the processed signal as in Figure 1. Figure 1: (Top) Raw EMG signal and (bottom) Processed EMG signal. a. Identify the first filtering process and define the specifications of this filter. Explain the main purpose of this filter. [2 marks] b. Rectification is the process of changing all the bipolar values in EMG into all-positive values. Write the MATLAB code for this process. Assume y is the rectified signal, and EMGx is the first filtered signal. [2 marks] c. Explain the purpose of the following filter process after rectification. What is the range of window size in milliseconds for EMG? What will happen if the moving average window size is smaller than the stated range? [2 marks] d. The final process is to represent a single muscle contraction activity into a single parameter. Name the two method that can be used to achieve this. What is the difference between the two methods, in terms of its calculations? [4 marks]